Pressure Dependence Of Electrical Resistivity Research Articles

Experimental investigation of the effect of nickel on the electrical resistivity of Fe-Ni and Fe-Ni-S alloys under pressure

AbstractElectrical resistivity experiments were conducted on three alloys in the iron-rich side of the Fe-Ni(-S) system (Fe-5 wt% Ni, Fe-10 wt% Ni, Fe-10 wt% Ni-5 wt% S) at 4.5 and 8 GPa and up to 1900 K using the multi-anvil apparatus and the 4-electrode technique. For all samples, increasing temperature increases resistivity. At a specified temperature, Fe-Ni(-S) alloys are more resistive than Fe by a factor of about 3. Fe-Ni alloys containing 5 and 10 wt% Ni present comparable electrical resistivity values. The resistivity of Fe-Ni(-S) alloys is comparable to the one of Fe = 5 wt% S at 4.5 GPa and is about three times higher than the resistivity of Fe = 5 wt% S at 8 GPa, due to a different pressure dependence of electrical resistivity between Fe-Ni and Fe-S alloys. Based on these electrical results and experimentally determined thermal conductivity values from the literature, lower and upper bounds of thermal conductivity were calculated. For all Ni-bearing alloys, thermal conductivity estimates range between ~12 and 20 W/(m⋅K) over the considered pressure and temperature ranges. Adiabatic heat fluxes were computed for both Ganymede's core and the Lunar core, and heat flux values suggest a significant dependence to both core composition and the adiabatic temperature. Comparison with previous thermochemical models of the cores of Ganymede and the Moon suggests that some studies may have overestimated the thermal conductivity and hence, the heat flux along the adiabat in these planetary cores.

Electric and Galvanomagnetic Properties of Cd3As2–20 mol % MnAs Composite under High Pressure

The pressure dependences of electrical resistance, Hall coefficient, charge carrier mobilities, and magnetoresistance of the Cd3As2–20 mol % MnAs composite are investigated at pressures up to 9 GPa. The pressure dependences of all the listed properties exhibit features related to phase transitions. The presence of pressure-induced negative magnetoresistance is registered.

Влияние высокого давления на электрические и гальваномагнитные свойства композита Cd-=SUB=-3-=/SUB=-As-=SUB=-2-=/SUB=--20mol.% MnAs

Abstract The pressure dependences of electrical resistance, Hall coefficient, charge carrier mobilities, and magnetoresistance of the Cd_3As_2–20 mol % MnAs composite are investigated at pressures up to 9 GPa. The pressure dependences of all the listed properties exhibit features related to phase transitions. The presence of pressure-induced negative magnetoresistance is registered.

Pressure dependence of resistivity and magnetic properties in a Mn1.9Cr0.1Sb alloy

We report magnetic-field and hydrostatic pressure dependent electrical resistivity and magnetic properties of a Mn1.9Cr0.1Sb alloy. Upon cooling, the magnetization of Mn1.9Cr0.1Sb exhibits a first-order ferrimagnetic to antiferromagnetic transition at the exchange inversion temperature, TS = 261 K under a 0.1 T magnetic field. Our experimental results show that TS decreases with increasing magnetic field but increase with increasing hydrostatic pressure. The pressure induced transition is accompanied by a large positive baro-resistance of 30.5% for a hydrostatic pressure change of 0.69 GPa. These results show that the lattice parameters as well as the bond distance between Mn-Mn atoms play a crucial role in the magnetic and electronic transport properties of Mn1.9Cr0.1Sb. This sample also exhibits a large inverse magnetocaloric effect with a magnetic entropy change of ΔSm = +6.75 J/kg.K and negative magnetoresistance (44.5%) for a field change of 5 T at TS in ambient pressure which may be useful for magnetic cooling and spintronics applications.

Investigation of pressure dependence of electrical resistivity based on mean-field approximation in Gd-element

Eigenvalue calculations were performed on the mechanism of electro-magnetic coupling in order to evaluate the effective exchange Jij in the induced negative exchange potential in Gd by which the emergence of the Kondo-like character around TC by low pressure is possible. Since the two subsystems, i.e. “local spin exchange” and “conduction band”, are competently separated in Gd, the response of both systems to the pressure is investigated in the range of θP/TC. First, the mechanism of mean field approximation through the conduction electron can be manifested by ρ(T) and second, the challenging effect could be characterized by local dynamic distortion that is appeared to change appreciably at the onset of magnetic phase transition. The calculations were based on the molecular field approximation in order to consider the effect of sign and strength of exchange interaction for different reciprocal lattice directions and for various correlation lengths RC=2KFRij. Validity of this model was evaluated by means of electrical resistivity measurement for this element, in which the mechanism of coupling between Gd and the conduction electron is more evident in the generation of a minimum character in the electrical resistivity, which shifts toward higher values by a low static pressure. The experimental and theoretical results were in good agreement with the available previous data.

