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2008-04-26
Origin of resistivity minima at low temperature in ferromagnetic metallic manganites
The resistivity and magnetoresistance measurements were carried out on thin film of La0.7Ca0.3MnO3 to investigate the possible origin of low temperature resistivity minimum observed in these samples. We observed large hysteresis in the magnetoresistance at low temperature; 5K and the sample current I has large effect on resistivity minima temperature. The observation of hysteresis at low temperatures suggests the presence of inhomogeneity at low temperatures. These in-homogeneities consist of regions of different resistive phases. It appears that the high resistive phase prevents the tunneling of charge carriers between two low resistive regions and thus giving rise to the resistivity minimum in these samples.
0804.4247v1
2015-08-05
The universal influence of contact resistance on the efficiency of a thermoelectric generator
The influence of electrical and thermal contact resistance on the efficiency of a segmented thermoelectric generator is investigated. We consider 12 different segmented $p$-legs and 12 different segmented $n$-legs, using 8 different $p$-type and 8 different $n$-type thermoelectric materials. For all systems a universal influence of both the electrical and thermal contact resistance is observed on the leg's efficiency, when the systems are analyzed in terms of the contribution of the contact resistance to the total resistance of the leg. The results are compared with the analytical model of Min and Rowe (1992). In order for the efficiency not to decrease more than 20%, the contact electrical resistance should be less than 30% of the total leg resistance for zero thermal contact resistance, while the thermal contact resistance should be less than 20% for zero electrical contact resistance. The universal behavior also allowed the maximum tolerable contact resistance for a segmented system to be found, i.e. the resistance at which a leg of only the high temperature thermoelectric material has the same efficiency as the segmented leg with a contact resistance at the interface. If e.g. segmentation increases the efficiency by 30% then an electrical contact resistance of 30% or a thermal contact resistance of 20% can be tolerated.
1508.01153v1
2018-02-10
Electroforming Free Controlled Bipolar Resistive Switching in Al/CoFe2O4/FTO device with Self-Compliance Effect
Controlled bipolar resistive switching (BRS) has been observed in nanostructured CoFe2O4 films using Al(aluminum)/CoFe2O4/FTO(fluorine-doped tin oxide) device. The fabricated device shows electroforming-free uniform BRS with two clearly distinguished and stable resistance states without any application of compliance current (CC), with a resistance ratio of high resistance state (HRS) and low resistance state (LRS) > 102. Small switching voltage (< 1 volt) and lower current in both the resistance states confirms the fabrication of low power consumption device. In the LRS, the conduction mechanism was found to be of Ohmic in nature, while the high-resistance state (HRS/OFF state) was governed by space charge-limited conduction mechanism, which indicates the presence of an interfacial layer with imperfect microstructure near the top Al/CFO interface. The device shows nonvolatile behavior with good endurance properties, acceptable resistance ratio, uniform resistive switching due to stable, less random filament formation/rupture and a control over the resistive switching properties by choosing different stop voltages, which makes the device suitable for its application in future nonvolatile resistive random access memory (ReRAM).
1802.03643v1
2021-08-20
Understanding grain boundary electrical resistivity in Cu: the effect of boundary structure
Grain boundaries (GBs) in metals usually increase electrical resistivity due to their distinct atomic arrangement compared to the grain interior. While the GB structure has a crucial influence on the electrical properties, its relationship with resistivity is poorly understood. Here, we perform a systematic study on the resistivity and structure relationship in Cu tilt GBs, employing high resolution in-situ electrical measurements coupled with atomic structure analysis of the GBs. Excess volume and energies of selected GBs are calculated using molecular dynamics simulations. We find a consistent relation between the coincidence site lattice (CSL) type of the GB and its resistivity. The most resistive GBs are high range of low-angle GBs (misorientation 14 to 18 degrees) with twice the resistivity of high angle tilt GBs, due to the high dislocation density and corresponding strain fields. Regarding the atomistic structure, GB resistivity approximately correlates with the GB excess volume. Moreover, we show that GB curvature increases resistivity by about 80%, while phase variations and defects within the same CSL type do not considerably change it.
2108.09148v1
2003-12-07
Temperature-dependent contact resistances in high-quality polymer field-effect transistors
Contact resistances between organic semiconductors and metals can dominate the transport properties of electronic devices incorporating such materials. We report measurements of the parasitic contact resistance and the true channel resistance in bottom contact poly(3-hexylthiophene) (P3HT) field-effect transistors with channel lengths from 400 nm up to 40 $\mu$m, from room temperature down to 77 K. For fixed gate voltage, the ratio of contact to channel resistance decreases with decreasing temperature. We compare this result with a recent model for metal-organic semiconductor contacts. Mobilities corrected for this contact resistance can approach 1 cm$^{2}$/Vs at room temperature and high gate voltages.
0312183v1
2024-02-26
A novel method for determining the resistivity of compressed superconducting materials
The resistivity of a superconductor in its normal state plays a critical role in determining its superconducting ground state. However, measuring the resistivity of a material under high pressure has long presented a significant technical challenge due to pressure-induced changes in the crystallographic directions, especially for samples with anisotropic layered structures like high-Tc superconductors and other intriguing quantum materials. Here, we are the first to propose a novel and effective method for determining high-pressure resistivity, which relies on the ambient-pressure resistivity, initial sample sizes, lattice parameters, high-pressure resistance, and lattice parameters measured from the same sample. Its validity has been confirmed through our investigations of pressurized copper-oxide superconductors, which demonstrates that this method provides new possibilities for researchers conducting high-pressure studies related to resistivity of these materials.
2402.16257v1
2021-09-14
Internal reverse-biased p-n junctions: a possible origin of the high resistance in phase change superlattice
Phase change superlattice is one of the emerging material technologies for ultralow-power phase change memories. However, the resistance switching mechanism of phase change superlattice is still hotly debated. Early electrical measurements and recent materials characterizations have suggested that the Kooi phase is very likely to be the as-fabricated low-resistance state. Due to the difficulty in in-situ characterization at atomic resolution, the structure of the electrically switched superlattice in its high-resistance state is still unknown and mainly investigated by theoretical modellings. So far, there has been no simple model that can unify experimental results obtained from device-level electrical measurements and atomic-level materials characterizations. In this work, we carry out atomistic transport modellings of the phase change superlattice device and propose a simple mechanism accounting for its high resistance. The modeled high-resistance state is based on the interfacial phase changed superlattice that has previously been mistaken for the low-resistance state. This work advances the understanding of phase change superlattice for emerging memory applications.
2109.06376v1
2018-04-23
Magnetic field-induced resistivity upturn and exceptional magneto-resistance in Weyl semimetal TaSb2
We study magneto-transport properties in single crystals of TaSb_2, which is a recently discovered topological semimetal. In the presence of magnetic field, the electrical resistivity shows onset of insulating behaviour followed by plateau at low temperature. Such resistivity plateau is generally assigned to topological surface states. TaSb2 exhibits extremely high magneto-resistance with non-saturating field dependence. We find that aspects of extremely large magneto resistance and resistivity plateau are well accounted by classical Kohler scaling. Unambiguous evidence for anomalous Chiral transport is provided with observation of negative longitudinal magneto-resistance. Shubnikov-de Haas oscillations reveal two dominating frequencies, 201 T and 455 T. These aspects categorize TaSb2 as a Type-II Weyl semimetal. At low temperature, the field dependence of Hall resistivity shows non-linear behaviour that indicates the presence of two types of charge carriers in consonance with reported electronic band structure. Analysis of Hall resistivity imply very high electron mobilities.
1804.08434v1
2023-07-12
Machine learning accelerated discovery of corrosion-resistant high-entropy alloys
Corrosion has a wide impact on society, causing catastrophic damage to structurally engineered components. An emerging class of corrosion-resistant materials are high-entropy alloys. However, high-entropy alloys live in high-dimensional composition and configuration space, making materials designs via experimental trial-and-error or brute-force ab initio calculations almost impossible. Here we develop a physics-informed machine-learning framework to identify corrosion-resistant high-entropy alloys. Three metrics are used to evaluate the corrosion resistance, including single-phase formability, surface energy and Pilling-Bedworth ratios. We used random forest models to predict the single-phase formability, trained on an experimental dataset. Machine learning inter-atomic potentials were employed to calculate surface energies and Pilling-Bedworth ratios, which are trained on first-principles data fast sampled using embedded atom models. A combination of random forest models and high-fidelity machine learning potentials represents the first of its kind to relate chemical compositions to corrosion resistance of high-entropy alloys, paving the way for automatic design of materials with superior corrosion protection. This framework was demonstrated on AlCrFeCoNi high-entropy alloys and we identified composition regions with high corrosion resistance. Machine learning predicted lattice constants and surface energies are consistent with values by first-principles calculations. The predicted single-phase formability and corrosion-resistant compositions of AlCrFeCoNi agree well with experiments. This framework is general in its application and applicable to other materials, enabling high-throughput screening of material candidates and potentially reducing the turnaround time for integrated computational materials engineering.
2307.06384v3
2014-08-26
Enhancement in Quality Factor of SRF Niobium Cavities by Material Diffusion
An increase in the quality factor of superconducting radiofrequency cavities is achieved by minimizing the surface resistance during processing steps. The surface resistance is the sum of temperature independent residual resistance and temperature/material dependent Bardeen-Cooper-Schrieffer (BCS) resistance. High temperature heat treatment usually reduces the impurities concentration from the bulk niobium, lowering the residual resistance. The BCS part can be reduced by selectively doping non-magnetic impurities. The increase in quality factor, termed as Q-rise, was observed in cavities when titanium or nitrogen thermally diffused in the inner cavity surface.
1408.6245v1
2015-12-15
A Graphene-Carbon Nanotube Hybrid Material for Photovoltaic Applications
Large area graphene sheets grown by chemical vapor deposition can potentially be employed as a transparent electrode in photovoltaics if their sheet resistance can be significantly lowered, without any loss in transparency. Here, we report the fabrication of a graphene-conducting-carbon-nanotube (CCNT) hybrid material with a sheet resistance considerably lower than neat graphene, and with the requisite small reduction in transparency. Graphene is deposited on top of a a self-assembled CCNT monolayer which creates parallel conducting paths on the graphene surface. The hybrid thereby circumvents electron scattering due to defects in the graphene sheet, and reduces the sheet resistance by a factor of two. The resistance can be further reduced by chemically doping the hybrid. Moreover, the chemically doped hybrid is more stable than a standalone chemically doped graphene sheet, as the CCNT network enhances the dopant binding. In order to understand the results, we develop a 2D resistance network model in which we couple the CCNT layer to the graphene sheet and demonstrate the model accounts quantitatively for the resistance decrease. Our results show that a graphene-CCNT hybrid system has high potential for use as a transparent electrode with high transparency and low sheet resistance.
1512.04617v1
2022-06-11
Modeling of High and Low Resistant States in Single Defect Atomristors
Resistance-change random access memory (RRAM) devices are nanoscale metal-insulator-metal structures that can store information in their resistance states, namely the high resistance (HRS) and low resistance (LRS) states. They are a potential candidate for a universal memory as these non-volatile memory elements can offer fast-switching, long retention and switching cycles, and additionally, are also suitable for direct applications in neuromorphic computing. In this study, we first present a model to analyze different resistance states of RRAM devices or so-called "atomristors" that utilize novel 2D materials as the switching materials instead of insulators. The developed model is then used to study the electrical characteristics of a single defect monolayer MoS$_{2}$ memristor. The change in the device resistance between the HRS and LRS is associated to the change in the tunneling probability when the vacancy defects in the 2D material are substituted by the metal atoms from the electrodes. The distortion due to defects and substituted metal atom is captured in the 1D potential energy profile by averaging the effect along the transverse direction. This simplification enables us to model single defect memristors with a less extensive quantum transport model while taking into account the presence of defects.
