# Fermi arc mediated entropy transport in topological semimetals

## TL;DR

This paper predicts that Fermi arcs in Weyl semimetals cause a unique, anisotropic magnetothermal conductivity driven by circulating entropy currents, offering a new experimental signature of topological surface states.

## Contribution

It introduces the first theoretical proposal linking Fermi arcs to measurable thermal transport signatures in Weyl semimetals.

## Key findings

- Analytical calculation of Fermi arc-mediated magnetothermal conductivity in low and high magnetic fields.
- Numerical analysis showing the connection between different magnetic field regimes.
- Identification of a unique experimental signature for Fermi arcs via thermal transport.

## Abstract

In topological Weyl semimetals, the low energy excitations are comprised of linearly dispersing Weyl fermions, which act as monopoles of Berry curvature in momentum space and result in topologically protected Fermi arcs on the surfaces. We propose that these Fermi arcs in Weyl semimetals lead to an anisotropic magnetothermal conductivity, strongly dependent on externally applied magnetic field and resulting from entropy transport driven by circulating electronic currents. The circulating currents result in no net charge transport, but they do result in a net entropy transport. This translates into a magnetothermal conductivity that should be a unique experimental signature for the existence of the arcs. We analytically calculate the Fermi arc-mediated magnetothermal conductivity in the low-field semiclassical limit as well as in the high-field ultra-quantum limit, where only the chiral Landau levels are involved. By numerically including the effects of higher Landau levels, we show how the two limits are linked at intermediate magnetic fields. This work provides the first proposed signature of Fermi arc-mediated thermal transport and sets the stage for utilizing and manipulating the topological Fermi arcs in experimental thermal applications.