Studies of electrical resistivity of highly oriented pyrolytic graphite under high pressures at room temperature

The pressure dependence of electrical resistivity of highly oriented pyrolytic graphite is investigated at room temperature. The time needed to stabilize a sample’s resistance at constant pressure ranges from one hour to several days. The influence of the thickness of a sample and a current passed through it on the magnitude and pronouncedness of characteristic features in the pressure dependence of graphite resistance is found.

Electrical resistance of single-crystal magnetite (Fe3O4) under quasi-hydrostatic pressures up to 100 GPa

The pressure dependence of electrical resistance of single-crystal magnetite (Fe3O4) was measured under quasi-hydrostatic conditions to 100 GPa using low-temperature, megabar diamond-anvil cell techniques in order to gain insight into the anomalous behavior of this material that has been reported over the years in different high-pressure experiments. The measurements under nearly hydrostatic pressure conditions allowed us to detect the clear Verwey transition and the high-pressure structural phase. The appearance of a metallic ground state after the suppression of the Verwey transition around 20 GPa and the concomitant enhancement of the electrical resistance caused by the structural transformation to the high-pressure phase form reentrant semiconducting-metallic-semiconducting behavior, although the appearance of the metallic phase is highly sensitive to stress conditions and details of the measurement technique.

Weak ferromagnetism in a noncentrosymmetric BiPd 4 K superconductor

We report the synthesis of noncentrosymmetric BiPd single crystal by the self-flux method. The BiPd single crystal is crystallized in monoclinic structure with the P21 space group. Detailed SEM (scanning electron microscopy) results show that the crystals are formed in a slab like morphology with homogeneous distribution of Bi and Pd. The magnetic susceptibility measurements confirmed that the BiPd compound is superconducting below 4 K. Further, BiPd exhibits weak ferromagnetism near the superconducting transition temperature in isothermal magnetization (MH) measurements. The temperature-dependent electrical resistivity also confirmed that the BiPd single crystal is superconducting at Tc = 4 K. Magnetotransport measurements showed that the estimated Hc2(0) value is around 7.0 kOe. We also obtained a sharp peak in heat capacity Cp(T) measurements below 4 K due to superconducting ordering. The normalized specific heat jump, ΔC/γTc, is 1.52, suggesting the BiPd to be an intermediate BCS coupled superconductor. The pressure-dependent electrical resistivity shows that the Tc decreases with increasing applied pressure and the obtained dTc/dP is −0.62 K Gpa−1. Summarily, detailed superconductivity characterization of noncentrosymmetric BiPd single crystal is performed and discussed briefly in the present article.

Ferromagnetic Kondo behavior inUAuBi2single crystals

We combine magnetization, pressure-dependent electrical resistivity, and heat capacity measurements to investigate the physical properties of the novel compound ${\mathrm{UAuBi}}_{2}$. Our single crystals, grown by the self-flux method, share the same tetragonal ${\mathrm{HfCuSi}}_{2}$-type structure as their Ce-based counterparts. ${\mathrm{UAuBi}}_{2}$ shows ferromagnetic ordering at ${T}_{c}=22.5$ K, in contrast with the antiferromagnetic transition found in ${\mathrm{CeAuBi}}_{2}$ $({T}_{N}=12\text{K})$ but closely related to ${\mathrm{UAuSb}}_{2}$ $({T}_{c}=31\text{K})$. Despite the differences, all compounds display an easy axis of magnetization along the $c$ axis and a large magnetocrystalline anisotropy. The heat capacity and pressure-dependent resistivity suggest that ${\mathrm{UAuBi}}_{2}$ exhibits moderately heavy-fermion behavior $(\ensuremath{\gamma}\ensuremath{\sim}100\phantom{\rule{0.28em}{0ex}}\mathrm{mJ}/\mathrm{mol}\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{K}}^{2})$ with strongly localized $5f$ electrons. An intricate competition between crystalline electric field (CEF) effects and two anisotropic exchange interactions $({J}_{\mathrm{RKKY}})$ persists in the $5f$ system, which leads to the striking difference between ground states. A systematic analysis of our macroscopic data using a mean-field model including anisotropic ${J}_{\mathrm{RKKY}}$ interactions and the tetragonal CEF Hamiltonian allows us to extract the CEF scheme and the values of ${J}_{\mathrm{RKKY}}$. Our results suggest a general trend in this family of compounds and shed light on the similarities and differences between $4f$ and $5f$ members.

