Photonic spin Hall effect on the surfaces of type-I and type-II Weyl semimetals

Topological optics is an emerging research area in which various topological and geometrical ideas are being proposed to design and manipulate the behaviors of photons. Here, the photonic spin Hall effect on the surfaces of topological Weyl semimetal (WSM) films was studied. Our results show that the spin-dependent splitting (i.e. photonic spin Hall shifts) induced by the spinp-orbit interaction is little sensitive to the tilt alpha(t) of Weyl nodes and the chemical potential mu in type-I WSM film. In contrast, photonic spin Hall shifts in both the in-plane and transverse directions present versatile dependent behaviors on the alpha(t) and mu in type-II WSM film. In particular, the largest in-plane and transverse spin flail shifts appear at the tilts between -2 and -3, which are similar to 40 and similar to 10 times of the incident wavelength, respectively. Nevertheless, the largest spin Hall shifts for type-H WSM film with positive alpha(t) are only several times of incident wavelength. Moreover, the photonic spin Hall shifts also exhibit different variation trends with decreasing the chemical potential for different signs of alpha(t) in type-II WSM films. This dependence of photonic spin Hall shifts on tilt orientation in type-II WSM films has been explained by time-reversal-symmetry-breaking Hall conductivities in WSMs.