Topological Surface States with Persistent High Spin Polarization across the Dirac Point in Bi2Te2Se and Bi2Se2Te

Helical spin textures with marked spin polarizations of topological surface states have been unveiled for the first time by state-of-the-art spin-and angle-resolved photoemission spectroscopy for two promising topological insulators, Bi2Te2Se and Bi2Se2Te. Their highly spin-polarized natures are found to be persistent across the Dirac point in both compounds. This novel finding paves a pathway to extending the utilization of topological surface states of these compounds for future spintronic applications.