Optical Signatures of the Chiral Anomaly in Mirror-Symmetric Weyl Semimetals

The chiral anomaly is a phenomenon characteristic of Weyl fermions, which has condensed matter realizations in Weyl semimetals. Efforts to observe a smoking gun signatures of the chiral anomaly in Weyl semimetals have so far focused on a negative magnetoresistance in electronic transport. Unfortunately, disentangling the chiral anomaly contribution in transport measurements has proven non-trivial. Recent works have proposed an alternative approach of probing phonon dynamics for signatures of the chiral anomaly in non-mirror-symmetric crystals. Here, we show that such phononic signatures can be extended to mirror symmetric crystals, broadening the pool of candidate materials. We show that the background magnetic field can break mirror symmetry strongly enough to yield observable signatures of chiral anomaly even in mirror-symmetric materials. Specifically for mirror-symmetric Weyl semimetals such as TaAs and NbAs, including the Zeeman interaction at B~10T, we predict an IR reflectance peak will develop with an E_IR●B dependence.