Quantum kinetic theory of nonlinear thermal current

TL;DR

This paper develops a quantum kinetic theory to describe nonlinear thermal currents induced by temperature gradients, revealing intrinsic contributions linked to band geometry that occur only when certain symmetries are broken.

Contribution

The paper introduces a new quantum kinetic framework for nonlinear thermal transport, identifying intrinsic, scattering time independent thermal currents related to band geometry.

Findings

Intrinsic thermal current depends on band geometric quantities.

Intrinsic current exists only when both inversion and time-reversal symmetries are broken.

Distinct temperature dependencies of current contributions at low temperature.

Abstract

We investigate the second-order nonlinear electronic thermal transport induced by temperature gradient. We develop the quantum kinetic theory framework to describe thermal transport in presence of a temperature gradient. Using this, we predict an intrinsic scattering time independent nonlinear thermal current in addition to the known extrinsic nonlinear Drude and Berry curvature dipole contributions. We show that the intrinsic thermal current is determined by the band geometric quantities and is non-zero only in systems where both the space inversion and time-reversal symmetries are broken. We employ the developed theory to study the thermal response in tilted massive Dirac systems. We show that besides the different scattering time dependence, the various current contributions have distinct temperature dependence in the low temperature limit. Our systematic and comprehensive theory for nonlinear thermal transport paves the way for future theoretical and experimental studies on intrinsic thermal responses.