Thermoelectric and Seebeck coefficients of granular metals

TL;DR

This paper derives the thermoelectric properties of granular metals at high tunneling conductance, highlighting how electron interactions and grain size influence thermopower and the figure of merit for low-temperature thermoelectric applications.

Contribution

It provides a theoretical derivation of thermopower and thermoelectric coefficients in granular metals, emphasizing the effects of electron interactions and system parameters at intermediate temperatures.

Findings

Thermopower increases with decreasing grain size due to electron-electron interactions.

The figure of merit depends on grain size, tunneling conductance, and temperature.

Results are valid for intermediate temperature regimes where E_c>>T/g_T>δ.

Abstract

In this work we present a detailed study and derivation of the thermopower and thermoelectric coefficient of nano-granular metals at large tunneling conductance between the grains, g_T>> 1. An important criterion for the performance of a thermoelectric device is the thermodynamic figure of merit which is derived using the kinetic coefficients of granular metals. All results are valid at intermediate temperatures, E_c>>T/g_T>\delta, where \delta is the mean energy level spacing for a single grain and E_c its charging energy. We show that the electron-electron interaction leads to an increase of the thermopower with decreasing grain size and discuss our results in the light of future generation thermoelectric materials for low temperature applications. The behavior of the figure of merit depending on system parameters like grain size, tunneling conductance, and temperature is presented.