Observation of a Highly Spin Polarized Topological Surface State in GeBi${}_2$Te${}_4$

Abstract

Spin polarization of a topological surface state for GeBi${}_2$Te${}_4$, the newly discovered three-dimensional topological insulator, has been studied by means of the state of the art spin- and angle-resolved photoemission spectroscopy. It has been revealed that the disorder in the crystal has a minor effect on the surface state spin polarization and it exceeds 75% near the Dirac point in the bulk energy gap region ($\sim$180 meV). This new finding for GeBi${}_2$Te${}_4$ promises not only to realize a highly spin polarized surface isolated transport but to add new functionality to its thermoelectric and thermomagnetic properties.

5 pages, 4 figures