Spin-polarization limit in Bi2Te3 Dirac cone studied by angle- and spin-resolved photoemission experiments and ab initio calculations

The magnitude of electron spin polarization in topologically protected surface states is an important parameter with respect to spintronics applications. In order to analyze the warped spin texture in Bi2Te3 thin films, we combine angle- and spin-resolved photoemission experiments with theoretical ab initio calculations. We find an in-plane spin polarization of up to similar to 45% in the topologically protected Dirac cone states near the Fermi level. The Fermi surface of the Dirac cone state is warped and shows an out-of-plane spin polarization of similar to 15%. These findings are in quantitative agreement with dedicated simulations which find electron density of the Dirac cone delocalized over the first quintuple layer with spin reversal occurring in the surface atomic layer. DOI: 10.1103/PhysRevB.87.035127