Influence of Landau levels in the phonon dispersion of Weyl semimetals

Discovered in high-energy physics, the chiral anomaly has recently made way to materials science by virtue of Weyl semimetals (WSM). Thus far, the main efforts to probe the chiral anomaly in WSM have concentrated on electronic phenomena. Nevertheless, recent theoretical works [1,2] have studied signatures of the chiral anomaly in the dynamics of lattice vibrations, to first order in the external magnetic field. In this work, we generalize those earlier results to magnetic fields of arbitrary strength by incorporating the influence of Landau levels in the phonon spectra. We predict a hybridization between plasmons and optical phonons that becomes potentially observable at high magnetic fields, and we identify fingerprints of chiral Landau levels in the sound velocity.

[1] Z. Song, J. Zhao, Z. Fang and X. Dai, Phys. Rev. B 94, 214306 (2016).

[2] P. Rinkel, P. L. S. Lopes and I. Garate, Phys. Rev. Lett. 119, 107401 (2017).