2206.05504v1
2011-06-06
Efficient resistive memory effect on SrTiO3 by ionic-bombardment
SrTiO3 is known to exhibit resistive memory effect either with cation-doping or with high-temperature thermal reduction. Here, we add another scheme, ionic-bombardment, to the list of tools to create resistive memory effect on SrTiO3 (STO). In an Ar-bombarded STO crystal, two orders of resistance difference was observed between the high and low resistive states, which is an order of magnitude larger than those achieved by the conventional thermal reduction process. One of the advantages of this new scheme is that it can be easily combined with lithographic processes to create spatially-selective memory effect.
1106.1203v1
2006-02-21
Evidance for an Oxygen Diffusion Model for the Electric Pulse Induced Resistance Change Effect in Oxides
Electric pulse induced resistance (EPIR) switching hysteresis loops for Pr0.7Ca0.7MnO3 (PCMO) perovskite oxide films were found to exhibit an additional sharp "shuttle peak" around the negative pulse maximum for films deposited in an oxygen deficient ambient. The device resistance hysteresis loop consists of stable high resistance and low resistance states, and transition regions between them. The resistance relaxation of the "shuttle peak" and its temperature behavior as well as the resistance relaxation in the transition regions were studied, and indicate that the resistance switching relates to oxygen diffusion with activation energy about 0.4eV. An oxygen diffusion model with the oxygen ions (vacancies) as the active agent is proposed for the non-volatile resistance switching effect in PCMO.
0602507v2
2014-06-16
Degenerate Resistive Switching and Ultrahigh Density Storage in Resistive Memory
We show that, in tantalum oxide resistive memories, activation power provides a multi-level variable for information storage that can be set and read separately from the resistance. These two state variables (resistance and activation power) can be precisely controlled in two steps: (1) the possible activation power states are selected by partially reducing resistance, then (2) a subsequent partial increase in resistance specifies the resistance state and the final activation power state. We show that these states can be precisely written and read electrically, making this approach potentially amenable for ultra-high density memories. We provide a theoretical explanation for information storage and retrieval from activation power and experimentally demonstrate information storage in a third dimension related to the change in activation power with resistance.
1406.4033v1
2020-06-10
Positive versus negative resistance response to hydrogenation in palladium and its alloys
Resistive solid state sensors are widely used in multiple applications, including molecular and gas detection. Absorption or intercalation of the target species varies the lattice parameters and an effective thickness of thin films, which is usually neglected in analyzing their transport properties in general and the sensor response in particular. Here, we explore the case of palladium-based thin films absorbing hydrogen and demonstrate that expansion of thickness is an important mechanism determining the magnitude and the very polarity of the resistance response to hydrogenation in high resistivity films. The model of the resistance response that takes into account modifications of thickness was tested and confirmed in three Pd-based systems with variable resistivity: thin Pd films above and below the percolation threshold, thick Pd-SiO2 granular composite films with different content of silica, and Pd-rich CoPd alloys where resistivity depends on Co concentration. Superposition of the bulk resistivity increase due to hydride formation and decrease of film resistance due to thickness expansion provides a consistent explanation of the hydrogenation response in both continuous and discontinuous films with different structures and compositions.
2006.05801v1
2021-06-04
Noncured Graphene Thermal Interface Materials: Minimizing the Thermal Contact Resistance
We report on experimental investigation of thermal contact resistance of the noncuring graphene thermal interface materials with the surfaces characterized by different degree of roughness. It is found that the thermal contact resistance depends on the graphene loading non-monotonically, achieving its minimum at the loading fraction of ~15 wt.%. Increasing the surface roughness by ~1 micrometer results in approximately the factor of x2 increase in the thermal contact resistance for this graphene loading. The obtained dependences of the thermal conductivity, thermal contact resistance, and the total thermal resistance of the thermal interface material layer on the graphene loading and surface roughness indicate the need for optimization of the loading fraction for specific materials and roughness of the connecting surfaces. Our results are important for developing graphene technologies for thermal management of high-power-density electronics.
2106.02180v1
2002-10-24
Violation of Ioffe-Regel condition but saturation of resistivity of the high Tc cuprates
We demonstrate that the resistivity data of a number of high Tc cuprates, in particular La(2-x)SrxCuO4, are consistent with resistivity saturation, although the Ioffe-Regel condition is strongly violated. By using the f-sum rule together with calculations of the kinetic energy in the t-J model, we show that the saturation resistivity is unusually large. This is related to the strong reduction of the kinetic energy due to strong correlation effects. The fulfilment of the Ioffe-Regel condition for conventional transition metal compounds is found to be somewhat accidental.
0210543v1
2023-04-26
Theoretical Puncture Mechanics of Soft Compressible Solids
Accurate prediction of the force required to puncture a soft material is critical in many fields like medical technology, food processing, and manufacturing. However, such a prediction strongly depends on our understanding of the complex nonlinear behavior of the material subject to deep indentation and complex failure mechanisms. Only recently we developed theories capable of correlating puncture force with material properties and needle geometry. However, such models are based on simplifications that seldom limit their applicability to real cases. One common assumption is the incompressibility of the cut material, albeit no material is truly incompressible. In this paper we propose a simple model that accounts for linearly elastic compressibility, and its interplay with toughness, stiffness, and elastic strain-stiffening. Confirming previous theories and experiments, materials having high-toughness and low-modulus exhibit the highest puncture resistance at a given needle radius. Surprisingly, in these conditions, we observe that incompressible materials exhibit the lowest puncture resistance, where volumetric compressibility can create an additional (strain) energy barrier to puncture. Our model provides a valuable tool to assess the puncture resistance of soft compressible materials and suggests new design strategies for sharp needles and puncture-resistant materials.
2304.13838v1
2008-05-23
Non-hysteretic branches inside the hysteresis loop in VO2 films for focal plane array imaging bolometers
In the resistive phase transition in VO2, temperature excursions from points on the major hysteresis loop produce minor loops. We have found that for sufficiently small excursions these minor loops degenerate into single-valued, non-hysteretic branches (NHBs) having essentially the same or even higher temperature coefficient of resistance (TCR) as the semiconducting phase at room temperature. We explain this behavior and discuss the opportunities it presents for infrared imaging technology based on resistive microbolometers. It is possible to choose a NHB with 100 to 1000 times smaller resistivity than in a pure semiconducting phase, thus providing a microbolometer with low tunable resistivity and high TCR.
0805.3566v1
2021-05-26
Investigation of Forming Free Bipolar Resistive Switching Characteristics in Al/Mn3O4/FTO RRAM Device
Bipolar resistive switching (BRS) phenomenon has been demonstrated in Mn3O4 using Al (Aluminum)/Mn3O4/FTO (Fluorine doped Tin Oxide) Resistive Random Access Memory (RRAM) device. The fabricated RRAM device shows good retention, non volatile behavior and forming free BRS. The Current-Voltage (I-V) characteristics and the temperature dependence of the resistance (R-T) measurements were used to explore conduction mechanisms and the thermal activation energy (Ea). The resistance ratio of high resistance state (HRS) to low resistance state (LRS) is ~102. The fabricated RRAM device shows different conduction mechanisms in LRS and HRS state such as ohmic conduction and space charge limited conduction (SCLC). The rupture and formation of conducting filaments (CF) of oxygen vacancies take place by changing the polarity of external voltage, which may be responsible for resistive switching characteristics in the fabricated RRAM device. This fabricated RRAM device is suitable for application in future high density non-volatile memory (NVM) RRAM devices.
2105.12390v1
1998-08-18
Resistivity saturation revisited: results from a dynamical mean field theory
We use the dynamical mean field method to study the high-temperature resistivity of electrons strongly coupled to phonons. The results reproduce the qualtiative behavior of the temperature and disorder dependence of the resistivity of the 'A-15' materials, which is commonly described in terms of saturation, but imply that the resistivity does not saturate. Rather, a change in temperature dependence occurs when the scattering becomes strong enough to cause a breakdown of the Migdal approximation.
9808188v2
2018-07-13
A new type of RPC with very low resistive material
There are several working groups that are currently working on high rate RPC's using different materials such as Si-based Ceramics, Low-resistive Glass, low-resistive bakelite etc. A new type of single gap RPC has been fabricated using very low-resistive carbon-loaded PTFE material to compete with all these other groups and materials. In terms of bulk resistivity, this material is the lowest and should in principle be able to work at the highest rates, provided the material can withstand working bias and radiation. The efficiency and noise rate of the RPC are measured with cosmic rays. The detail method of fabrication and first experimental results are presented.
1807.04984v1
2013-04-20
Electric-Field-Induced Resistive Switching in a Family of Mott Insulators : towards Non-Volatile Mott-RRAM Memories
The fundamental building blocks of modern silicon-based microelectronics, such as double gate transistors in non-volatile Flash memories, are based on the control of electrical resistance by electrostatic charging. Flash memories could soon reach their miniaturization limits mostly because reliably keeping enough electrons in an always smaller cell size will become increasingly difficult . The control of electrical resistance at the nanometer scale therefore requires new concepts, and the ultimate resistance-change device is believed to exploit a purely electronic phase change such as the Mott insulator to insulator transition [2]. Here we show that application of short electric pulses allows to switch back and forth between an initial high-resistance insulating state ("0" state) and a low-resistance "metallic" state ("1" state) in the whole class of Mott Insulator compounds AM4X8 (A = Ga, Ge; M= V, Nb, Ta; X = S, Se). We found that electric fields as low as 2 kV/cm induce an electronic phase change in these compounds from a Mott insulating state to a metallic-like state. Our results suggest that this transition belongs to a new class of resistive switching and might be explained by recent theoretical works predicting that an insulator to metal transition can be achieved by a simple electric field in a Mott Insulator. This new type of resistive switching has potential to build up a new class of Resistive Random Access Memory (RRAM) with fast writing/erasing times (50 ns to 10 {\mu}s) and resistance ratios \Delta R/R of the order of 25% at room temperature.
1304.5607v1
2012-06-26
Measurement of electrical properties of electrode materials for the bakelite Resistive Plate Chambers
Single gap (gas gap 2 mm) bakelite Resistive Plate Chamber (RPC) modules of various sizes from 10 cm \times 10 cm to 1 m \times 1 m have been fabricated, characterized and optimized for efficiency and time resolution. Thin layers of different grades of silicone compound are applied to the inner electrode surfaces to make them smooth and also to reduce the surface resistivity. In the silicone coated RPCs an efficiency > 90% and time resolution \sim 2 ns (FWHM) have been obtained for both the streamer and the avalanche mode of operation. Before fabrication of detectors the electrical properties such as bulk resistivity and surface resistivity of the electrode materials are measured carefully. Effectiveness of different silicone coating in modifying the surface resistivity was evaluated by an instrument developed for monitoring the I-V curve of a high resistive surface. The results indicate definite correlation of the detector efficiency for the atmospheric muons and the RPC noise rates with the surface resistivity and its variation with the applied bias voltage. It was also found that the surface resistivity varies for different grades of silicone material applied as coating, and the results are found to be consistent with the detector efficiency and noise rate measurements done with these RPCs.
