Transport properties near the Anderson transition

The electronic transport properties in the presence of a temperature gradient in disordered systems near the metal-insulator transition [MIT] are considered. The d.c. conductivity $\sigma$, the thermoelectric power $S$, the thermal conductivity $K$ and the Lorenz number $L_0$ are calculated for the three-dimensional Anderson model of localization using the Chester-Thellung-Kubo-Greenwood formulation of linear response. We show that $\sigma$, S, K and $L_0$ can be scaled to one-parameter scaling curves with a single scaling paramter $k_BT/|{\mu-E_c}/E_c|$.Comment: 4 pages, 4 EPS figures, uses annalen.cls style [included]; presented at Localization 1999, to appear in Annalen der Physik [supplement

Thermoelectric Transport Properties in Disordered Systems Near the Anderson Transition

We study the thermoelectric transport properties in the three-dimensional Anderson model of localization near the metal-insulator transition [MIT]. In particular, we investigate the dependence of the thermoelectric power S, the thermal conductivity K, and the Lorenz number L_0 on temperature T. We first calculate the T dependence of the chemical potential from the number density of electrons at the MIT using averaged density of state obtained by diagonalization. Without any additional approximation, we determine from the chemical potential the behavior of S, K and L_0 at low T as the MIT is approached. We find that the d.c. conductivity and K decrease to zero at the MIT as T -> 0 and show that S does not diverge. Both S and L_0 become temperature independent at the MIT and depend only on the critical behavior of the conductivity.Comment: 11 pages, 10 eps figures, coded with the EPJ macro package, submitted to EPJ

Optimizing thermal transport in the Falicov-Kimball model: binary-alloy picture

We analyze the thermal transport properties of the Falicov-Kimball model concentrating on locating regions of parameter space where the thermoelectric figure-of-merit ZT is large. We focus on high temperature for power generation applications and low temperature for cooling applications. We constrain the static particles (ions) to have a fixed concentration, and vary the conduction electron concentration as in the binary-alloy picture of the Falicov-Kimball model. We find a large region of parameter space with ZT>1 at high temperature and we find a small region of parameter space with ZT>1 at low temperature for correlated systems, but we believe inclusion of the lattice thermal conductivity will greatly reduce the low-temperature figure-of-merit.Comment: 13 pages, 14 figures, typeset with ReVTe

Persistent spin splitting of a two-dimensional electron gas in tilted magnetic fields

By varying the orientation of the applied magnetic field with respect to the normal of a two-dimensional electron gas, the chemical potential and the specific heat reveal persistent spin splitting in all field ranges. The corresponding shape of the thermodynamic quantities distinguishes whether the Rashba spin-orbit interaction RSOI, the Zeeman term or both dominate the splitting. The interplay of the tilting of the magnetic field and RSOI resulted to an amplified splitting in weak fields. The effects of changing the RSOI strength and the Landau level broadening are also investigated.Comment: 10 pages, 5 figure

The Interplay of Landau Level Broadening and Temperature on Two-Dimensional Electron Systems

This work investigates the influence of low temperature and broadened Landau levels on the thermodynamic properties of two-dimensional electron systems. The interplay between these two physical parameters on the magnetic field dependence of the chemical potential, the specific heat and the magnetization is calculated. In the absence of a complete theory that explains the Landau level broadening, experimental and theoretical studies in literature perform different model calculations of this parameter. Here it is presented that different broadening parameters of Gaussian-shaped Landau levels cause width variations in their contributions to interlevel and intralevel excitations. Below a characteristic temperature, the interlevel excitations become negligible. Likewise, at this temperature range, the effect of the Landau level broadening vanishes.Comment: 5 pages, 5 figures, submitted to Solid State Communication

Behavior of the thermopower in amorphous materials at the metal-insulator transition

We study the behavior of the thermal transport properties in three-dimensional disordered systems close to the metal-insulator transition within linear response. Using a suitable form for the energy-dependent conductivity , we show that the value of the dynamical scaling exponent for noninteracting disordered systems such as the Anderson model of localization can be reproduced. Furthermore, the values of the thermopower S have the right order of magnitude close to the transition as compared to the experimental results. A sign change in the thermoelectric power S -as is often observed in experiments -can also be modeled within the linear response formulation using modified experimental data as input

Behavior of the thermopower in amorphous materials at the metal-insulator transition

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