Anomalous electromagnetic field transmission and reflection in Weyl and Dirac semimetals

The current response to an electromagnetic field in a Weyl or Dirac semimetal becomes nonlocal due to the chiral anomaly activated by an applied magnetic field. The nonlocality develops under the conditions of the normal skin effect and is related to the valley charge imbalance generated by the joint effect of the electric field of the impinging wave and the static magnetic field. The length scale for the nonlocality is determined by the diffusion length of the valley charge imbalance, which does not violate the local electric charge neutrality. We predict that the signatures of this nonlocality can be found in the transmission and reflection of electromagnetic waves. In view of a weaker decay of the anomalous components in the nonlocal regime, it is possible to achieve an enhancement of the electromagnetic wave penetration depth. In the reflection of electromagnetic waves, the chiral anomaly leads to the decrease of the dissipative part of the surface impedance with the magnetic field; these anomalous effects are reduced in the nonlocal regime.