Spin–momentum locking induced non-local voltage in topological insulator nanowire

Abstract

The momentum and spin of charge carriers in the topological insulators are constrained to be perpendicular to each other due to the strong spin–orbit coupling. We have investigated this unique spin–momentum locking property in Sb₂Te₃ topological insulator nanowires by injecting spin-polarized electrons through magnetic tunnel junction electrodes. Non-local voltage measurements exhibit an asymmetry with respect to the magnetic field applied perpendicular to the nanowire channel, which is remarkably different from that of a non-local measurement in a channel that lacks spin–momentum locking. In stark contrast to conventional non-local spin valves, simultaneous reversal of magnetic moments of all magnetic contacts to the Sb₂Te₃ nanowire alters the non-local voltage. This unusual asymmetry is a clear signature of the spin–momentum locking in the Sb₂Te₃ nanowire surface states.