Heat transport in Weyl semimetals in the hydrodynamic regime

TL;DR

This paper investigates heat transport in Weyl semimetals within the hydrodynamic regime, revealing how electric and heat conductivities, Seebeck effects, and Hall conductivity influence thermal transport properties near the neutrality point.

Contribution

It provides a detailed analysis of thermoelectric and heat transport phenomena in Weyl semimetals, highlighting the interplay between electric conductivity, Seebeck effect, and Hall conductivity in the hydrodynamic regime.

Findings

Longitudinal heat conductivity is governed by momentum relaxation time at neutrality.

Large longitudinal Lorenz ratio occurs in the hydrodynamic regime.

Seebeck effect significantly influences heat conductivity and Lorenz ratio.

Abstract

We study heat transport in a Weyl semimetal with broken time-reversal symmetry in the hydrodynamic regime. At the neutrality point, the longitudinal heat conductivity is governed by the momentum relaxation (elastic) time, while longitudinal electric conductivity is controlled by the inelastic scattering time. In the hydrodynamic regime this leads to a large longitudinal Lorenz ratio. As the chemical potential is tuned away from the neutrality point, the longitudinal Lorenz ratio decreases because of suppression of the heat conductivity by the Seebeck effect. The Seebeck effect (thermopower) and the open circuit heat conductivity are intertwined with the electric conductivity. The magnitude of Seebeck tensor is parametrically enhanced, compared to the non-interacting model, in a wide parameter range. While the longitudinal component of Seebeck response decreases with increasing electric anomalous Hall conductivity $\sigma_{xy}$, the transverse component depends on $\sigma_{xy}$ in a non-monotonous way. Via its effect on the Seebeck response, large $\sigma_{xy}$ enhances the longitudinal Lorenz ratio at a finite chemical potential. At the neutrality point, the transverse heat conductivity is determined by the Wiedemann-Franz law. Increasing the distance from the neutrality point, the transverse heat conductivity is enhanced by the transverse Seebeck effect and follows its non-monotonous dependence on $\sigma_{xy}$.