Spin Transfer Torque in a Graphene Lateral Spin Valve Assisted by an External Magnetic Field

Abstract

Spin-based devices are widely discussed for post-complementary metal-oxide-semiconductor (CMOS) applications. A number of spin device ideas propose using spin current to carry information coherently through a spin channel and transfering it to an output magnet by spin transfer torque. Graphene is an ideal channel material in this context due to its long spin diffusion length, gate-tunable carrier density, and high carrier mobility. However, spin transfer torque has not been demonstrated in graphene or any other semiconductor material as of yet. Here, we report the first experimental measurement of spin transfer torque in graphene lateral nonlocal spin valve devices. Assisted by an external magnetic field, the magnetization reversal of the ferromagnetic receiving magnet is induced by pure spin diffusion currents from the input magnet. The magnetization switching is reversible between parallel and antiparallel configurations, depending on the polarity of the applied charged current. The presented results are an important step toward developing graphene-based spin logic and understanding spin-transfer torque in systems with tunneling barriers.