Electronic Structure of the Topological Insulator Bi2Se3 Using Angle-Resolved Photoemission Spectroscopy: Evidence for a Nearly Full Surface Spin Polarization

摘要

We performed high-resolution spin- and angle-resolved photoemissionspectroscopy studies of the electronic structure and the spin texture on thesurface of Bi$_2$Se$_3$, a model topological insulator. By tuning the photonenergy, we found that the topological surface state is well separated from thebulk states in the vicinity of $k_z=Z$ plane of the bulk Brillouin zone. Thespin-resolved measurements in that region indicate a very high degree of spinpolarization of the surface state, $\sim 0.75$, much higher than previouslyreported. Our results demonstrate that the topological surface state onBi$_2$Se$_3$ is highly spin polarized and that the dominant factors limitingthe polarization are mainly extrinsic.