The temperature dependence of the electrical resistivity of granular metals

A simple percolation model of the hopping conduction in granular metals is proposed. The separation between the grains, in this model, is a random variable uncorrelated with the activation energy, the latter being dominated by the intragrain level splitting. The model is capable of reproducing the resistivity exp $\text{(}\text{T}{}_0\text{T}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ law over a wide temperature range, in spite of the narrow range of the grain diameters, explaining the recent observations of Choi et al.     

The temperature dependence of the electrical resistivity of gold films

An analysis is presented of resistivity data on thin gold films with a view to characterizing any surface-caused quadratic temperature dependence (T²) to the resistivity. No evidence is found for a T² term varying in magnitude according to the inverse sample thickness. This is in accord with other studies on gold foils and disagrees with a recent suggestion that surface scattering causes a T² contribution to the resistivity of the noble metals.     

The pressure- and temperature dependence of the electrical resistivity of some amorphous Fe-B alloys

We report measurements of the electrical resistivity of the amorphous alloys Fe₄₀Ni₄₀P₁₄B₆ (Metglas 2826). Fe₃₂Ni₃₆Cr₁₄P₁₂B₆ (Metglas 2826A) Fe₈₀B₂₀ (Metglas 2605) and Fe₇₅B₂₅ as a function of pressure and temperature. The pressure is varied between 0 and 12 GPa, the temperature between 1.2 and 380 K. At low temperatures the pressure dependence yields additional information on the scattering mechanism.     

Temperature dependence of the electrical resistivity and the anisotropic magnetoresistance (AMR) of electrodeposited Ni-Co alloys

The electrical resistivity and the anisotropic magnetoresistance (AMR) was investigated for Ni-Co alloys at and below room temperature. The Ni-Co alloy layers having a thickness of about 2 μm were prepared by electrodeposition on Si wafers with evaporated Cr and Cu underlayers. The alloy composition was varied in the whole concentration range by varying the ratio of Ni-sulfate and Co-sulfate in the electrolyte. The Ni-Co alloy deposits were investigated first in the as-deposited state on the substrates and then, by mechanically stripping them from the substrates, as self-supporting layers both without and after annealing. According to an X-ray diffraction study, a strongly textured face-centered cubic (fcc) structure was formed in the as-deposited state with an average grain size of about 10 nm. Upon annealing, the crystal structure was retained whereas the grain size increased by a factor of 3 to 5, depending on alloy composition. The zero-field resistivity decreased strongly by annealing due to the increased grain size. The annealing hardly changed the AMR below 50 at.% Co but strongly decreased it above this concentration. The composition dependence of the resistivity and the AMR of the annealed Ni-Co alloy deposits was in good quantitative agreement with the available literature data both at 13 K and at room temperature. Both transport parameters were found to exhibit a pronounced maximum in the composition range between 20 and 30 at.% Co and the data of the Ni-Co alloys fitted well to the limiting values of the pure component metals (fcc-Ni and fcc-Co). The only theoretical calculation reported formerly on fcc Ni-Co alloys yielded at T = 0 K a resistivity value smaller by a factor of 5 and an AMR value larger by a factor of about 2 than the corresponding low-temperature experimental data, although the theoretical study properly reproduced the composition dependence of both quantities.     

On the temperature dependence of the electrical resistivity of non-stoichiometric actinide compounds

We suggest that the systematic investigation of the dependence of resistivity upon temperature in non-stoichiometric actinide compounds could bring some information on the possibility of non-Kondo minima in highly resistive systems suggested by a recent theory of Markowitz.     

On the anomalous temperature dependence of the electrical resistivity in liquid alloys

It is demonstrated that the anomalous temperature dependence of the electrical resistivity, as experimentally reported for liquid binary alloys of simple metals, arises primarily from the significant decrease in the partial localization of the valence electrons on the electronegative component.     

T dependence of the high temperature electrical resistivity of metals

Available data is used to show that the high temperature resistivity of a number of metals varies with temperature as T^3/2 in a manner consistent with recent observations of a similar temperature variation for Debye-Waller factors.     

