Coactive-Staggered Feature in Weyl Materials for Enhancing the Anomalous Nernst Conductivity

TL;DR

This paper introduces a new 'coactive-staggered' feature in Weyl materials that maximizes anomalous Nernst conductivity, proposing methods to engineer such features for improved thermoelectric performance.

Contribution

It identifies the 'coactive-staggered' feature as key to maximizing ANC and proposes practical ways to create and tune this feature in Weyl and Dirac materials.

Findings

Maximal ANC occurs with coactive-staggered AHC features.

Two Weyl pairs arranged minimally can produce this feature.

Tuning Weyl point separations controls the ANC peak temperature.

Abstract

Power generation through the anomalous Nernst effect in topological Weyl materials has several advantages over conventional thermoelectrics due to the transverse geometry. However, the magnitude of the anomalous Nernst conductivity (ANC) in most known materials is too small to be of practical use, and there exist few guiding principles for finding materials with optimal thermoelectric properties. This work shows that the ANC is maximal when there is a ``coactive-staggered" feature in the anomalous Hall conductivity (AHC). It is shown that a minimal arrangement of two Weyl pairs leads to such a feature, and tuning the separations between the pairs controls the temperature at which the ANC is maximal. Several methods are proposed for creating such arrangements of Weyl points starting from Dirac semimetal materials. It is also demonstrated how an existing coactive-staggered AHC in a Heusler material can be exploited, by collectively tuning the positions of the Weyl points through strain to further enhance the ANC. A modest 20% amplification of the ANC is achieved, even with relatively minor changes in Weyl point positions.