Protected Hidden Spin Polarization by Crystalline Symmetry in Centrosymmetric Nonmagnetic Systems

We derive a tight-binding model with spin-orbital interaction to describe the band edge behaviors of a two-dimensional centrosymmetric system with non-symmorphic symmertry. The two sublattices in this structure are staggered along the normal direction, and connect each other by glide reflection operations, which plays an essential role in protecting the local Rashba spin polarization for each sublattice. By model simulation and symmetry analyses, we find that each sublattice hosts a Rashba-type spin polarization due to the local dipole field. Taking the sublattice interaction into account, The spin texture of the two sublattices around the corner of Brillouin zone still present remarkable Rashba-type vortex with exactly opposite patterns to each other, while at the Gamma point the interaction between two sublattices tends to cancel the local spin polarization. Our finding provides a promising avenue to search material candidates with strong hidden spin polarization, and thus broadens the type of materials that can be used for novel spintronic applications.