高压下锐钛矿TiO2的电阻率及能带结构的研究

应用在位电阻率测量方法研究高压下锐钛矿TiO2的电学性质。通过研究电阻率随压力变化的异常变化点,观察到了TiO2从锐钛矿－柯铁矿－斜锆石的相变。卸压后,电阻率数值和初始值相差2个数量级,说明该相变为不可逆相变。结合第一性原理计算结果表明,柯铁矿结构更小的带隙是导致TiO2电阻率减小的根本原因。     

高压下锐钛矿TiO2的电阻率及能带结构的研究

应用在位电阻率测量方法研究高压下锐钛矿TiO2的电学性质. 通过研究电阻率随压力变化的异常变化点, 观察到了TiO2从锐钛矿-柯铁矿-斜锆石的相变. 卸压后,电阻率和初始值相差2个数量级, 说明该相变为不可逆相变. 结合第一性原理计算结果表明, 柯铁矿结构更小的带隙是导致TiO2电阻率减小的根本原因.     

An analysis of the temperature and pressure dependence of the electrical resistivity in lead

The volume dependence of the high temperature electrical resistivity has been treated in detail for lead. Volume changes caused by external pressure as well as thermal expansion have been considered. Experiments on the volume dependence of the effective electron mass have been reanalysed with an inclusion of electron-phonon interaction. Finally, we have found no experimental support for a net effect from a Debye-Waller factor and multi-phonon processes.     

Effect of spin-fluctuations on the temperature dependence of electrical resistivity in transition alloys

Two recent theories of spin-fluctuations in metals are generalized to concentrated transition binary alloys. It is shown that in these alloys the effect of spin-fluctuations can give to a negative T-coefficient of resistance d?/dT.     

A study of the temperature and pressure dependence of the electrical resistivity of a dilute Cr-Ge system

The electrical resistivity of a series of dilute Cr-Ge alloys containing up to 1.5 atm % Ge, was measured as a function of temperature and pressure. The measurements clearly demonstrate the existence of resistivity anomalies at the incommensurate-commensurate spin density wave transition temperature (T_IC) in contrast with recently reported results. The complete magnetic phase diagram, determined for the first time from electrical resistivity measurements, contains a triple point in contrast with previous neutron diffraction results but in agreement with thermal expansion measurements. It was found that the incommensurate spin density wave state is absent in alloys with more than 1 atm % Ge. The Néel temperatures and incommensurate-commensurate transition temperatures are affected differently by pressure. Pressure decreases T_N in all the alloys while it increases T_IC for those alloys in which the incommensurate-commensurate transition occurs. The decrease of T_N with pressure is much larger for the commensurate-paramagnetic than for the incommensurate-paramagnetic transition. The electrical resistivity of the alloys at room temperature behaves anomalously with applied pressure. This anomalous behaviour is attributed to an antiferromagnetic-paramagnetic phase transition that is induced in the alloys by applied pressure.     

Temperature dependence of the electrical resistivity in amorphous metals

In amorphous metals the electrical resistivity increases linearly in the temperature range from 2 to 40 K. This result differs fundamentally from the nonlinear behaviour known for crystalline metals and it suggests the conduction electrons not to be scattered by the vibrations of the amorphous point lattice. The temperature dependent part of the resistivity in amorphous metals is explained with scattering of conduction electrons by fluctuations ofp-electrons.     

Confinement effects in electrical resistivity and spin-valve magnetoresistance in metallic layered structures

Quantum size effects in electronic transport properties of metallic trilayers are analysed theoretically. It is shown that electron confinement leads to oscillations in electrical resistivity with two different periodicities. The short oscillation period is determined by the appropriate Fermi wavelength, whereas the long period depends on the potential step at interfaces. When the outer films in the trilayer are ferromagnetic, then the oscillations in the resistivity give rise to similar oscillations in the spin-valve magnetoresistance.     

Temperature dependence of the electrical resistivity of amorphous Pd-Si alloy

Czechoslovak Journal of Physics - The temperature dependence of the electrical resistivity of amorphous binary Pd-Si alloy has been calculated by means of the t-matrix formulation of the extended...