Revisit of Pressure-Induced Phase Transition in PbSe: Crystal Structure, and Thermoelastic and Electrical Properties

Lead selenide, PbSe, an important lead chalcogenide semiconductor, has been investigated using in-situ high-pressure/high-temperature synchrotron X-ray diffraction and electrical resistivity measurements. For the first time, high-quality X-ray diffraction data were collected for the intermediate orthorhombic PbSe. Combined with ab initio calculations, we find a Cmcm, InI-type symmetry for the intermediate phase, which is structurally more favorable than the anti-GeS-type Pnma. At room temperature, the onset of the cubic-orthorhombic transition was observed at ∼3.5 GPa with a ∼3.4% volume reduction. At an elevated temperature of 1000 K, the reversed orthorhombic-to-cubic transition was observed at 6.12 GPa, indicating a positive Clapeyron slope for the phase boundary. Interestingly, phase-transition induced elastic softening in PbSe was also observed, which can be mainly attributed to the loosely bonded trigonal prisms along the b-axis in the Cmcm structure. In a comparison with the cubic phase, orthorhombic PbSe exhibits a large negative pressure dependence of electrical resistivity. In addition, thermoelastic properties of orthorhombic PbSe have been derived from isothermal compression data, such as the temperature derivative of bulk modulus and thermally induced pressure.

3d magnetism in ThCo2Sn2 single crystals

Intense efforts have been made in order to synthesize new tetragonal ternary intermetallic compounds with low-temperature ground states on the border of magnetism. Here we report the synthesis of ThCo2Sn2 single crystals, which crystallize in the tetragonal CaBe2Ge2-type structure, using the flux technique. Further investigation of the physical properties by magnetic susceptibility and pressure-dependent electrical resistivity measurements confirm the presence of antiferromagnetic ordering associated with the Co ions, but with a higher ordering temperature of TN = 78 K when compared to TN = 65 K of the polycrystalline counterpart. Our results show that both Cu-substitution and applied pressure up to 22 kbar are not able to induce superconductivity in this system. Nevertheless, our analyses point out to a putative quantum critical point at higher pressures.

Magnetic properties of nearly stoichiometric CeAuBi2 heavy fermion compound

Motivated by the interesting magnetic anisotropy found in the heavy fermion family CeTX2 (T = transition metal and X = pnictogen), here, we study the novel parent compound CeAu1−xBi2−y by combining magnetization, pressure dependent electrical resistivity, and heat-capacity measurements. The magnetic properties of our nearly stoichiometric single crystal sample of CeAu1−xBi2−y (x = 0.92 and y = 1.6) revealed an antiferromagnetic ordering at TN = 12 K with an easy axis along the c-direction. The field dependent magnetization data at low temperatures reveal the existence of a spin-flop transition when the field is applied along the c-axis (Hc ∼ 7.5 T and T = 5 K). The heat capacity and pressure dependent resistivity data suggest that CeAu0.92Bi1.6 exhibits a weak heavy fermion behavior with strongly localized Ce3+ 4f electrons. Furthermore, the systematic analysis using a mean field model including anisotropic nearest-neighbors interactions and the tetragonal crystalline electric field (CEF) Hamiltonian allows us to extract a CEF scheme and two different values for the anisotropic JRKKY exchange parameters between the Ce3+ ions in this compound. Thus, we discuss a scenario, considering both the anisotropic magnetic interactions and the tetragonal CEF effects, in the CeAu1−xBi2−y compounds, and we compare our results with the isostructural compound CeCuBi2.

