Thermoelectric effects in topological crystalline insulators

TL;DR

This paper explores the electrical and thermoelectric properties of topological crystalline insulators, revealing how impurity interactions and band structure features influence conductivity and Seebeck effects.

Contribution

It introduces a generalized Boltzmann approach to analyze anisotropic Fermi surfaces and uncovers the impact of Van Hove singularities and interband scattering on thermoelectric behavior.

Findings

Conductivity shows a local minimum at doping levels near Van Hove singularities.

Suppression of interband scattering leads to a maximum in electrical conductivity.

Seebeck coefficient changes sign at extremal points in conductivity.

Abstract

We investigate the electrical conductivity and thermoelectric effects in topological crystalline insulators in the presence of short- and long-range impurity interactions. We employ the generalized Boltzmann formalism for anisotropic Fermi surface systems. The conductivity exhibits a local minimum as doping varies owing to the Van Hove singularity in the density of states originated from the saddle point in the surface states band structure. Suppression of the interband scattering of the charge carriers at high-energy Dirac points results in a maximum in the electrical conductivity. Whenever the Fermi level passes an extremum in the conductivity, Seebeck coefficient changes sign. In addition, it is revealed that profound thermoelectric effects can be attained around these extrema points.