1206.5894v1
2015-09-21
Resistive Switching in Nanodevices
Passing current at given threshold voltages through a metal/insulator/metal sandwich structure device may change its resistive state. Such resistive switching is unique to nanoscale devices, but its underlying physical mechanism remains unknown. We show that the different resistive states are due to different spontaneously charged states, characterized by different `band bending' solutions of Poisson's equation. For an insulator with mainly donor type defects, the low-resistivity state is characterized by a negatively charged insulator due to convex band bending, and the high-resistivity state by a positively charged insulator due to concave band bending; vice versa for insulators with mainly acceptor type defects. These multiple solutions coexist only for nanoscale devices and for bias voltages limited by the switching threshold values, where the system charge spontaneously changes and the system switches to another resistive state. We outline the general principles how this functionality depends on material properties and defect abundance of the insulator `storage medium', and propose a new magnetic memristor device with increased storage capacity.
1509.06169v1
2018-06-30
Nanoscale compositional evolution in complex oxide based resistive memories
Functional oxides based resistive memories are recognized as potential candidate for the next-generation high density data storage and neuromorphic applications. Fundamental understanding of the compositional changes in the functional oxides is required to tune the resistive switching characteristics for enhanced memory performance. Herein, we present the micro/nano-structural and compositional changes induced in a resistive oxide memory during resistive switching. Oxygen deficient amorphous chromium doped strontium titanate (Cr:$a$-SrTiO$_{3-x}$) based resistance change memories are fabricated in a Ti/Cr:$a$-SrTiO$_{3-x}$ heterostructure and subjected to different biasing conditions to set memory states. Transmission electron microscope based cross-sectional analyses of the memory devices in different memory states shows that the micro/nano-structural changes in amorphous complex oxide and associated redox processes define the resistive switching behavior. These experimental results provide insights and supporting material for Ref. [1].
1807.00185v1
2018-06-04
Atomistic Study of the Electronic Contact Resistivity Between the Half-Heusler Alloys (HfCoSb, HfZrCoSb, HfZrNiSn) and the Metal Ag
Half-Heusler(HH) alloys have shown promising thermoelectric properties in the medium and high temperature range. To harness these material properties for thermoelectric applications, it is important to realize electrical contacts with low electrical contact resistivity. However, little is known about the detailed structural and electronic properties of such contacts, and the expected values of contact resistivity. Here, we employ atomistic ab initio calculations to study electrical contacts in a subclass of HH alloys consisting of the compounds HfCoSb, HfZrCoSb, and HfZrNiSn. By using Ag as a prototypical metal, we show that the termination of the HH material critically determines the presence or absence of strong deformations at the interface. Our study includes contacts to doped materials, and the results indicate that the p-type materials generally form ohmic contacts while the n-type materials have a small Schottky barrier. We calculate the temperature dependence of the contact resistivity in the low to medium temperature range and provide quantitative values that set lower limits for these systems.
1806.01375v1
2009-01-28
Carbon Based Resistive Memory
We propose carbon as new resistive memory material for non-volatile memories and compare three allotropes of carbon, namely carbon nanotubes, graphene-like conductive carbon and insulating carbon for their possible application as resistance-change material in high density non-volatile memories. Repetitive high-speed switching and the potential for multi-level programming have been successfully demonstrated.
0901.4439v1
2016-01-31
Josephson-like Colossal Resistive Switching in Nanocrystalline Y-Ba-Cu-O at Room Temperature
In this paper, we present data for two nanocrystalline YBa2Cu3O7-x (YBCO) samples which both exhibit Josephson-like Colossal Resistive Switching (JCRS) in voltage-current (V-I) traces from 4.2 K up to room temperature, in magnetic fields up to 8 T. We report Josephson-like hysteresis for both positive and negative current that has not been observed before in colossal resistive switching materials. Non-zero resistance was measured in transport measurements at all temperatures. At low temperatures (< 90 K), we also observed the usual properties for YBCO including weak superconducting and paramagnetic behavior, measured using ac susceptibility and magnetization measurements. The resistivity of these nanocrystalline samples is 3 orders of magnitude higher than standard polycrystalline materials at 300 K and the temperature dependence semiconductor-like. We cannot rule out the possibility that these materials contain a superconducting component responsible for the JCRS behavior at room temperature.
1602.00271v3
2013-08-28
First studies with the Resistive-Plate WELL gaseous multiplier
We present the results of first studies of the Resistive Plate WELL (RPWELL): a single-faced THGEM coupled to a copper anode via a resistive layer of high bulk resistivity. We explored various materials of different bulk resistivity (10^9 - 10^12 Ohm cm) and thickness (0.4 - 4 mm). Our most successful prototype, with a 0.6 mm resistive plate of ~10^9 Ohm cm, achieved gains of up to 10^5 with 8 keV x-ray in Ne/5%CH4; a minor 30% gain drop occurred with a rate increase from 10 to 10^4 Hz/mm^2. The detector displayed a full "discharge-free" operation--even when exposed to high primary ionization events. We present the RPWELL detector concept and compare its performance to that of other previously explored THGEM configurations--in terms of gain, its curves, dependence on rate, and the response to high ionization. The robust Resistive Plate WELL concept is a step forward in the Micro-Pattern Gas-Detector family, with numerous potential applications.
1308.6152v1
2021-02-07
Quantum Conductors Formation and Resistive Switching Memory Effects in Zirconia Nanotubes
The development prospects of memristive elements for non-volatile memory with use of the metal-dielectric-metal sandwich structures with a thin oxide layer are due to the possibility of reliable forming the sustained functional states with quantized resistance. In the paper we study the properties of fabricated memristors based on the non-stoichiometric $ZrO_2$ nanotubes in different resistive switching modes. Anodic oxidation of the $Zr$ foil has been used to synthesize a zirconia layer of $1.7$ $\mu$$m$ thickness, consisting of an ordered array of vertically oriented nanotubes with outer diameter of 75 nm. $Zr/ZrO_2/Au$ sandwich structures have been fabricated by mask magnetron deposition. The effects of resistive switching in the $Zr/ZrO_2/Au$ memristors in unipolar and bipolar modes have been investigated. The resistance ratios $\geq3\cdot10^4$ between high-resistance (HRS) and low-resistance (LRS) states have been evaluated. It has been founded the conductivity of LRS is quantized in a wide range with minimum value of $0.5G_0=38.74$ $\mu$$S$ due to the formation of quantum conductors based on oxygen vacancies ($V_O$). Resistive switching mechanisms of $Zr/ZrO_2/Au$ memristors with allowing for migration of $V_O$ in an applied electric field have been proposed. It has been shown that the ohmic type and space charge limited conductivities are realized in the LRS and HRS, correspondingly. We present the results which can be used for development of effective memristors based on functional $Zr/ZrO_2/Au$ nanolayered structure with multiple resistive states and high resistance ratio.
2102.03764v1
2004-07-16
Negative Differential Resistivity and Positive Temperature Coefficient of Resistivity effect in the diffusion limited current of ferroelectric thin film capacitors
We present a model for the leakage current in ferroelectric thin- film capacitors which explains two of the observed phenomena that have escaped satisfactory explanation, i.e. the occurrence of either a plateau or negative differential resistivity at low voltages, and the observation of a Positive Temperature Coefficient of Resistivity (PTCR) effect in certain samples in the high-voltage regime. The leakage current is modelled by considering a diffusion-limited current process, which in the high-voltage regime recovers the diffusion-limited Schottky relationship of Simmons already shown to be applicable in these systems.
0407428v1
2015-05-18
Nonpolar resistive memory switching with all four possible resistive switching modes in amorphous ternary rare earth LaHoO3 thin films
We studied the resistive memory switching in pulsed laser deposited amorphous LaHoO3 (LHO) thin films for non-volatile resistive random access memory (RRAM) applications. Nonpolar resistive switching (RS) was achieved in PtLHOPt memory cells with all four possible RS modes ( positive unipolar, positive bipolar, negative unipolar, and negative bipolar) having high RON and ROFF ratios (in the range of 104 to 105) and non-overlapping switching voltages (set voltage, VON 3.6 to 4.2 V and reset voltage, VOFF 1.3 to 1.6 V) with a small variation of about 5 to 8 percent. X ray photoelectron spectroscopic studies together with temperature dependent switching characteristics revealed the formation of metallic holmium (Ho) and oxygen vacancies (VO) constituted conductive nanofilaments (CNFs) in the low resistance state (LRS). Detailed analysis of current versus voltage characteristics further corroborated the formation of CNFs based on metal like (Ohmic) conduction in LRS. Simmons Schottky emission was found to be the dominant charge transport mechanism in the high resistance state.
1505.04690v1
2019-07-23
Electron transport in high-entropy alloys: Al$_{x}$CrFeCoNi as a case study
The high-entropy alloys Al$_{x}$CrFeCoNi exist over a broad range of Al concentrations ($0 < x < 2$). With increasing Al content their structure is changed from the fcc to bcc phase. We investigate the effect of such structural changes on transport properties including the residual resistivity and the anomalous Hall resistivity. We have performed a detailed comparison of the first-principles simulations with available experimental data. We show that the calculated residual resistivities for all studied alloy compositions are in a fair agreement with available experimental data as concerns both the resistivity values and concentration trends. We emphasize that a good agreement with experiment was obtained also for the anomalous Hall resistivity. We have completed study by estimation of the anisotropic magnetoresistance, spin-disorder resistivity, and Gilbert damping. The obtained results prove that the main scattering mechanism is due to the intrinsic chemical disorder whereas the effect of spin polarization on the residual resistivity is appreciably weaker.
1907.09731v1
2018-04-14
Investigating the Composite/Metal Interface and its Influence on the Electrical Resistance Measurement
The advantages introduced by carbon fiber reinforced polymer (CFRP) composites has made them an appropriate choice in many applications and an ideal replacement for conventional materials. The benefits using CFRP composites are due to their lightweight, high stiffness, as well as corrosion resistance. For this reason, there is a fast growing trend in using CFRP composites for aircraft and wind turbine structural applications. The replacement of the conventional aerospace-grade metal alloys (aluminum, titanium, magnesium, etc.) with CFRP composites results in new challenges. For example, an aircraft during flight is prone to be struck by lightning. To withstand the injection of such massive amount of energy, adequate electrical properties, mainly electrical conductivity, is required. In fact, electrical conductance (or its reciprocal, resistance) is a critical parameter representing any material change and it can be considered an index for health monitoring. In this paper, AS4/8552 carbon/epoxy laminated composites were injected with two types of electrical currents, impulse current and direct current. The change in measured electrical resistance was recorded. A significant resistance drop occurred after electrical current injections. Furthermore, four-point flexural tests were performed on these composites to correlate an electrical resistance change with a potential flexural property change. There was no clear trend between a resistance change and flexural strength/modulus change of the test coupons, regardless of current injection. However, it was observed that the injection of the current affects the contact resistance such that its resistance decreases.
1804.06246v1
2018-08-09
Underlying burning resistant mechanisms for titanium alloy
The "titanium fire" as produced during high pressure and friction is the major failure scenario for aero-engines. To alleviate this issue, Ti-V-Cr and Ti-Cu-Al series burn resistant titanium alloys have been developed. However, which burn resistant alloy exhibit better property with reasonable cost needs to be evaluated. This work unveils the burning mechanisms of these alloys and discusses whether burn resistance of Cr and V can be replaced by Cu, on which thorough exploration is lacking. Two representative burn resistant alloys are considered, including Ti14(Ti-13Cu-1Al-0.2Si) and Ti40(Ti-25V-15Cr-0.2Si)alloys. Compared with the commercial non-burn resistant titanium alloy, i.e., TC4(Ti-6Al-4V)alloy, it has been found that both Ti14 and Ti40 alloys form "protective" shields during the burning process. Specifically, for Ti14 alloy, a clear Cu-rich layer is formed at the interface between burning product zone and heat affected zone, which consumes oxygen by producing Cu-O compounds and impedes the reaction with Ti-matrix. This work has established a fundamental understanding of burning resistant mechanisms for titanium alloys. Importantly, it is found that Cu could endow titanium alloys with similar burn resistant capability as that of V or Cr, which opens a cost-effective avenue to design burn resistant titanium alloys.
