Kaganov-Lifshitz-Tanatarov theory for tilted Dirac-cone materials: anisotropic heating from uniform light

TL;DR

This paper reveals that in tilted Dirac cone materials, electron-phonon relaxation causes anisotropic heating, which can be controlled externally and has potential applications in ultrafast sensors and transient thermoelectric effects.

Contribution

It introduces a theoretical framework showing anisotropic electron relaxation and heating in tilted Dirac materials, enabling control of thermal effects via external pressure.

Findings

Anisotropic electron-phonon relaxation in tilted Dirac materials.

Transient anisotropic heating can induce a Seebeck effect.

External pressure can tune the direction of anisotropic heating.

Abstract

We point out that in the tilted Dirac cone materials the non-equilibrium (hot) electron relaxation with phonons is anisotropic in the Brillouin zone. It means that there is a preferential heating of the lattice degrees of freedom in the specific directions of the Brillouin zone, in particular, in the direction opposite to the tilt velocity in the model considered by us. This observation will have novel consequences: (1) With pump-probe spectroscopy applied to a given tilted Dirac cone material an anisotropic relaxation would lead to a transient anisotropic heating which can further lead to a transient Seebeck effect as transient thermal gradients would exist in the specific directions of the BZ, and (2) this direction of anisotropic heating can be controlled by controlling the direction of the tilt velocity which can be externally tuned by the application of an external pressure. We foresee novel applications of this effect in ultrafast sensor applications involving transient heating effects. This is equivalent to inducing a transient Seebeck effect by just shinning light on a tilted Dirac cone material!