Discovery of highly spin-polarized conducting surface states in the strong spin-orbit coupling semiconductor SbSe
arXiv:1801.00929 · doi:10.1103/PhysRevB.97.235306
Abstract
Majority of the AB type chalcogenide systems with strong spin-orbit coupling, like BiSe, BiTe and SbTe etc., are topological insulators. One important exception is SbSe, where a topological non-trivial phase was argued to be possible under ambient conditions, but such a phase could be detected to exist only under pressure. In this Letter, we show that like BiSe, SbSe, displays generation of highly spin-polarized current under mesoscopic superconducting point contacts as measured by point contact Andreev reflection spectroscopy. In addition, we observe a large negative and anisotropic magnetoresistance in SbSe, when the field is rotated in the basal plane. However, unlike in BiSe, in case of SbSe a prominent quasiparticle interference (QPI) pattern around the defects could be obtained in STM conductance imaging. Thus, our experiments indicate that SbSe is a regular band insulator under ambient conditions, but due to it's high spin-orbit coupling, non-trivial spin-texture exists on the surface and the system could be on the verge of a topological insulator phase.
5 pages, 4 figures, supplemental material not included
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