Chiral anomaly induced nonlinear Nernst and thermal Hall effects in Weyl semimetals

TL;DR

This paper predicts new nonlinear thermoelectric effects in Weyl semimetals caused by chiral anomaly, deriving analytical formulas and suggesting they can be observed experimentally in realistic materials.

Contribution

It introduces the concept of nonlinear planar Nernst and thermal Hall effects induced by chiral anomaly in Weyl semimetals, with analytical derivations and broader applicability.

Findings

Derived analytical expressions for nonlinear Nernst and thermal Hall coefficients.

Showed effects can exist in various Weyl semimetal configurations.

Predicted experimental realizability of these effects.

Abstract

Chiral anomaly or Adler-Bell-Jackiw anomaly in Weyl semimetals (WSMs) has a significant impact on the electron transport behaviors, leading to remarkable longitudinal or planar electrical and thermoelectric transport phenomena in the presence of electromagnetic gauge fields. These phenomena are consequences of the imbalanced chiral charge and energy induced by chiral anomaly in the presence of parallel electric ($\mathbf{E}$) and magnetic ($\mathbf{B}$) fields ($\mathbf{E \cdot B }\neq 0$) or $(\mathbf{B \cdot \nabla }T\neq 0)$ ($\mathbf{\nabla}T$ is the thermal gradient). We here propose another two fascinating transport properties, namely, the nonlinear planar Nernst effect and nonlinear planar thermal Hall effect induced by chiral anomaly in the presence of $\mathbf{B \cdot \nabla}T\neq 0$ in WSMs. Using the semiclassical Boltzmann transport theory, we derive the analytical expressions for the chiral anomaly induced nonlinear Nernst and thermal Hall transport coefficients and also evaluate the fundamental mathematical relations among them in the nonlinear regime. The formulas we find in this current work are consistent with that predicted for the nonlinear anomalous electrical and thermoelectric effects induced by Berry curvature dipole recently. Additionally, in contrast to the recent work, by utilizing the lattice Weyl Hamiltonian with intrinsic chiral chemical potential, we find that the chiral anomaly induced nonlinear planar effects can exist even for a pair of oppositely tilted or non-tilted Weyl cones in both time reversal and inversion broken WSMs. The chiral anomaly induced nonlinear planar effects predicted here along with the related parameter dependencies are hence possible to be realized in realistic WSMs in experiment.