Influence of disorder on the transport properties of heavy-fermion systems

TL;DR

This paper investigates how substitutional disorder affects transport properties in heavy-fermion systems using an extended dynamical mean-field theory approach, revealing key concentration-dependent behaviors and sign changes in thermoelectric properties.

Contribution

It introduces a coherent-potential approximation within dynamical mean-field theory to study disordered strongly correlated electron systems, specifically applied to the periodic Anderson model.

Findings

Reproduces magnitude and concentration dependence of transport properties in heavy-fermion systems.

Observes sign changes in the Seebeck coefficient with temperature and concentration.

Provides spectral functions and self-energies for disordered heavy-fermion models.

Abstract

The influence of substitutional disorder on the transport properties of heavy-fermion systems is investigated. We extend the dynamical mean-field theory treatment of the periodic Anderson model (PAM) to a coherent-potential approximation for disordered strongly correlated electron systems. Considering two distinct local environments of a binary alloy $A_c B_{1-c}$ with arbitrary concentration $c$, we explore two types of disorder: on the f site and on the ligand sites. We calculate the spectral functions and self-energies for the disordered PAM as well as the temperature dependence of the resistivity and the thermoelectric power. The characteristic concentration dependence as well as the order of magnitude of transport properties are reproduced for metallic heavy-fermion systems and Kondo insulators. In particular, sign changes of the Seebeck coefficient as function of temperature and concentration are observed.