  Helical spin textures with the marked spin polarizations of topological
surface states have been firstly unveiled by the state-of-the-art spin- and
angle-resolved photoemission spectroscopy for two promising topological
insulators Bi$_2$Te$_2$Se and Bi$_2$Se$_2$Te. The highly spin-polarized natures
are found to be persistent across the Dirac point in both compounds. This novel
finding paves a pathway to extending their utilization of topological surface
state for future spintronic applications.
