Selective Control of Surface Spin Current in Topological Pyrite OsX₂ (X= Se, Te) Crystals

The development of next-generation spin-based nanoelectronic devices requires effective control and detection of spin polarization. Recently topological materials have shown promising potential in this field due to their unique spin textures. Here we report the discovery of highly anisotropic surface spin textures in the (001) surfaces of topological pyrite OsX₂ (X = Se, Te) crystals using first principles calculations and Wannier tight-binding models. The surface spin textures of topologically nontrivial OsX₂ features a transition from in-plane to out-of-plane spin polarization in the momentum space and are protected by local crystalline symmetries. The energy screening of bulk bands leads to selective filtering of the magnitude and orientations of the surface spin polarization. These results provide new physical insights for manipulating spin degree of freedom in spin logic devices and could inspire new strategies of search nonmagnetic materials hosting exotic spin properties.