1808.02976v1
2005-10-03
Buffer-Enhanced Electrical-Pulse-Induced-Resistive Memory Effect in Thin Film Perovskites
A multilayer perovskite thin film resistive memory device has been developed comprised of: a Pr0.7Ca0.3MnO3 (PCMO) perovskite oxide epitaxial layer on a YBCO bottom thin film electrode; a thin yttria stabilized zirconia (YSZ) buffer layer grown on the PCMO layer, and a gold thin film top electrode. The multi-layer thin film lattice structure has been characterized by XRD and TEM analyses showing a high quality heterostructure. I-AFM analysis indicated nano granular conductivity distributed uniformly throughout the PCMO film surface. With the addition of the YSZ buffer layer, the pulse voltage needed to switch the device is significantly reduced and the resistance-switching ratio is increased compared to a non-buffered resistance memory device, which is very important for the device fabrication. The magnetic field effect on the multilayer structure resistance at various temperatures shows CMR behavior for both high and low resistance states implying a bulk material component to the switch behavior.
0510060v1
2020-04-24
Solution-processed silver sulphide nanocrystal film for resistive switching memories
Resistive switching memories allow electrical control of the conductivity of a material, by inducing a high resistance (OFF) or a low resistance (ON) state, using electrochemical and ion transport processes. As alternative to high temperature and vacuum-based physical sulphurization methods of silver (Ag), here we propose, as resistive switching medium, a layer built from colloidal Ag$_{2-x}$S nanocrystals -compatible with solution-processed approaches. The effect of the electrode size (from macro- to micro-scale), composition (Ag, Ti and Pt) and geometry on the device performance together with the electrochemical mechanisms involved are evaluated. We achieved an optimized Ag/Ti bowtie proof-of-concept configuration by e-beam lithography, which fulfils the general requirements for ReRAM devices in terms of low power consumption and reliable $I_{ON}/I_{OFF}$ ratio. This configuration demonstrates reproducible switching between ON and OFF states with data endurance of at least 20 cycles; and an $I_{ON}/I_{OFF}$ ratio up to 10$^3$ at low power consumption (0.1V readout), which outperforms previous results in literature for devices with resistive layers fabricated from silver chalcogenide nanoparticles.
2004.11875v1
2005-12-22
Measurement of Local Reactive and Resistive Photoresponse of a Superconducting Microwave Device
We propose and demonstrate a spatial partition method for the high-frequency photo-response of superconducting devices correlated with inductive and resistive changes in microwave impedance. Using a laser scanning microscope, we show that resistive losses are mainly produced by local defects at microstrip edges and by intergrain weak links in the high-temperature superconducting material. These defects initiate nonlinear high-frequency response due to overcritical current densities and entry of vortices.
0512572v1
2002-10-28
Nanometer-Scale Metallic Grains Connected with Atomic-Scale Conductors
We describe a technique for connecting a nanometer-scale gold grain to leads by atomic-scale gold point contacts. These devices differ from previous metallic quantum dots in that the conducting channels are relatively well-transmitting. We investigate the dependence of the Coulomb blockade on contact resistance. The high-resistance devices display Coulomb blockade and the low-resistance devices display a zero-bias conductance dip, both in quantitative agreement with theory. We find that in the intermediate regime, where the sample resistance is close to $h/e^2$, the I-V curve displays a Coulomb staircase with symmetric contact capacitances.
0210620v1
2004-08-05
Influence of Grain size on the Electrical Properties of ${\rm Sb_2Te_3}$ Polycrystalline Films
Resistance of vacuum deposited ${\rm Sb_2Te_3}$ films of thickness between 100-500nm has been measured in vacuum. It is found that the resistance of the polycrystalline films strongly depends on the grain size and inter-granular voids. The charge carrier are shown to cross this high resistivity inter- granular void by ohmic conduction. The barrier height as well as temperature coefficient of resistance are also shown to depend on the grain size and inter- grain voids.
0408116v1
2008-05-03
Resistance Quenching in Graphene Interconnects
We investigated experimentally the high-temperature electrical resistance of graphene interconnects. The test structures were fabricated using the focused ion beam from the single and bi-layer graphene produced by mechanical exfoliation. It was found that as temperature increases from 300 to 500K the resistance of the single- and bi-layer graphene interconnects drops down by 30% and 70%, respectively. The quenching and temperature dependence of the resistance were explained by the thermal generation of the electron-hole pairs and acoustic phonon scattering. The obtained results are important for the proposed applications of graphene as interconnects in integrated circuits.
0805.0334v1
2008-05-12
Negative differential resistance and pulsed current induced multi-level resistivity switching in charge ordered and disordered manganites
We have investigated direct and pulsed current induced electroresistance in two manganites with different electronic and magnetic ground states: charge-orbital ordered 50 % Ca doped NdMnO3 and 50 % Mn doped LaNiO3. It has been shown that negative differential resistance observed at high current density in these compounds is related to Joule heating. However, bi-level and multi-level resistivity switching induced by variations in pulse width and pulse period at low current density can not be attributable to Joule heating alone. We discuss possible origins.
0805.1643v1
2012-07-13
Enhanced Resolution of Poly-(Methyl Methacrylate) Electron Resist by Thermal Processing
Granular nanostructure of electron beam resist had limited the ultimate resolution of electron beam lithography. We report a thermal process to achieve a uniform and homogeneous amorphous thin film of poly methyl methacrylate electron resist. This thermal process consists of a short time-high temperature backing process in addition to precisely optimized development process conditions. Using this novel process, we patterned arrays of holes in a metal film with diameter smaller than 5nm. In addition, line edge roughness and surface roughness of the resist reduced to 1nm and 100pm respectively.
1207.3183v1
2016-11-12
Anomalous resistivity upturn in epitaxial L21-Co2MnAl films
We report the controllable growth and the intriguing transport behavior of high-spin-polarization epitaxial L21-Co2MnAl films, which exhibit a low-temperature (T) resistivity upturn with pronounced T1/2 dependence, close relevance to structural disorder, and robust independence of magnetic fields. The resistivity upturn turns out to be qualitatively contradictory to weak localization, particle-particle channel electron-electron interaction (EEI), and orbital two-channel Kondo effect, leaving a three-dimensional particle-hole channel EEI the most likely physical source. Our result highlights a considerable tunability of the structural and electronic disorder of magnetic films by varying growth temperature, affording unprecedented insights into the spin polarization and the resistivity upturn.
1611.04013v2
2011-04-06
Temperature dependence of contact resistance of Au-Ti-Pd2Si-n+-Si ohmic contacts
We investigated temperature dependence of contact resistance of an Au-Ti-Pd2Si ohmic contact to heavily doped n+-Si. The contact resistance increases with temperature owing to conduction through the metal shunts. In this case, the limiting process is diffusion input of electrons to the metal shunts. The proposed mechanism of contact resistance formation seems to realize also in the case of wide-gap semiconductors with high concentration of surface states and dislocation density in the contact.
1104.1030v1
2021-04-25
Electrical resistivity in 2d Kondo lattice systems
I extend the calculations represented in \cite{konav} regarding the resistivity in Kondo lattice materials from $3d$ syatem to $2d$ systems. In the present work I consider a 2d system, and memory function is computed. However, results found in 2d case are different from 3d system . I find that in $2d$ in low temperature regime($ k_{B}T\ll \mu_d$) resistivity shows power law($\frac{1}{T}$) behaviour and in the high temeprature regime($ k_{B}T\gg\mu_d$) resistivity varies linearly with temperature. In $3d$ these behaviours are as $\frac{1}{T}$ and as $T^{\frac{3}{2}}$ respectively.
2104.12129v1
2008-01-22
Abnormal Resistance Switching Behaviors of NiO Thin Films: Possible Occurrence of Simultaneous Formation and Rupture of Conducting Channels
We report the detailed current-voltage (I-V) characteristics of resistance switching in NiO thin films. In unipolar resistance switching, it is commonly believed that conducting filaments will rupture when NiO changes from a low resistance to a high resistance state. However, we found that this resistance switching can sometimes show abnormal behavior during voltage- and current-driven I-V measurements. We used the random circuit breaker network model to explain how abnormal switching behaviors could occur. We found that this resistance change can occur via a series of avalanche processes, where conducting filaments could be formed as well as ruptured.
0801.3323v1
2009-08-12
Large 1/f noise of unipolar resistance switching and its percolating nature
We investigated the 1/f noise of Pt/NiO/Pt capacitors that show unipolar resistance switching. When they were switched from the low to high resistance states, the power spectral density of the voltage fluctuation was increased by approximately five orders of magnitude. At 100 K, the relative resistance fluctuation, SR/R2, in the low resistance state displayed a power law dependence on the resistance R with exponent w = 1.6. This behavior can be explained by percolation theory; however, at higher temperatures or near the switching voltage, SR/R2 becomes enhanced further. This large 1/f noise can be therefore an important problem in the development of resistance random access memory devices.
0908.1606v1
2017-04-11
Scalability of Voltage-Controlled Filamentary and Nanometallic Resistance Memories
Much effort has been devoted to device and materials engineering to realize nanoscale resistance random access memory (RRAM) for practical applications, but there still lacks a rational physical basis to be relied on to design scalable devices spanning many length scales. In particular, the critical switching criterion is not clear for RRAM devices in which resistance changes are limited to localized nanoscale filaments that experience concentrated heat, electric current and field. Here, we demonstrate voltage-controlled resistance switching for macro and nano devices in both filamentary RRAM and nanometallic RRAM, the latter switches uniformly and does not require forming. As a result, using a constant current density as the compliance, we have achieved area-scalability for the low resistance state of the filamentary RRAM, and for both the low and high resistance states of the nanometallic RRAM. This finding will help design area-scalable RRAM at the nanoscale.
1704.03415v1
2021-10-07
A Modern-day Alchemy: Double Glow Plasma Surface Metallurgy Technology
In the long history of science and technology development, one goal is to diffuse solid alloy elements into the surface of steel materials to form surface alloys with excellent physical and chemical properties. On the basis of plasma nitriding technology, double glow plasma surface metallurgy technology has answered this challenge. This technology, which seems to be a modern-day alchemy, can use any element in the periodic table of chemical elements, including solid metal elements and their combinations, to form many types of surface alloyed layers with high hardness, wear resistance, corrosion resistance and high temperature oxidation resistance on various metal materials. For examples, nickel base alloys, stainless steels and high speed steels are formed on the surfaces of ordinary carbon steels; and high hardness, wear resistance and high temperature oxidation resistance alloy are formed on the surface of titanium alloy.This article briefly introduces the formation and principle of double glow plasma surface metallurgy technology, and summarizes the experimental results and industry application. The significance and development prospect of this technology are discussed.
