Anomalous transfer of chirality from light to fermions in Dirac and Weyl semimetals

Circularly polarized light possesses a non-zero chirality since it breaks the symmetry between left and right. When circularly polarized light interacts with Dirac and Weyl semimetals, we predict that chirality will be transferred from the electromagnetic field to the chiral quasiparticles in the semimetal. We show that if the photoresponse of the material is dominated by chiral quasiparticles, the total chiral charge induced in the material by light can be evaluated in a model-independent way through the chiral anomaly. In the presence of an external magnetic field, this would result in a photocurrent due to the chiral magnetic effect. The predicted photocurrent should manifest in any kind of Dirac or Weyl semimetal, with both symmetric and asymmetric band structure. This current scales linearly with the magnetic field and wavelength, opening up the possibility for a wide range of applications.