Spin-flip scattering effect on the current-induced spin torque in ferromagnet–insulator–ferromagnet tunnel junctions

Abstract

We have investigated the current-induced spin transfer torque of a ferromagnet–insulator–ferromagnet tunnel junction by taking the spin-flip scatterings into account. It is found that the spin-flip scattering can induce an additional spin torque, enhancing the maximum of the spin torque and giving rise to an angular shift compared to the case when the spin-flip scatterings are neglected. The effects of the molecular fields of the left and right ferromagnets on the spin torque are also studied. It is found that τ Rx / I e ( τ Rx is the spin-transfer torque acting on the right ferromagnet and I e is the tunneling electrical current) does vary with the molecular fields. At two certain angles, τ Rx / I e is independent of the molecular field of the right ferromagnet, resulting in two crossing points in the curve of τ Rx / I e versus the relevant orientation for different molecular fields.