2110.03236v1
2019-09-15
Large Resistivity Reduction in Mixed-Valent CsAuBr$_3$ Under Pressure
We report on high-pressure $p \leq 45$ GPa resistivity measurements on the perovskite-related mixed-valent compound CsAuBr$_3$. The compounds high-pressure resistivity can be classified into three regions: For low pressures ($p < 10$ GPa) an insulator to metal transition is observed; between $p= 10$ GPa and 14 GPa the room temperature resistivity goes through a minimum and increases again; above $p = 14$ GPa a semiconducting state is observed. From this pressure up to the highest pressure of $p = 45$ GPa reached in this experiment, the room-temperature resistivity remains nearly constant. We find an extremely large resistivity reduction between ambient pressure and 10 GPa by more than 6 orders of magnitude. This decrease is among the largest reported changes in the resistivity for this narrow pressure regime. We show - by an analysis of the electronic band structure evolution of this material - that the large change in resistivity under pressure in not caused by a crossing of the bands at the Fermi level. We find that it instead stems from two bands that are pinned at the Fermi level and that are moving towards one another as a consequence of the mixed-valent to single-valent transition. This mechanism appears to be especially effective for the rapid buildup of the density of states at the Fermi level.
1909.06874v1
2023-02-25
Peculiarities of electron transport and resistive switching in point contacts on TiSe2, TiSeS and CuxTiSe2
TiSe2 has received much attention among the transition metals chalcogenides because of its thrilling physical properties concerning atypical resistivity behavior, emerging of charge density wave (CDW) state, induced superconductivity etc. Here, we report discovery of new feature of TiSe2, namely, observation of resistive switching in voltage biased point contacts (PCs) based on TiSe2 and its derivatives doped by S and Cu (TiSeS, CuxTiSe2). The switching is taking place between a low resistive mainly metallic-type state and a high resistive semiconducting-type state by applying bias voltage (usually below 0.5V), while reverse switching takes place by applying voltage of opposite polarity (usually below 0.5V). The difference in resistance between these two states can reach up to two orders of magnitude at the room temperature. The origin of the effect can be attributed to the variation of stoichiometry in PC core due to drift/displacement of Se/Ti vacancies under high electric field. Additionally, we demonstrated, that heating takes place in PC core, which can facilitate the electric field induced effect. At the same time, we did not found any evidence for CDW spectral features in our PC spectra for TiSe2. The observed resistive switching allows to propose TiSe2 and their derivatives as the promising materials, e.g., for non-volatile resistive random access memory (ReRAM) engineering.
2302.13085v1
2021-04-21
A First-Principles-Based Approach to The High-Throughput Screening of Corrosion-Resistant High Entropy Alloys
The design of corrosion-resistant high entropy alloys (CR-HEAs) is challenging due to the alloys' virtually astrological composition space. To facilitate this, efficient and reliable high-throughput exploratory approaches are needed. Toward this end, the current work reports a first-principles-based approach exploiting the correlations between work function, surface energy, and corrosion resistance (i.e., work function and surface energy are, by definitions, proportional and inversely proportional to an alloy's inherent corrosion resistance, respectively). Two Bayesian CALPHAD models (or databases) of work function and surface energy of FCC Co-Cr-Fe-Mn-Mo-Ni are assessed using discrete surface energies and work functions derived by density-functional theory (DFT) calculations. The models are then used to rank different Co-Cr-Fe-Mn-Mo-Ni alloy compositions. It is observed that the ranked alloys possess chemical traits similar to previously studied corrosion-resistance alloys, suggesting that the proposed approach can be used to reliably screen HEAs with potentially good inherent corrosion resistance.
2104.10590v1
2023-04-02
Percolation-induced resistivity drop in cold-pressed LuH2
The stoichiometric bulk LuH2 is a paramagnetic metal with high electrical conductivity comparable to simple metals. Here we show that the resistivity of cold-pressed (CP) LuH2 samples varies sensitively upon modifying the grain size or surface conditions via the grinding process, i.e., the CP pellets made of commercially purchased LuH2 powder remain metallic but exhibit thousands of times higher resistivity, while additional grinding of LuH2 powders in air further enhances the resistivity and even results in weakly localized behaviors. For these CP samples, interestingly, we can occasionally observe abrupt resistivity drops at high temperatures, which also show dependences on magnetic fields and electrical current. Measurements of variable-temperature XRD, magnetic susceptibility, and specific heat exclude the possibilities of structural, magnetic, and superconducting transitions for the observed resistivity drops. Instead, we tentatively attribute these above observations to the presence of insulating layers on the grain surface due to the modification of hydrogen stoichiometry or the pollution by oxygen/nitrogen. Percolation of the metallic grains through the insulating surfaces can explain the sudden drop in resistivity. The present results thus call for caution in asserting the resistivity drops as superconductivity and invalidate the background subtraction in analyzing the resistivity data.
2304.00558v1
2017-07-28
High-temperature quantum oscillations of the Hall resistance in bulk Bi$_2$Se$_3$
Helically spin-polarized Dirac fermions (HSDF) in protected topological surface states (TSS) are of high interest as a new state of quantum matter. In three-dimensional (3D) materials with TSS, electronic bulk states often mask the transport properties of HSDF. Recently, the high-field Hall resistance and low-field magnetoresistance indicate that the TSS may coexist with a layered two-dimensional electronic system (2DES). Here, we demonstrate quantum oscillations of the Hall resistance at temperatures up to 50 K in bulk Bi$_2$Se$_3$ with a high electron density $n$ of about $2\!\cdot\!10^{19}$ cm$^{-3}$. From the angular and temperature dependence of the Hall resistance and the Shubnikov-de Haas oscillations we identify 3D and 2D contributions to transport. Angular resolved photoemission spectroscopy proves the existence of TSS. We present a model for Bi$_2$Se$_3$ and suggest that the coexistence of TSS and 2D layered transport stabilizes the quantum oscillations of the Hall resistance.
1707.09181v1
2005-11-15
Unconventional Hall effect in oriented Ca$_3$Co$_4$O$_9$ thin films
Transport properties of the good thermoelectric misfit oxide Ca$_3$Co$_4$O$_9$ are examined. In-plane resistivity and Hall resistance measurements were made on epitaxial thin films which were grown on {\it c}-cut sapphire substrates using the pulsed laser deposition technique. Interpretation of the in-plane transport experiments relates the substrate-induced strain in the resulting film to single crystals under very high pressure ($\sim$ 5.5 GPa) consistent with a key role of strong electronic correlation. They are confirmed by the measured high temperature maxima in both resistivity and Hall resistance. While hole-like charge carriers are inferred from the Hall effect measurements over the whole investigated temperature range, the Hall resistance reveals a non monotonic behavior at low temperatures that could be interpreted with an anomalous contribution. The resulting unconventional temperature dependence of the Hall resistance seems thus to combine high temperature strongly correlated features above 340 K and anomalous Hall effect at low temperature, below 100 K.
0511374v1
2013-10-21
Micro Pixel Chamber with resistive electrodes for spark reduction
The Micro Pixel Chamber (mu-PIC) using resistive electrodes has been developed and tested. The surface cathodes are made from resistive material, by which the electrical field is reduced when large current is flowed. Two-dimensional readouts are achieved by anodes and pickup electrodes, on which signals are induced. High gas gain (> 60000) was measured using 55Fe (5.9 keV) source, and very intensive spark reduction was attained under fast neutron. The spark rate of resistive mu-PIC was only 10^-4 times less than that of conventional mu-PIC at the gain of 10^4. With these developments, a new MPGD with no floating structure is achieved, with enough properties of both high gain and good stability to detect MIP particles. In addition, mu-PIC can be operated with no HV applied on anodes by using resistive cathodes. Neither AC coupling capacitors nor HV pull up resisters are needed for any anode electrode. Signal readout is drastically simplified by that configuration.
1310.5550v1
2023-11-28
Quantifying the contribution of material and junction resistances in nano-networks
Networks of nanowires and nanosheets are important for many applications in printed electronics. However, the network conductivity and mobility are usually limited by the inter-particle junction resistance, a property that is challenging to minimise because it is difficult to measure. Here, we develop a simple model for conduction in networks of 1D or 2D nanomaterials, which allows us to extract junction and nanoparticle resistances from particle-size-dependent D.C. resistivity data of conducting and semiconducting materials. We find junction resistances in porous networks to scale with nanoparticle resistivity and vary from 5 Ohm for silver nanosheets to 25 GOhm for WS2 nanosheets. Moreover, our model allows junction and nanoparticle resistances to be extracted from A.C. impedance spectra of semiconducting networks. Impedance data links the high mobility (~7 cm2/Vs) of aligned networks of electrochemically exfoliated MoS2 nanosheets to low junction resistances of ~670 kOhm. Temperature-dependent impedance measurements allow us to quantitatively differentiate intra-nanosheet phonon-limited band-like transport from inter-nanosheet hopping for the first time.
2311.16740v1
2016-02-04
Low-Resistance 2D/2D Ohmic Contacts: A Universal Approach to High-Performance WSe2, MoS2, and MoSe2 Transistors
We report a new strategy for fabricating 2D/2D low-resistance ohmic contacts for a variety of transition metal dichalcogenides (TMDs) using van der Waals assembly of substitutionally doped TMDs as drain/source contacts and TMDs with no intentional doping as channel materials. We demonstrate that few-layer WSe2 field-effect transistors (FETs) with 2D/2D contacts exhibit low contact resistances of ~ 0.3 k ohm.um, high on/off ratios up to > 109, and high drive currents exceeding 320 uA um-1. These favorable characteristics are combined with a two-terminal field-effect hole mobility ~ 2x102 cm2 V-1 s-1 at room temperature, which increases to >2x103 cm2 V-1 s-1 at cryogenic temperatures. We observe a similar performance also in MoS2 and MoSe2 FETs with 2D/2D drain and source contacts. The 2D/2D low-resistance ohmic contacts presented here represent a new device paradigm that overcomes a significant bottleneck in the performance of TMDs and a wide variety of other 2D materials as the channel materials in post-silicon electronics.
1602.01790v1
2013-12-30
Deviations from Matthiessen rule and resistivity saturation effects in Gd and Fe
According to earlier first-principles calculations, the spin-disorder contribution to the resistivity of rare-earth metals in the paramagnetic state is strongly underestimated if Matthiessen's rule is assumed to hold. To understand this discrepancy, the resistivity of paramagnetic Fe and Gd is evaluated by taking into account both spin and phonon disorder. Calculations are performed using the supercell approach within the linear muffin-tin orbital method. Phonon disorder is modeled by introducing random displacements of the atomic nuclei, and the results are compared with the case of fictitious Anderson disorder. In both cases the resistivity shows a nonlinear dependence on the square of the disorder potential, which is interpreted as a resistivity saturation effect. This effect is much stronger in Gd than in Fe. The non-linearity makes the phonon and spin-disorder contributions to the resistivity non-additive, and the standard procedure of extracting the spin-disorder resistivity by extrapolation from high temperatures becomes ambiguous. An "apparent" spin-disorder resistivity obtained through such extrapolation is in much better agreement with experiment compared to the results obtained by considering only spin disorder. By analyzing the spectral function of the paramagnetic Gd in the presence of Anderson disorder, the resistivity saturation is explained by the collapse of a large area of the Fermi surface due to the disorder-induced mixing between the electronic and hole sheets.
