Electrical Detection of the Spin Polarization Dueto Charge Flow in the Surface State of the Topological Insulator Bi1.5Sb0.5Te1.7Se1.3.

We detected the spin polarizationdue to charge flow in the spinnondegenerate surface state of a three-dimensional topological insulatorby means of an all-electrical method. The charge current in the bulk-insulatingtopological insulator Bi1.5Sb0.5Te1.7Se1.3(BSTS) was injected/extracted through a ferromagneticelectrode made of Ni80Fe20, and an unusual current-direction-dependentmagnetoresistance gave evidence for the appearance of spin polarization,which leads to a spin-dependent resistance at the BSTS/Ni80Fe20interface. In contrast, our control experiment onBi2Se3gave null result. These observationsdemonstrate the importance of the Fermi-level control for the electricaldetection of the spin polarization in topological insulators. [ABSTRACT FROM AUTHOR]