Probing electron-phonon interactions in Weyl semimetal using Raman spectroscopy and anharmonic phonon calculations

TaP, a type of Weyl semimetal (WSM) with noncentrosymmetric space group I4₁md, is a special type of quantum materials that have attracted strong recent interests. The gapless band structure of TaP allows unique optical response and transport phenomena. Although electrical and photoemission characterizations such as Hall measurement and angle-resolved photoemission spectroscopy (ARPES) have been performed on various WSMs, there is insufficient research on the electronic and optical properties using optical spectroscopies as probes. In the present work, the light-matter interactions, including electron-phonon and electron-photon interactions, have been studied comprehensively through phonon-based Raman spectroscopy and first-principles calculations. We demonstrate how the optical spectroscopic responses, such as Raman and absorption, of TaP change under various physical parameters including crystal orientation, temperature, and excitation laser energies. Advanced first-principles calculations of electronic and especially anharmonic phonon properties have been employed to unveil the measured optical spectroscopic responses and their relationship with electronic performance of WSMs.