# Uncovering Electron-Phonon Scattering and Phonon Dynamics in Type-I Weyl Semimetals

## TL;DR

This study investigates electron-phonon interactions and phonon behavior in type-I Weyl semimetals NbAs and TaAs, revealing new Fano lineshapes and atypical phonon linewidths that influence their transport properties.

## Contribution

It provides the first principles analysis of phonon self-energy corrections and links Fano asymmetry to electron-phonon coupling and Weyl point locations in these materials.

## Key findings

- Observation of a new Fano lineshape in NbAs Raman spectra
- Atypical temperature dependence of phonon linewidths in NbAs and TaAs
- First principles calculations explaining electron-phonon interaction effects

## Abstract

Weyl semimetals are 3D phases of matter with topologically protected states that have remarkable macroscopic transport behaviors. As phonon dynamics and electron-phonon scattering play a critical role in the electrical and thermal transport, we pursue a fundamental understanding of the origin of these effects in type-I Weyl semimetals NbAs and TaAs. In the temperature-dependent Raman spectra of NbAs, we reveal a previously unreported Fano lineshape, a signature stemming from the electron-phonon interaction. Additionally, the temperature dependence of the $A_{1}$ phonon linewidths in both NbAs and TaAs strongly deviate from the standard model of anharmonic decay. To capture the mechanisms responsible for the observed Fano asymmetry and the atypical phonon linewidth, we present first principles calculations of the phonon self-energy correction due to the electron-phonon interaction. Finally, we investigate the relationship between Fano lineshape, electron-phonon coupling, and locations of the Weyl points in these materials. Through this study of the phonon dynamics and electron-phonon interaction in these Weyl semimetals, we consider specific microscopic pathways which contribute to the nature of their macroscopic transport.