1312.7802v1
2016-11-08
Controlling friction in a manganite surface by resistive switching
We report a significant change in friction of a $\rm La_{0.55}Ca_{0.45}MnO_3$ thin film measured as a function of the materials resistive state under ultrahigh vacuum conditions at room temperature by friction force microscopy. While friction is high in the insulating state, it clearly changes to lower values if the probed local region is switched to the conducting state via nanoscale resistance switching. Thus we demonstrate active control of friction without having to change the temperature or pressure. Upon switching back to an insulating state the friction increases again. The results are discussed in the framework of electronic friction effects and electrostatic interactions.
1611.02684v1
2019-10-05
Metamaterial insertions for resistive-wall beam-coupling impedance reduction
Resistive-wall impedance usually constitutes a significant percentage of the total beamcoupling impedance budget of an accelerator. Reduction techniques often entail high electrical-conductivity coatings. This paper investigates the use of negative-permittivity or negative-permeability materials for sensibly reducing or theoretically nearly cancelling resistive-wall impedance. The proposed approach is developed by means of an equivalent transmission-line model. The effectiveness of such materials is benchmarked for the negative permeability case with experimental measurements in two frequency bandwidths. This first-stage study opens the possibility of considering metamaterials for impedance mitigation.
1910.02246v1
2020-07-07
Resistivity saturation in an electron-doped cuprate
We report the observation of resistivity saturation in lightly doped ($x\sim 0.10)$ as-grown samples of the electron-doped cuprate La$_{2-x}$Ce$_x$CuO$_4$ (LCCO). The saturation occurs at resistivity values roughly consistent with the phenomenological Mott-Ioffe-Regel criterion once the low effective carrier density of these materials is included in the analysis. These results imply that, at least for light doping, the high-temperature metallic phase of these materials is not necessarily strange and may be understood as simply a low-density metal.
2007.03685v1
2015-06-24
Resonant tunneling in a quantum oxide superlattice
Resonant tunnelling is a quantum mechanical process that has long been attracting both scientific and technological attention owing to its intriguing underlying physics and unique applications for high-speed electronics. The materials system exhibiting resonant tunnelling, however, has been largely limited to the conventional semiconductors, partially due to their excellent crystalline quality. Here we show that a deliberately designed transition metal oxide superlattice exhibits a resonant tunnelling behaviour with a clear negative differential resistance. The tunnelling occurred through an atomically thin, lanthanum {\delta}-doped SrTiO3 layer, and the negative differential resistance was realized on top of the bipolar resistance switching typically observed for perovskite oxide junctions. This combined process resulted in an extremely large resistance ratio (~10^5) between the high and low-resistance states. The unprecedentedly large control found in atomically thin {\delta}-doped oxide superlattices can open a door to novel oxide-based high-frequency logic devices.
1506.07583v1
2021-08-26
An investigation of high entropy alloy conductivity using first-principles calculations
The Kubo-Greenwood equation, in combination with the first-principles Korringa-Kohn-Rostoker Coherent Potential Approximation (KKR-CPA) can be used to calculate the DC residual resistivity of random alloys at T = 0 K. We implemented this method in a multiple scattering theory based ab initio package, MuST, and applied it to the ab initio study of the residual resistivity of the high entropy alloy Al$_x$CoCrFeNi as a function of $x$. The calculated resistivities are compared with experimental data. We also predict the residual resistivity of refractory high entropy alloy MoNbTaV$_x$W. The calculated resistivity trends are also explained using theoretical arguments.
2108.11739v1
2024-01-27
Influence od the process parameters on the quality a efficiency of the resistance spot welding process of advanced high strength complex phase stells
The effects of electrical characteristics of an inverter combined with main welding parameters on the resistance spot weldability of advanced high strength steels AHSS CP1000 is investigated.
2401.15457v1
2016-02-22
The effect of Ta oxygen scavenger layer on HfO$_2$-based resistive switching behavior: thermodynamic stability, electronic structure, and low-bias transport
Reversible resistive switching between high-resistance and low-resistance states in metal-oxide-metal heterostructures makes them very interesting for applications in random access memories. While recent experimental work has shown that inserting a metallic "oxygen scavenger layer" between the positive electrode and oxide improves device performance, the fundamental understanding of how the scavenger layer modifies heterostructure properties is lacking. We use density functional theory to calculate thermodynamic properties and conductance of TiN/HfO$_2$/TiN heterostructures with and without Ta scavenger layer. First, we show that Ta insertion lowers the formation energy of low-resistance states. Second, while the Ta scavenger layer reduces the Schottky barrier height in the high-resistance state by modifying the interface charge at the oxide-electrode interface, the heterostructure maintains a high resistance ratio between high- and low-resistance states. Finally, we show that the low-bias conductance of device on-states becomes much less sensitive to the spatial distribution of oxygen removed from the HfO$_2$ in the presence of the Ta layer. By providing fundamental understanding of the observed improvements with scavenger layers, we open a path to engineer interfaces with oxygen scavenger layers to control and enhance device performance. In turn, this may enable the realization of a non-volatile low-power memory technology with concomitant reduction in energy consumption by consumer electronics and significant benefits to society.
1602.06793v1
2002-09-04
Electrical resistivity at large temperatures: Saturation and lack thereof
Many transition metal compounds show saturation of the resistivity at high temperatures, T, while the alkali-doped fullerenes and the high-Tc cuprates are usually considered to show no saturation. We present a model of transition metal compounds, showing saturation, and a model of alkali-doped fullerenes, showing no saturation. To analyze the results we use the f-sum rule, which leads to an approximate upper limit for the resistivity at large T. For some systems and at low T, the resistivity increases so rapidly that this upper limit is approached for experimental T. The resistivity then saturates. For a model of transition metal compounds with weakly interacting electrons, the upper limit corresponds to a mean free path consistent with the Ioffe-Regel condition. For a model of the high Tc cuprates with strongly interacting electrons, however, the upper limit is much larger than the Ioffe-Regel condition suggests. Since this limit is not exceeded by experimental data, the data are consistent with saturation also for the cuprates. After "saturation" the resistivity usually grows slowly. For the alkali-doped fullerenes, "saturation" can be considered to have happened already for T=0, due to orientational disorder. For these systems, however, the resistivity grows so rapidly after "saturation" that this concept is meaningless. This is due to the small band width and to the coupling to the level energies of the important phonons.
0209099v1
2023-12-26
Corrosion-resistant aluminum alloy design through machine learning combined with high-throughput calculations
Efficiently designing lightweight alloys with combined high corrosion resistance and mechanical properties remains an enduring topic in materials engineering. To this end, machine learning (ML) coupled ab-initio calculations is proposed within this study. Due to the inadequate accuracy of conventional stress-strain ML models caused by corrosion factors, a novel reinforcement self-learning ML algorithm (accuracy R2 >0.92) is developed. Then, a strategy that integrates ML models, calculated energetics and mechanical moduli is implemented to optimize the Al alloys. Next, this Computation Designed Corrosion-Resistant Al alloy is fabricated that verified the simulation. The performance (elongation reaches ~30%) is attributed to the H-captured Al-Sc-Cu phases (-1.44 eV H-1) and Cu-modified {\eta}/{\eta}' precipitation inside the grain boundaries (GBs). The developed Al-Mg-Zn-Cu interatomic potential (energy accuracy 6.50 meV atom-1) proves the cracking resistance of the GB region enhanced by Cu-modification. Conceptually, our strategy is of practical importance for designing new alloys exhibiting corrosion resistance and mechanical properties.
2312.15899v1
2001-03-01
Properties of Pt Schottky Type Contacts On High-Resistivity CdZnTe Detectors
In this paper we present studies of the I-V characteristics of CdZnTe detectors with Pt contacts fabricated from high-resistivity single crystals grown by the high-pressure Brigman process. We have analyzed the experimental I-V curves using a model that approximates the CZT detector as a system consisting of a reversed Schottky contact in series with the bulk resistance. Least square fits to the experimental data yield 0.78-0.79 eV for the Pt-CZT Schottky barrier height, and <20 V for the voltage required to deplete a 2 mm thick CZT detector. We demonstrate that at high bias the thermionic current over the Schottky barrier, the height of which is reduced due to an interfacial layer between the contact and CZT material, controls the leakage current of the detectors. In many cases the dark current is not determined by the resistivity of the bulk material, but rather the properties of the contacts; namely by the interfacial layer between the contact and CZT material.
0103005v1
2010-01-27
An anomalous butterfly-shaped magnetoresistance loop in an alloy, Tb4LuSi3
Magnetic-field (H) induced first-order magnetic transition and the assiciated electronic phase-separation phenomena are active topics of research in magnetism. Magnetoresistance (MR) is a key property to probe these phenomena and, in literature, a butterfly-shaped MR loop has been noted while cycling the field, with the envelope curve lying below the virgin curve in MR versus H plots of such materials. Here, we report an opposite behavior of MR loop for an alloy, Tb4LuSi3, at low temperatures (<<20 K) in the magnetically ordered state. Such an anomalous curve reveals unexpected domination of higher resistive high-field phase in electronic conduction, unlike in other materials where conducion is naturally by low-resistive high-field phase that follows first-order transition. The observed features reveal an unusual electronic phase separation, namely involving high-resistive high-field phase and low-resistive virgin phase.
1001.4942v1
2006-03-31
Clustering of vacancy defects in high-purity semi-insulating SiC
Positron lifetime spectroscopy was used to study native vacancy defects in semi-insulating silicon carbide. The material is shown to contain (i) vacancy clusters consisting of 4--5 missing atoms and (ii) Si vacancy related negatively charged defects. The total open volume bound to the clusters anticorrelates with the electrical resistivity both in as-grown and annealed material. Our results suggest that Si vacancy related complexes compensate electrically the as-grown material, but migrate to increase the size of the clusters during annealing, leading to loss of resistivity.
0603849v3
2024-01-26
New perspectives of Hall effects from first-principles calculations
The Hall effect has been a fascinating topic ever since its discovery, resulting in exploration of entire family of this intriguing phenomena. As the field of topology develops and novel materials emerge endlessly over the past few decades, researchers have been passionately debating the origins of various Hall effects. Differentiating between the ordinary Hall effect and extraordinary transport properties, like the anomalous Hall effect, can be quite challenging, especially in high-conductivity materials, including those with topological origins. In this study, we conduct a systematic and comprehensive analysis of Hall effects by combining the semiclassical Boltzmann transport theory with first principles calculations within the relaxation time approximation. We first highlight some striking similarities between the ordinary Hall effect and certain anomalous Hall effects, such as nonlinear dependency on magnetic field and potential sign reversal of the Hall resistivity. We then demonstrate that the Hall resistivity can be scaled with temperature and magnetic field as well, analogue to the Kohler's rule which scales the longitudinal resistivity under the relaxation time approximation. We then apply this Kohler's rule for Hall resistivity to two representative materials: ZrSiS and PtTe$_2$ with reasonable agreement with experimental measurement. Moreover, our methodology has been proven to be applicable to the planar Hall effects of bismuth, of perfect agreements with experimental observations. Our research on the scaling behavior of Hall resistivity addresses a significant gap in this field and provides a comprehensive framework for a deeper understanding of the Hall resistance family, and thus has potential to propel the field forward and spark further investigations into the fascinating world of Hall effects.
2401.15150v1
2012-04-12
Effect of crystallographic anisotropy on the resistance switching phenomenon in perovskites
Resistance switching effects in metal/perovskite contacts based on epitaxial c-axis oriented Y-Ba-Cu-O (YBCO) thin films with different crystallographic orientations have been studied. Three types of Ag/YBCO junctions with the contact restricted to (i) c-axis direction, (ii) ab-plane direction, and (iii) both were designed and fabricated, and their current-voltage characteristics have been measured. The type (i) junctions exhibited conventional bipolar resistance switching behavior, whereas in other two types the low-resistance state was unsteady and their resistance quickly relaxed to the initial high-resistance state. Physical mechanism based on the oxygen diffusion scenario, explaining such behavior, is discussed.
