Thermal transport properties of a charge density wave

TL;DR

This paper investigates how collective modes influence thermoelectric and thermal transport in charge density wave systems, deriving temperature-dependent behaviors using linear response theory and highlighting the role of nonlinear interactions.

Contribution

It provides a theoretical analysis of thermoelectric and thermal transport properties in charge density waves, emphasizing the impact of nonlinear amplitude-phase interactions on temperature dependence.

Findings

Thermoelectric power is inversely proportional to temperature.

Thermal conductivity remains nearly constant above the amplitude mode gap.

Thermal conductivity drops exponentially below the amplitude mode gap.

Abstract

Effects of collective modes on thermoelectric properties of a charge density system is studied. We derive the temperature dependence of thermoelectric power and thermal conductivity by applying the linear response theory to Fr\"ohlich Hamiltonian. Energy dissipation has been attributed to non-linear interaction between phase mode and amplitude mode, ignoring disorder effects. We have found that the temperature dependence of the correlation function of electrical and heat currents is the same as that of electrical conductivity. This implies that thermoelectric power is inversely proportional to temperature. We have also found that temperature dependence of all the correlation functions are essentially determined by the common mechanism - nonlinear amplitude-phase interaction. Thermal conductivity has nearly constant value at the temperature above amplitude mode gap, and has exponentially low value at the temperature sufficiently below it.