Detection of current induced spin polarization in epitaxial Bi_2Te_3 thin film

摘要

We electrically detect charge current induced spin polarization on the surface of a molecular beam epitaxy grown Bi_2Te_3 thin film in a two-terminal device with a ferromagnetic MgO/Fe contact and a nonmagnetic Ti/Au contact. The two-point resistance, measured in an applied magnetic field, shows a hysteresis tracking the magnetization of Fe. A theoretical estimate is obtained for the change in resistance on reversing the magnetization direction of Fe from coupled spin-charge transport equations based on the quantum kinetic theory. The order of magnitude and the sign of the hysteresis are consistent with the spin-polarized surface state of Bi_2Te_3