Large Nernst effect in Te-based van der Waals materials

TL;DR

This study systematically investigates the Nernst effect in Te-based van der Waals Weyl semimetals, revealing large linear Nernst coefficients linked to mobility and highlighting their potential for thermoelectric applications.

Contribution

It provides the first comprehensive comparison of Nernst effects across multiple telluride van der Waals materials, identifying correlations with electronic structure and mobility.

Findings

Large linear Nernst coefficients in WTe₂ and MoTe₂.

Moderate, non-linear Nernst effects in other tellurides.

Correlation between linear Nernst component and mobility.

Abstract

Layered van der Waals tellurides reveal topologically non-trivial properties that give rise to unconventional magneto-transport phenomena. Additionally, their semimetallic character with high mobility makes them promising candidates for large magneto-thermoelectric effects. Remarkable studies on the very large and unconventional Nernst effect in WTe$_2$ have been reported, raising questions about whether this property is shared across the entire family of van der Waals tellurides. In this study, systematic measurements of the Nernst effect in telluride van der Waals Weyl semimetals are presented. Large linear Nernst coefficients in WTe$_2$ and MoTe$_2$ are identified, and moderate Nernst coefficients with non-linear behavior in magnetic fields are observed in W$_{0.65}$Mo$_{0.35}$Te$_2$, TaIrTe$_4$, and TaRhTe$_4$. Within this sample set, a correlation between the dominant linear-in-magnetic-field component of the Nernst coefficient and mobility is established, aligning with the established Nernst scaling framework, though with a different scaling factor compared to existing literature. This enhancement might be caused by the shared favorable electronic band structure of this family of materials. Conversely, the non-linear component of the Nernst effect in a magnetic field could not be correlated with mobility. This non-linear term is almost absent in the binary compounds, suggesting a multiband origin and strong compensation between electron-like and hole-like carriers. This comprehensive study highlights the potential of van der Waals tellurides for thermoelectric conversion.