  It is recently noted that in certain centrosymmetric compounds, spin-orbit
interaction couples each local sector that lacks inversion symmetry and thus
leads to visible spin polarization effects in the real space, dubbed as 'hidden
spin polarization (HSP)'. However, observable spin polarization of a given
local sector suffers interference by its inversion partner, impeding material
realization and potential applications of HSP. Starting from a single-orbital
tight-binding model, we propose a nontrivial way to protect strong
sector-projected spin texture through minimizing the interaction between
inversion partners by nonsymmorphic symmetry. The HSP effect is generally
compensated by inversion partners near the {\Gamma} point but immune from
interaction around the boundary of the Brillouin zone. We further summarize 17
layer groups that support such symmetry-assisted HSP and identify by
first-principle calculations hundreds of quasi-2D materials from the existing
databases, among which a group of rare-earth compounds LnOI (Ln = Pr, Nd, Ho,
Tm and Lu) serves as great candidates showing strong Rashba- and
Dresselhaus-type HSP. Our finding also provides an ideal platform to control
HSP for emergent physical effects, such as opening a hybridization gap by
tensile strain to realize the time-reversal-invariant topological
superconductivity.
