Thickness dependence of the anomalous Nernst effect and the Mott relation of Weyl-semimetal Co2MnGa thin films

TL;DR

This study investigates the thickness-dependent anomalous Nernst effect in Co2MnGa Weyl semimetal thin films, demonstrating the validity of the Mott relation and the dominance of Berry curvature in transport properties.

Contribution

It provides the first comprehensive analysis linking the anomalous Nernst effect, Hall effect, and Mott relation in Co2MnGa thin films across different thicknesses.

Findings

Anomalous Nernst coefficient ranges from -2.0 to -3.0 μV/K at 300 K.

The Mott relation holds for the transport coefficients in these films.

Berry curvature dominates the magneto-thermal transport in the material.

Abstract

We report a robust anomalous Nernst effect in Co2MnGa thin films in the thickness regime between 20 and 50 nm. The anomalous Nernst coefficient varied in the range of -2.0 to -3.0 uV/K at 300 K. We demonstrate that the anomalous Hall and Nernst coefficients exhibit similar behavior and fulfill the Mott relation. We simultaneously measure all four transport coefficients of the longitudinal resistivity, transversal resistivity, Seebeck coefficient, and anomalous Nernst coefficient. We connect the values of the measured and calculated Nernst conductivity by using the remaining three magneto-thermal transport coefficients, where the Mott relation is still valid. The intrinsic Berry curvature dominates the transport due to the relation between the longitudinal and transversal transport. Therefore, we conclude that the Mott relationship is applicable to describe the magneto-thermoelectric transport in Weyl semimetal Co2MnGa as a function of film thickness.