ARPES and spin ARPES measurements of nonmagnetic centrosymmetric crystal LaBiOS$_{2}$

Spin polarized bands are traditionally expected to exist only under global bulk symmetry breaking. LaBiOS$_{2}$ has a centrosymmetric structure thus expected to have no spin polarization. However, it is predicted to have local inversion-asymmetric structure, leading to spin polarization localized on the individual BiS$_{2}$ sublayers. This spin polarization theoretically presents itself in energetically doubly degenerate bands that are spatially separated on different BiS$_{2}$ layers. We measured ARPES and spin ARPES on the inversion-symmetric bulk crystal LaBiOS$_{2}$ in search of such a hidden spin polarization. Our measurements show band structure to have qualitative agreement with DFT calculations. We additionally observe spin polarization in the valence band and will discuss its spin orientation in this talk. This work is supported by NSF DMREF project 1334170.