Spin-orbit coupling and spin-momentum locking in proustite

Nonmagnetic materials with unidirectional spin-momentum locking, or persistent spin texture (PST), have been shown to exhibit electronic spin transport properties conducive to spintronics applications. Most reported PSTs in bulk materials are observed near high symmetry time-reversal invariant momenta (TRIMs) and are protected by the present symmetries - these PSTs are known as symmetry-protected PSTs (Tao and Tsymbal 2018). In this talk, we will show the presence of a bulk PST in Ag₃AsS₃ which is not strictly symmetry-protected and discuss the characteristics of the spin-orbit coupling (SOC) which allow PSTs to exist near low symmetry TRIMs. We will show how chemical substitutions influence the band dispersion and SOC and discuss the implications for the material’s PST. Our work provides improved understanding of PSTs and how they may be designed in complex dielectrics without requiring particular crystallographic symmetries.

Tao, L. L., and Evgeny Y. Tsymbal. 2018. “Persistent Spin Texture Enforced by Symmetry.” Nature Communications 9 (1): 2763.