Thermoelectric Properties of Disordered Systems

TL;DR

This paper investigates the thermoelectric properties of disordered systems using a Green's function recursion algorithm, revealing insights into thermopower fluctuations and their implications for quantum effects at low temperatures.

Contribution

It introduces a novel Green's function recursion method to compute thermoelectric coefficients in disordered systems, including the Lorenz number and thermopower distribution.

Findings

Lorentzian distribution observed for thermopower

Inelastic scattering modifies thermopower distribution

Potential quantum fluctuations in macroscopic systems at low temperatures

Abstract

The electronic properties of disordered systems have been the subject of intense study for several decades. Thermoelectric properties, such as thermopower and thermal conductivity, have been relatively neglected. A long standing problem is represented by the sign of the thermoelectric power. In crystalline semiconductors this is related to the sign of the majority carriers, but in non-crystalline systems it is commonly observed to change sign at low temperatures. In spite of its apparent universality this change has been interpreted in a variety of ways in different systems. We have developed a Green's function recursion algorithm based on the Chester-Thelling-Kubo-Greenwood formula for calculating the kinetic coefficients on long strips or bars. From these we can deduce the electrical conductivity, the Seebeck and Peltier coefficients and the thermal conductivity, as well as the Lorenz number. We present initial results for 1D systems. We observe a Lorentzian distribution for the thermopower which is modified by the presence of inelastic scattering. This could give rise to non-negligible quantum fluctuations in macroscopic systems at low temperatures.