1204.2598v1
2013-04-07
Characterization and simulation of resistive-MPGDs with resistive strip and layer topologies
The use of resistive technologies to MPGD detectors is taking advantage for many new applications, including high rate and energetic particle flux scenarios. The recent use of these technologies in large area detectors makes necessary to understand and characterize the response of this type of detectors in order to optimize or constrain the parameters used in its production, material resistivity, strip width, or layer thickness. The values to be chosen will depend on the environmental conditions in which the detector will be placed, and the requirements in time resolution and gain, improving the detector performance for each given application. We present two different methods to calculate the propagation of charge diffusion through different resistive topologies; one is based on a FEM of solving the telegraph equation in our particular strip detector scheme, the other is based on a semi-analytical approach of charge diffusion and is used to determine the charge evolution in a resistive layer.
1304.2057v1
2014-07-31
Compact chromium oxide thin film resistors for use in nanoscale quantum circuits
We report on the electrical characterisation of a series of thin chromium oxide films, grown by dc sputtering, to evaluate their suitability for use as on-chip resistors in nanoelectronics. By increasing the level of oxygen doping, the room-temperature sheet resistance of the chromium oxide films was varied from 28$\Omega / \square$ to 32.6k$\Omega / \square$. The variation in resistance with cooling to 4.2K in liquid helium was investigated; the sheet resistance at 4.2K varied with composition from 65$\Omega / \square$ to above 20G$\Omega / \square$. All of the films measured displayed ohmic behaviour at all measured temperatures. For on-chip devices for quantum phase-slip measurements using niobium-silicon nanowires, interfaces between niobium-silicon and chromium oxide are required. By characterising the interface contact resistance, we found that a gold intermediate layer is favourable: the specfic contact resistivity of chromium-oxide-to-gold interfaces was 0.15 m$\Omega$cm$^2$, much lower than the value for direct chromium-oxide to niobium-silicon interfaces, 65m$\Omega$cm$^2$. We conclude that these chromium oxide films are suitable for use in nanoscale circuits as high-value resistors, with resistivity tunable by oxygen content.
1407.8467v1
2016-06-12
Interlayer Resistance of Misoriented MoS2
Interlayer misorientation in transition metal dichalcogenides alters the interlayer distance, the electronic band structure, and the vibrational modes, but, its effect on the interlayer resistance is not known. This work analyzes the coherent interlayer resistance of misoriented 2H-MoS2 for low energy electrons and holes as a function of the misorientation angle. The electronic interlayer resistance monotonically increases with the supercell lattice constant by several orders of magnitude similar to that of misoriented bilayer graphene. The large hole coupling gives low interlayer hole resistance that weakly depends on the misorientation angle. Interlayer rotation between an n-type region and a p-type region will suppress the electron current with little effect on the hole current. We estimate numerical bounds and explain the results in terms of the orbital composition of the bands at high symmetry points. Density functional theory calculations provide the interlayer coupling used in both a tunneling Hamiltonian and a non-equilibrium Green function calculation of the resistivity.
1606.03682v1
2017-11-30
Universal Scaling in Intrinsic Resistivity of Two-Dimensional Metal Borophene
Two-dimensional boron sheets (borophenes) have been successfully synthesized in experiments and are expected to exhibit intriguing transport properties such as the emergence of superconductivity and Dirac Fermions. However, quantitative understanding of intrinsic electrical transport of borophene has not been achieved. Here, we report a comprehensive first-principles study on electron-phonon driven intrinsic electrical resistivity (\r{ho}) of emerging borophene structures. We find that the resistivity is highly dependent on the atomic structures and electron density of borophene. Low-temperature resistivity of borophene \r{ho} exhibits a universal scaling behavior, which increases rapidly with temperature T (\r{ho}~T^4), while \r{ho} increases linearly for a large temperature window T > 100 K. It is observed that this universal behavior of intrinsic resistivity is well described by Bloch-Gr\"unesisen model. Different from graphene and conventional three-dimensional metals, the intrinsic resistivity of borophenes can be easily tuned by adjusting carrier densities while the Bloch-Gr\"unesisen temperature is nearly fixed at ~100 K. Our work suggests monolayer boron can serve as an intriguing platform for realizing high-tunable two-dimensional electronic devices.
1711.11186v1
2018-05-05
Tetrahedral amorphous carbon resistive memories with graphene-based electrodes
Resistive-switching memories are alternative to Si-based ones, which face scaling and high power consumption issues. Tetrahedral amorphous carbon (ta-C) shows reversible, non-volatile resistive switching. Here we report polarity independent ta-C resistive memory devices with graphene-based electrodes. Our devices show ON/OFF resistance ratios$\sim$4x$10^5$, ten times higher than with metal electrodes, with no increase in switching power, and low power density$\sim$14$\mu$W/$\mu$m$^2$. We attribute this to a suppressed tunneling current due to the low density of states of graphene near the Dirac point, consistent with the current-voltage characteristics derived from a quantum point contact model. Our devices also have multiple resistive states. This allows storing more than one bit per cell. This can be exploited in a range of signal processing/computing-type operations, such as implementing logic, providing synaptic and neuron-like mimics, and performing analogue signal processing in non-von-Neumann architectures
1805.02100v1
2017-03-10
Unipolar resistive switching in cobalt titanate thin films
We report giant resistive switching of an order of 104, long-time charge retention characteristics up to 104 s, non-overlapping SET and RESET voltages, ohmic in low resistance state (LRS) and space charge limited current (SCLC) mechanism in high resistance state (HRS) properties in polycrystalline perovskite Cobalt Titanate (CoTiO3 ~ CTO) thin films. Impedance spectroscopy study was carried out for both LRS and HRS states which illustrates that only bulk resistance changes after resistance switching, however, there is a small change (<10% which is in pF range) in the bulk capacitance value in both states. These results suggest that in LRS state current filaments break the capacitor in many small capacitors in a parallel configuration which in turn provides the same capacitance in both states even there was 90 degree changes in phase-angle and an order of change in the tangent loss.
1703.03662v1
2015-04-21
The question of intrinsic origin of the metal-insulator transition in i-AlPdRe quasicrystal
The icosahedral (i-) AlPdRe is the most resistive quasicrystalline alloy discovered so far. Resistivities ($\rho$) of $1\Omega cm$ at 4K and correlated resistance ratios ($RRR = \rho_{4K}/\rho_{300K}$) of more than 200 are observed in polycrystalline samples. These values are two orders of magnitude larger than for the isomorphous i-AlPdMn phase. We discuss here the controversial microscopic origin of the i-AlPdRe alloy electrical specificity. It has been proposed that the high resistivity values are due to extrinsic parameters, such as secondary phases or oxygen contamination. From comprehensive measurements and data from the literature including electronic transport correlated with micro structural and micro chemical analysis, we show that on the contrary there is mounting evidence in support of an origin intrinsic to the i-phase. Similarly to the other quasicrystalline alloys, the electrical resistivity of the i-AlPdRe samples depends critically on minute changes in the structural quality and chemical composition. The low resistivity in i-AlPdRe single-grains compared to polycrystaline samples can be explained by difference in chemical composition, heterogeneity and thermal treatment.
1504.05464v1
2023-04-08
Novel resistive charge-multipliers for dual-phase LAr-TPCs: towards stable operation at higher gains
Cryogenic versions of Resistive WELL (RWELL) and Resistive Plate WELL (RPWELL) detectors have been developed, aimed at stable avalanche multiplication of ionization electrons in dual-phase TPCs. In the RWELL, a thin resistive layer deposited on top of an insulator is inserted in between the electron multiplier (THGEM) and the readout anode; in the RPWELL, a resistive plate is directly coupled to the THGEM. Radiation-induced ionization electrons in the liquid are extracted into the gaseous phase. They drift into the THGEM's holes where they undergo charge multiplication. Embedding resistive materials into the multiplier proved to enhance operation stability due to the mitigation of electrical discharges - thus allowing operation at higher charge gain compared to standard THGEM (a.k.a. LEM) multipliers. We present the detector concepts and report on the main preliminary results.
2304.04044v4
2012-02-10
What Causes High Resistivity in CdTe
CdTe can be made semi-insulating by shallow donor doping. This is routinely done to obtain high resistivity in CdTe-based radiation detectors. However, it is widely believed that the high resistivity in CdTe is due to the Fermi level pinning by native deep donors. The model based on shallow donor compensation of native acceptors was dismissed based on the assumption that it is practically impossible to control the shallow donor doping level so precisely that the free carrier density can be brought below the desired value suitable for radiation detection applications. In this paper, we present our calculations on carrier statistics and energetics of shallow donors and native defects in CdTe. Our results show that the shallow donor can be used to reliably obtain high resistivity in CdTe. Since radiation detection applications require both high resistivity and good carrier transport, one should generally use shallow donors and shallow acceptors for carrier compensation and avoid deep centers that are effective carrier traps.
1202.2255v1
2003-05-17
Saturation of electrical resistivity
Resistivity saturation is observed in many metallic systems with a large resistivity, i.e., when the resistivity has reached a critical value, its further increase with temperature is substantially reduced. This typically happens when the apparent mean free path is comparable to the interatomic separations - the Ioffe-Regel condition. Recently, several exceptions to this rule have been found. Here, we review experimental results and early theories of resistivity saturation. We then describe more recent theoretical work, addressing cases both where the Ioffe-Regel condition is satisfied and where it is violated. In particular we show how the (semiclassical) Ioffe-Regel condition can be derived quantum-mechanically under certain assumptions about the system and why these assumptions are violated for high-Tc cuprates and alkali-doped fullerides.
0305412v1
2004-07-06
High pressure effects on the electrical resistivity behavior of the Kondo lattice, YbPd2Si2
We report the influence of external pressure (P= up to 8 GPa) on the temperature dependence of electrical resistivity of a Yb-based Kondo lattice, YbPd2Si2, which does not undergo magnetic ordering under ambient pressure condition. There are qualitative changes in the temperature dependence of electrical resistivity due to the application of external pressure. While the resistivity is found to vary quadratically below 15 K (down to 45 mK) characteristic of Fermi-liquids, a drop is observed below 0.5 K for P= 1 GPa. Since the resistance values do not attain zero, we are attempted to attribute this drop to magnetic ordering, rather than to superconductivity. The temperature at which this fall occurs goes through a peak as a function of P (8 K for2 GPa and about 5 K at higher pressures). mimicking Doniach's magnetic phase diagram. We conclude that this is one of the few Yb-based stoichiometric materials, in which one can travers from valence fluctuation to magnetic ordering by the application of external pressure.
0407125v1
2014-08-19
Effect of silicon resistivity on its porosification using metal induced chemical etching
A comparison of porous structures formed from silicon (Si) wafers with different resistivities has been reported here based on the morphological studies carried out using scanning electron microscope (SEM). The porous Si samples have been prepared using metal induced etching (MIE) technique from two different Si wafers having two different resistivities. It is observed that porous Si containing well aligned Si nanowires are formed from high resistivity (1-20 $\Omega$cm) Si wafer whereas interconnected pores or cheese like structures are formed from low resistivity (0.02 $\Omega$cm ) Si wafers after MIE. An explanation for the different porosification processes has also been proposed based on the initial doping level where number of dopants seems to be playing an important role on the etching process. Visible photoluminescence have been observed from all the porous samples possibly due to quantum confinement effect.
