Tuning the Surface Spin Textures of Topological Materials

Spin manipulation is a big challenge for spintronic devices. Many interesting physical phenomena come from playing with spin polarizations with electric field, magnetic field and photons. Effective control over spin current is critical for using spintronics in information processing. Here we explore the surface spin textures of topological materials using first principles calculations and Wannier tight-binding models. We have observed a transition from in-plane to out-of-plane spin polarizations on the surface of a topologically nontrivial pyrite-type crystal OsX2 (X=Se, Te). The energy screening of bulk bands leads to selective filtering of the magnitude and orientations of the surface spin polarizations. We have further investigated fine tuning of surface spin textures by external factors. We expect these results could provide new insights of correlations between band topology and spin polarizations and assist the design of future spintronic devices.