Weyl fermions induced magnon electrodynamics in a Weyl semimetal

Weyl fermions, which are fermions with definite chiralities, can give rise to anomalous breaking of the symmetry of the physical system that they are a part of. In their (3+1)-dimensional realizations in condensed matter systems, i.e., the so-called Weyl semimetals, this anomaly gives rise to topological electromagnetic response of magnetic fluctuations, which takes the form of nonlocal interaction between magnetic fluctuations and electromagnetic fields. We study the physical consequences of this nonlocal interaction, including electric field assisted magnetization dynamics, an extra gapless magnon dispersion, and polariton behaviors that feature "sibling" bands in small magnetic fields.