Physical properties and magnetic structure of the intermetallicCeCuBi2compound

In this work, we combined magnetization, pressure dependent electrical resistivity, heat-capacity, 63Cu Nuclear Magnetic Resonance (NMR) and X-ray resonant magnetic scattering experiments to investigate the physical properties of the intermetallic CeCuBi2 compound. Our single crystals show an antiferromagnetic ordering at TN ~ 16 K and the magnetic properties indicate that this compound is an Ising antiferromagnet. In particular, the low temperature magnetization data revealed a spin-flop transition at T = 5 K when magnetic fields about 5.5 T are applied along the c-axis. Moreover, the X-ray magnetic diffraction data below TN revealed a commensurate antiferromagnetic structure with propagation wavevector (0 0 1/2) with the Ce^3+ moments oriented along the c-axis. Furthermore, our heat capacity, pressure dependent resistivity and temperature dependent 63Cu NMR data suggest that CeCuBi2 exhibits a weak heavy fermion behavior with strongly localized Ce^3+ 4f electrons. We thus discuss a scenario taking into account the anisotropic magnetic interaction between the Ce^3+ ions along with the tetragonal crystalline electric field effects in CeCuBi2.

Electronic topological transition and semiconductor-to-metal conversion of Bi2Te3 under high pressure

Accurate high pressure in situ Hall-effect and temperature dependent electrical resistivity measurements have been carried out on Bi2Te3, a topological insulator. The pressure dependent electrical resistivity, Hall coefficient, carrier concentration, and mobility show the abnormal inflection points at 8, 12, and 17.8 GPa, indicating that the pressure-induced structural phase transitions of Bi2Te3 can result in a series of changes in the carrier transport behavior. In addition, the Hall coefficient shows a significant discontinuous change at 4 GPa, which is caused by the electronic topological transition. A sign inversion of Hall coefficient from positive to negative is found around 8 GPa. Furthermore, the temperature dependent electrical resistivity shows that the sample undergoes a semiconductor-to-metal conversion around 9.2 GPa, indicating that the insulating gap of Bi2Te3 becomes closed at this pressure. As the metallization occurs in the sample, the topological property of Bi2Te3 disappears.

Scaling relation found in anomalous electrical transport and superconductivity of heavy fermion superconductor URu2Si2

The pressure dependent electrical resistivity of URu2Si2 has been studied at high pressure across the first order phase boundary of Px where the ground state switches under pressure from “hidden order” (HO) to large moment antiferromagnetic (LAFM) states. We have measured an ultra-clean single crystal whose quality is the highest among those used in previous studies. We have previously analyzed the resistivity data with the generalized power law ρ = ρ0 + AnTn. It was found that the electric transport property deviates from Fermi liquid theory in the HO phase but obeys the theory well above Px. In this paper, we re-analyze the data using the polynomial in T expression ρ = ρ0 + α1T + α2T2. The analysis finds the relation α1/α2 α Tsc in the HO phase. While the pressure dependence of α2 is very weak, α1 is roughly proportional to Tsc. This suggests a strong correlation between the anomalous quasiparticle scattering and the superconductivity and that both have a common origin. The present study clarifies a universality of the HO phase inherent in strongly correlated electron superconductors near quantum criticality.

Electrical Resistivity of Assembled Transparent Inorganic Oxide Nanoparticle Thin Layers: Influence of Silica, Insulating Impurities, and Surfactant Layer Thickness

The electrical properties of transparent, conductive layers prepared from nanoparticle dispersions of doped oxides are highly sensitive to impurities. Production of cost-effective thin conducting films for consumer electronics often employs wet processing such as spin and/or dip coating of surfactant-stabilized nanoparticle dispersions. This inherently results in entrainment of organic and inorganic impurities into the conducting layer leading to largely varying electrical conductivity. Therefore, this study provides a systematic investigation on the effect of insulating surfactants, small organic molecules and silica in terms of pressure dependent electrical resistivity as a result of different core/shell structures (layer thickness). Application of high temperature flame synthesis gives access to antimony-doped tin oxide (ATO) nanoparticles with high purity. This well-defined starting material was then subjected to representative film preparation processes using organic additives. In addition ATO nanoparticles were prepared with a homogeneous inorganic silica layer (silica layer thickness from 0.7 to 2 nm). Testing both organic and inorganic shell materials for the electronic transport through the nanoparticle composite allowed a systematic study on the influence of surface adsorbates (e.g., organic, insulating materials on the conducting nanoparticle's surface) in comparison to well-known insulators such as silica. Insulating impurities or shells revealed a dominant influence of a tunneling effect on the overall layer resistance. Mechanical relaxation phenomena were found for 2 nm insulating shells for both large polymer surfactants and (inorganic) SiO(2) shells.

