Berry phase effect in anomalous thermoelectric transport

TL;DR

This paper develops a theoretical framework for Berry phase effects in anomalous thermoelectric transport in ferromagnets, linking microscopic Berry curvature to measurable thermoelectric responses and validating with experimental data.

Contribution

It introduces a finite-temperature orbital magnetization formula and explicit expressions for thermoelectric conductivities, connecting Berry phase effects to observable phenomena.

Findings

Derived a finite-temperature formula for orbital magnetization.

Established the Mott relation and Onsager reciprocity for thermoelectric effects.

Quantitative agreement with experimental data for CuCr2Se4-xBrx.

Abstract

We develop a theory of Berry phase effect in anomalous transport in ferromagnets driven by statistical forces such as the gradient of temperature or chemical potential. Here a charge Hall current arises from the Berry phase correction to the orbital magnetization rather than from the anomalous velocity which does not exist in the absence of a mechanical force. A finite-temperature formula for the orbital magnetization is derived, which enables us to provide an explicit expression for the off-diagonal thermoelectric conductivity, to establish the Mott relation between the anomalous Nernst and Hall effects, and to reaffirm the Onsager relations between reciprocal thermoelectric conductivities. A first-principles evaluation of our expression is carried out for the material CuCr$_2$Se$_{4-x}$Br$_x$, obtaining quantitative agreement with a recent experiment.