Phonon-limited Transport and Fermi Arc Lifetime in Weyl Semimetals

TL;DR

This paper investigates how acoustic phonons affect the decay rate and conductivity of Fermi arc states in Weyl semimetals, revealing temperature-dependent behaviors and anisotropic transport properties.

Contribution

It provides a detailed theoretical analysis of phonon-induced quasiparticle decay and conductivity in Weyl semimetals, including the effects of Fermi arc geometry and slab dimensions.

Findings

Quasiparticle decay rate varies with temperature and proximity to arc termination points.

Longitudinal conductivity along the chiral direction is enhanced at low temperatures.

A 1/T^2 scaling regime appears at intermediate temperatures for the conductivity.

Abstract

Weyl semimetals harbor topological Fermi-arc surface states which determine the nontrivial charge current response to external fields. We here study the quasiparticle decay rate of Fermi arc states arising from their coupling to acoustic phonons, as well as the phonon-limited conductivity tensor for a clean Weyl semimetal slab. Using the phonon modes for an isotropic elastic continuum with a deformation potential coupling to electrons, we determine the temperature dependence of the quasiparticle decay rate, both near and far away from the arc termination points. By solving the coupled Boltzmann equations for the bulk and arc state distribution functions in the slab geometry, we show how the linear response conductivity depends on key parameters such as the temperature, the chemical potential, the geometric shape of the Fermi arcs, or the slab width. The chiral nature of Fermi arc states causes an enhancement of the longitudinal conductivity along the chiral direction at low temperatures, together with a 1/T^2 scaling regime at intermediate temperatures without counterpart for the conductivity along the perpendicular direction.