Tilting effect in magneto-absorption of Weyl semimetals*

In Weyl semimetals (WSMs), the conduction and valence bands touch at discrete points (Weyl points) in the momentum space with linear dispersed bands around them in all directions. In realistic WSMs, such as NbP, NbAs, TaP, and TaAs, the Weyl bands are tilted, which challenges the application of the previous effective Hamiltonian model in analyzing the magneto-absorption spectra. For instance, tilting is expected to break the axial symmetry of the Weyl band and thus the selection rules for magneto-optical transitions. In this talk, we will examine the tilting effect by constructing a more practical effective Hamiltonian model, incorporating band tilting, asymmetry, and parabolic terms in the band structure. We numerically calculate the Landau levels of WSM in magnetic field in different orientations, from which we obtain the magneto-absorption spectra using Fermi’s golden rule. We extract the tilting effect by comparing our numerical results with the effective Hamiltonian model without tilting.