Landau level spectrum and magneto-optical conductivity in tilted Weyl semimetal br

We present a systematic investigation of the magnetoresponses of the Weyl points (WPs) with a topologicalcharge ofn=2,3, and 4, and with both linear and quadratic energy tilt. The linear tilt always tends to squeezethe Landau levels (LLs) of both conduction and valence bands of all the WPs, and eventually leads to LLcollapse in the type-II phase. However, the quadratic energy tilt has more complex influences on the LLs of theunconventional WPs. For charge-n(n=2,4) WP, the influence of the quadratic tilt on the LLs of conduction andvalence bands are opposite, i.e., if the LLs of conduction (valence) bands are squeezed, then that of the valence(conduction) bands are broadened and the squeezed LL spectrum will be collapsed in the type-III phase. But, theLL collapse generally cannot be found in the type-III charge-3 WP. Moreover, for charge-n(n=2,3) WP, thequadratic tilt breaks the degeneracy of the chiral LLs regardless of the direction of the magnetic field, leading toadditional optical transitions and magneto-optical conductivity peaks at low frequencies. Interestingly, the fourchiral LLs in charge-4 WP are always not degenerate. Hence there inevitably exist magneto-optical conductivitypeaks at low frequencies for charge-4 WP. Since the density of state of the LL spectrum is very large, one canexpect that the low-frequency magneto-optical responses in unconventional WPs would be significant and maybe used for developing efficient terahertz photodetectors