Strong correlation between anomalous quasiparticle scattering and unconventional superconductivity in the hidden-order phase of URu2Si2

The pressure dependent electrical resistivity of URu${}_{2}$Si${}_{2}$ has been studied at high pressure across the first order phase boundary of ${P}_{x}$ where the ground state switches under pressure from ``hidden order'' (HO) to large moment antiferromagnetic (LAFM) states. The electrical transport in URu${}_{2}$Si${}_{2}$ at low temperatures shows a strong sample dependence. We have measured an ultraclean single crystal whose quality is the highest among those used in previous studies. The generalized power law $\ensuremath{\rho}\phantom{\rule{0.16em}{0ex}}=\phantom{\rule{0.16em}{0ex}}{\ensuremath{\rho}}_{0}+\phantom{\rule{0.16em}{0ex}}{A}_{n}T{}^{n}$ analysis finds that the electric transport property deviates from Fermi liquid theory in the HO phase but obeys the theory well above ${P}_{x}$. The analysis using the polynomial in $T$ expression $\ensuremath{\rho}\phantom{\rule{0.16em}{0ex}}=\phantom{\rule{0.16em}{0ex}}{\ensuremath{\rho}}_{0}+\phantom{\rule{0.16em}{0ex}}{\ensuremath{\alpha}}_{1}T+\phantom{\rule{0.16em}{0ex}}{\ensuremath{\alpha}}_{2}T{}^{2}$ reveals the relation ${\ensuremath{\alpha}}_{1}/{\ensuremath{\alpha}}_{2}$ $\ensuremath{\propto}$ ${T}_{\text{sc}}$ in the HO phase. While the pressure dependence of ${\ensuremath{\alpha}}_{2}$ is very weak, ${\ensuremath{\alpha}}_{1}$ is roughly proportional to ${T}_{\text{sc}}$. This suggests a strong correlation between the anomalous quasiparticle scattering and the superconductivity and that both have a common origin. The present study clarifies a universality of the HO phase inherent in strongly correlated electron superconductors near quantum criticality.

Pressure-induced metallization of BaMn2As2

Temperature- and pressure-dependent electrical resistivity [($\ensuremath{\rho}T$,$P$)] studies have been performed on BaMn${}_{2}$As${}_{2}$ single crystal in the 4.2--300 K range up to 8.2 GPa in order to investigate the evolution of its ground state properties. \ensuremath{\rho}($T$) data show negative coefficients of resistivity up to a pressure of 3.2 GPa. At a pressure of \ensuremath{\sim}4.5 GPa an insulator-to-metal transition is seen to occur at \ensuremath{\sim}36 K, as indicated by a change in the temperature coefficient of the \ensuremath{\rho}($T$). However, at a pressure of \ensuremath{\sim}5.8 GPa the sample is metallic in the entire temperature range. X-ray diffraction studies performed as a function of pressure, at room temperature, also show an anomaly in the pressure versus volume curve around $P$ \ensuremath{\approx} 5 GPa without a change in crystal structure, indicative of an electronic transition in support of the resistivity results. In addition to metallization, a clear precipitous drop in \ensuremath{\rho}($T$) is seen at \ensuremath{\sim}17 K for $P$ \ensuremath{\ge} 5.8 GPa.

High pressure studies on RuIn3 single crystal

Temperature- and pressure-dependent electrical resistivity studies have been carried out onRuIn3 single crystal in the 4–300 K range at various pressures between 0 and 5 GPa.While intrinsic semiconducting behaviour is inferred at higher temperatures above275 K, the low temperature resistivity is primarily dictated by impurity effects. Aninsulator to metal transition is observed in the low temperature regime around ∼ 1.2 GPa pressure. Band structure calculations show a monotonic decrease of energy gap from avalue of 0.222 eV at 0 GPa to 0.167 eV at 8 GPa with increasing pressure, consistent with theexperimental findings.

Study on phase transition of SrTiO3 by in situ impedance measurement under high pressure

The pressure dependence of electrical resistance of perovskite SrTiO 3 has been studied by in situ impedance measurement in diamond anvil cell up to 31GPa at room temperature. Two discontinuous changes in resistance were observed at about 9.8 and 21 GPa, which are coincident with the pressure-induced phase transitions from cubic phase to tetragonal phase and then to orthorhombic phase, respectively. High-pressure angle dispersive X-ray diffraction experiments on SrTiO 3 powders have also been performed up to 35 GPa. It was found that a structure phase transition from cubic to tetragonal phase begins to take place at about 6.49 GPa but clear indication for a further transition to an orthorhombic phase at higher pressure up to 35 GPa is hardly seen in our X-ray diffraction data.