Accidental persistent spin textures in the proustite mineral family

Abstract

Persistent spin textures (PSTs) in momentum space have the potential to enable spintronic devices which are currently limited by low spin lifetimes in nonmagnetic spin-orbit coupled materials. We perform a first-principles study on the proustite mineral family, Ag$_3$BQ$_3$} (B=As,\,Sb; Q=S,\,Se), and show these chalcogenides exhibit a non-symmetry protected PST, which we refer to as symmetry-assisted PSTs. Chemical substitution can be used to tune the PST quality and properties, e.g., spin lifetime, and we find that a Rashba anisotropy criterion correlates with the PST area and spin lifetime for two of the three proustites examined. Last, we show that a first-order effective SOC Hamiltonian, often used in two-dimensional systems, is insufficient to describe the PST state in all proustites, suggesting that higher order models are necessary to fully describe PSTs in bulk three-dimensional materials.