Fig. 5.

Three-dimensional nature of Rashba-like bands around M point. a–d Energy–momentum image mapped by angle-resolved photoemission spectroscopy (ARPES) taken at different photon energies. e Band dispersion along M–L direction obtained by plotting energy distribution curves at the M point taken at different photon energies as function of k_z (the M–L direction as sketched in the three-dimensional Brillouin zone shown in the inset). f Calculated band structure of PtBi₂ along the in-plane and out-of-plane momentum directions. The red and blue solid lines show the in-plane band structures at different k_z. The red and green dashed lines show the band dispersions along k_z direction, indicating Rashba splitting along k_z. g Sketch of Rashba bands which have dispersion along k_z but remain spin degenerate along k_z for k_x = k_y = 0