Temperature Gradient Effects on Spin Torque in Double Barrier Magnetic Tunnel Junctions with a Non-magnetic Metal Spacer

Temperature gradient effects on spin torque (ST) are studied in MgO-based double-barrier magnetic tunnel junctions (DBMTJs) with a non-magnetic metal (NM) spacer. Using non-equilibrium Green’s function (NEGF) formalism, it is found that the thermal ST (TST) show oscillatory behavior with an increase of theNM spacer thickness. The results also show a magnitude enhancement of the TST in a DBMTJ compared with a single-barrier MTJ (SBMTJ). Such behavior is related to the existence of the quantum well states inside the NM spacer and resonant tunneling effect. Therefore, a faster magnetization switching is possible by TST in a DBMTJ without any bias voltage.