Observation and control of the weak topological insulator state in ZrTe5

Abstract A quantum spin Hall (QSH) insulator hosts topological states at the one-dimensional (1D) edge, along which backscattering by nonmagnetic impurities is strictly prohibited. Its 3D analogue, a weak (WTI), possesses similar quasi-1D confined side surfaces. The enhanced confinement could provide route for dissipationless current and better advantages applications relative to strong insulators (STIs). However, surface usually not cleavable thus hard observe. Here, we visualize of WTI candidate ZrTe 5 angle-resolved photoemission spectroscopy (ARPES): band with spin-momentum locking was revealed on surface. We further demonstrate that bulk gap controlled external strain, realizing more stable state or an ideal Dirac semimetal (DS) state. highly directional spin-current tunable in will excellent platform applications.