1408.4314v1
2020-09-07
Tuneable Magneto-Resistance by Severe Plastic Deformation
Bulk metallic samples were synthesized from different binary powder mixtures consisting of elemental Cu, Co, and Fe using severe plastic deformation. Small particles of the ferromagnetic phase originate in the conductive Cu phase, either by incomplete dissolution or by segregation phenomena during the deformation process. These small particles are known to give rise to granular giant magnetoresistance. Taking advantage of the simple production process, it is possible to perform a systematic study on the influence of processing parameters and material compositions on the magneto-resistance. Furthermore, it is feasible to tune the magnetoresistive behavior as a function of the specimens chemical composition. It was found that specimens of low ferromagnetic content show an almost isotropic drop in resistance in a magnetic field. With increasing ferromagnetic content, percolating ferromagnetic phases cause an anisotropy of the magnetoresistance. By changing the parameters of the high pressure torsion process, i.e., sample size, deformation temperature, and strain rate, it is possible to tailor the magnitude of giant magneto-resistance. A decrease in room temperature resistivity of approx. 3.5% was found for a bulk specimen containing an approximately equiatomic fraction of Co and Cu.
2009.02952v1
2017-11-22
High Efficiency Thin Film Superlattice Thermoelectric Cooler Modules Enabled by Low Resistivity Contacts
V-telluride superlattice thin films have shown promising performance for on-chip cooling devices. Recent experimental studies have indicated that device performance is limited by the metal/semiconductor electrical contacts. One challenge in realizing a low resistivity contacts is the absence of fundamental knowledge of the physical and chemical properties of interfaces between metal and V-telluride materials. Here we present a combination of experimental and theoretical efforts to understand, design and harness low resistivity contacts to V-tellurides. Ab initio calculations are used to explore the effects of interfacial structure and chemical compositions on the electrical contacts, and an ab initio based macroscopic model is employed to predict the fundamental limit of contact resistivity as a function of both carrier concentration and temperature. Under the guidance of theoretical studies, we develop an experimental approach to fabricate low resistivity metal contacts to V-telluride thin film superlattices, achieving a 100-fold reduction compared to previous work. Interfacial characterization and analysis using both scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy show the unusual interfacial morphology and the potential for further improvement in contact resistivity. Finally, we harness the improved contacts to realize an improved high-performance thermoelectric cooling module.
1711.08481v1
2000-02-17
Ion-Beam Induced Current in High-Resistance Materials
The peculiarities of electric current in high-resistance materials, such as semiconductors or semimetals, irradiated by ion beams are considered. It is shown that after ion--beam irradiation an unusual electric current may arise directed against the applied voltage. Such a negative current is a transient effect appearing at the initial stage of the process. The possibility of using this effect for studying the characteristics of irradiated materials is discussed. A new method for defining the mean projected range of ions is suggested.
0002264v1
2021-11-15
Resistive-nanoindentation on gold: Experiments and modeling of the electrical contact resistance
This paper reports the experimental, analytical, and numerical study of resistive-nanoindentation tests performed on gold samples (bulk and thin film). First, the relevant contributions to electrical contact resistance are discussed and analytically described. A brief comparison of tests performed on gold and on natively oxidized metals highlights the high reproducibility and the voltage-independence of experiments on gold(thanks to its oxide-free surface). Then, the evolution of contact resistance during nanoindentation is fully explained in terms of electronic transport regimes: starting from tunneling, electronic transport is then driven by ballistic conduction before ending with pure diffusive conduction. The corresponding analytical expressions, as well as their validity domains, are determined and compared with experimental data,showing excellent agreement. From there, focus is made on the diffusive regime. Resistive-nanoindentation outputs are fully described by analytical and finite-element modeling. The developed numerical framework allows a better understanding of the main parameters: it first assesses the technique capabilities (validity domains, sensitivity to tip defect, sensitivity to rheology, effect of an oxide layer, and so on), butit also validates the different assumptions made on current line distribution. Finally, it is shown that a simple calibration procedure allows a well-resolved monitoring of the contact area during resistive-nanoindentation performed on samples with complex rheologies (ductile thin film on an elastic substrate). Comparison to analytical and numerical approaches highlights the strength of resistive-nanoindentation for continuous area monitoring.
2111.15474v1
2023-08-09
Observation of abnormal resistance-temperature behavior along with diamagnetic transition in Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O-based composite
Recently, Sukbae Lee et al.reported that material Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O (LK-99) has a series of characteristics of room temperature superconductors, including diamagnetic transition, resistance jump, nearly zero-resistance, magnetic field-dependent IV characteristics and so on (10.6111/JKCGCT.2023.33.2.061, arXiv:2307.12008, arXiv:2307.12037). However, whether LK-99 is really a room temperature superconductor is still controversial. On the one hand, some people think that the relatively weak diamagnetism of LK-99 reported by Sukbae Lee et al. is not the Meissner effect. On the other hand, there are doubts about the authenticity of its zero-resistance test results. Global replication studies have shown that LK-99 does have a large diamagnetic (arXiv:2308.01516), and also found a zero-resistance behavior at a low temperature of 110 $^\circ$K (arXiv:2308.01192). However, up to now, there is still no direct reproducible evidence to support Sukbae Lee et al.'s conclusion that LK-99 is a room temperature superconductor. Here, a distinct resistance jump was observed at about 387 $^\circ$K under ambient pressure in our experiment for unclear reason including possible impurity's contribution. The overall resistance of the test LK-99 sample still shows semiconductivity, and the resistance cannot really drop to zero. Our findings indicate that to identify the true potential of LK-99, high quality crystals without impurity are very important.
2308.05001v1
1995-12-14
Vortex structure and resistive transitions in high-Tc superconductors
The nature of the resistive transition for a current applied parallel to the magnetic field in high-Tc materials is investigated by numerical simulation on the three dimensional Josephson junction array model. It is shown by using finite size scaling that for samples with disorder the critical temperature Tp for the c axis resistivity corresponds to a percolation phase transition of vortex lines perpendicularly to the applied field. The value of Tp is higher than the critical temperature for j perpendicular to H, but decreases with the thickness of the sample and with anisotropy. We predict that critical behavior around Tp should reflect in experimentally accessible quantities, as the I-V curves.
9512003v1
2010-06-26
Stabilizing the forming process in unipolar resistance switching using an improved compliance current limiter
The high reset current IR in unipolar resistance switching now poses major obstacles to practical applications in memory devices. In particular, the first IR-value after the forming process is so high that the capacitors sometimes do not exhibit reliable unipolar resistance switching. We found that the compliance current Icomp is a critical parameter for reducing IR-values. We therefore introduced an improved, simple, easy to use Icomp-limiter that stabilizes the forming process by drastically decreasing current overflow, in order to precisely control the Icomp- and subsequent IR-values.
1006.5132v1
2011-07-06
Hysteretic magnetic pinning and reversible resistance switching in High-Tc superconductor/ferromagnet multilayers
We study a high-TC superconducting (YBa2Cu3O7-d) / ferromagnetic (Co/Pt multilayer) hybrid which exhibits resistance switching driven by the magnetic history: depending on the direction of the external field, a pronounced decrease or increase of the mixed-state resistance is observed as magnetization reversal occurs within the Co/Pt multilayer. We demonstrate that stray magnetic fields cause these effects via i) creation of vortices/antivortices and ii) magnetostatic pinning of vortices that are induced by the external field.
1107.1122v1
2017-05-11
The role of contact resistance in graphene field-effect devices
The extremely high carrier mobility and the unique band structure, make graphene very useful for field-effect transistor applications. According to several works, the primary limitation to graphene based transistor performance is not related to the material quality, but to extrinsic factors that affect the electronic transport properties. One of the most important parasitic element is the contact resistance appearing between graphene and the metal electrodes functioning as the source and the drain. Ohmic contacts to graphene, with low contact resistances, are necessary for injection and extraction of majority charge carriers to prevent transistor parameter fluctuations caused by variations of the contact resistance. The International Technology Roadmap for Semiconductors, toward integration and down-scaling of graphene electronic devices, identifies as a challenge the development of a CMOS compatible process that enables reproducible formation of low contact resistance. However, the contact resistance is still not well understood despite it is a crucial barrier towards further improvements. In this paper, we review the experimental and theoretical activity that in the last decade has been focusing on the reduction of the contact resistance in graphene transistors. We will summarize the specific properties of graphene-metal contacts with particular attention to the nature of metals, impact of fabrication process, Fermi level pinning, interface modifications induced through surface processes, charge transport mechanism, and edge contact formation.
1705.04025v1
2022-09-13
Unconventional Resistivity Scaling in Topological Semimetal CoSi
Nontrivial band topologies in semimetals lead to robust surface states that can contribute dominantly to the total conduction. This may result in reduced resistivity with decreasing feature size contrary to conventional metals, which may highly impact the semiconductor industry. Here we study the resistivity scaling of a representative topological semimetal CoSi using realistic band structures and Green's function methods. We show that there exists a critical thickness d_c dividing different scaling trends. Above d_c, when the defect density is low such that surface conduction dominates, resistivity reduces with decreasing thickness; when the defect density is high such that bulk conduction dominates, resistivity increases in as conventional metals. Below d_c, the persistent remnants of the surface states give rise to decreasing resistivity down to the ultrathin limit, unlike in topological insulators. The observed CoSi scaling can apply to broad classes of topological semimetals, providing guidelines for materials screening and engineering. Our study shows that topological semimetals bear the potential of overcoming the resistivity scaling challenges in back-end-of-line interconnect applications.
2209.06135v1
2019-10-31
Tackling Challenges in Seebeck Coefficient Measurement of Ultra-High Resistance Samples with an AC Technique
Seebeck coefficient is a widely-studied semiconductor property. Conventional Seebeck coefficient measurements are based on DC voltage measurement. Normally this is performed on samples with low resistances below a few Mohm level. Meanwhile, certain semiconductors are highly intrinsic and resistive, many examples can be found in optical and photovoltaic materials. The hybrid halide perovskites that have gained extensive attention recently are a good example. Few credible studies exist on the Seebeck coefficient of, CH3NH3PbI3, for example. We report here an AC technique based Seebeck coefficient measurement, which makes high quality voltage measurement on samples with resistances up to 100Gohm. This is achieved through a specifically designed setup to enhance sample isolation and reduce meter loading. As a demonstration, we performed Seebeck coefficient measurement of a CH3NH3PbI3 thin film at dark and found S = +550 microV/K. Such property of this material has not been successfully studied before.
1910.14205v1
2021-04-03
Resistive switching of tetraindolyl derivative in ultrathin films: A potential candidate for non-volatile memory applications
Bipolar resistive switching using organic molecule is very promising for memory application owing to their advantages like simple device structure, low manufacturing cost, their stability and flexibility etc. Herein we report Langmuir-Blodgett and spin-coated film based bipolar resistive switching devices using organic material indole derivative. Pressure - area per molecule isotherm, Brewster Angle Microscopy, Atomic Force Microscopy and Scanning Electron Microscopy were used to have an idea about organization and morphology of the organic material onto thin film. Based on device structure and measurement protocol it is observed that the device made up of 1 shows non-volatile Resistive Random Access Memory behaviour with very high memory window, data sustainability and repeatability.Oxidation-reduction process as well as electric field driven conduction are the key behind such switching behaviour.Due to very good data retention, repeatability, stability and high device yield the switching device designed using compound 1may be a potential candidate for memory applications.
2104.01298v1