Absorption of circular polarized light in tilted type-I and type-II Weyl semimetals

We calculate the ac optical response to circularly polarized light of a Weyl semimetal (WSM) with varying amounts of tilt of the Dirac cones. Both type-I and -II (overtilted) WSMs are considered in a continuum model with broken time-reversal symmetry. The Weyl nodes appear in pairs of equal energies but of opposite momentum and chirality. For type I, the response of a particular node to right-hand polarized (RHP) and left-hand polarized (LHP) light is distinct only in a limited range of photon energy Omega 2/1+C-2/v < Omega/mu < 2/1-C-2/v with mu the chemical potential and 2 the tilt associated with the positive chirality node assuming the two nodes are oppositely tilted. For the overtilted case (type II), the same lower bound applies but there is no upper bound. If the tilt is reversed, the RHP and LHP responses are also reversed. We present corresponding results for the Hall angle.