  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.
