Optical Signatures of Weyl Points in TaAs

TL;DR

This study investigates the optical properties of TaAs, revealing signatures of Weyl points through linear frequency dependence and temperature behavior consistent with Weyl semimetals.

Contribution

It provides the first systematic analysis of the optical response in TaAs, linking experimental signatures to the presence of Weyl points near the Fermi energy.

Findings

Linear optical conductivity with distinct slopes observed

Drude peak width decreases with T^2 dependence

Optical signatures consistent with Weyl points near Fermi energy

Abstract

We present a systematic study of both the temperature and frequency dependence of the optical response in TaAs, a material that has recently been realized to host the Weyl semimetal state. Our study reveals that the optical conductivity of TaAs features a narrow Drude response alongside a conspicuous linear dependence on frequency. The width of the Drude peak decreases upon cooling, following a $T^{2}$ temperature dependence which is expected for Weyl semimetals. Two linear components with distinct slopes dominate the 5-K optical conductivity. A comparison between our experimental results and theoretical calculations suggests that the linear conductivity below $\sim$230~cm$^{-1}$ is a clear signature of the Weyl points lying in very close proximity to the Fermi energy.