Spin-Flip Scattering Effect on the Current-Induced Spin Torque in Ferromagnet-Insulator-Ferromagnet Tunnel Junctions

摘要

We have investigated the current-induced spin transfer torque of aferromagnet-insulator-ferromagnet tunnel junction by taking the spin-flipscatterings into account. It is found that the spin-flip scattering can inducean additional spin torque, enhancing the maximum of the spin torque and givingrise to an angular shift compared to the case when the spin-flip scatteringsare neglected. The effects of the molecular fields of the left and rightferromagnets on the spin torque are also studied. It is found that $\tau^{Rx}/I_{e}$ ($\tau ^{Rx}$ is the spin-transfer torque acting on the rightferromagnet and $I_{e}$ is the tunneling elcetrical current) does vary with themolecular fields. At two certain angles, $\tau ^{Rx}/I_{e}$ is independent ofthe molecular field of the right ferromagnet, resulting in two crossing pointsin the curve of $\tau ^{Rx}/I_{e}$ versus the relevant orientation fordifferent molecular fields.