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

TL;DR

This paper studies how spin-flip scattering influences the current-induced spin transfer torque in ferromagnet-insulator-ferromagnet tunnel junctions, revealing an increase in torque and angular shifts due to scattering effects.

Contribution

It introduces the consideration of spin-flip scattering effects on spin torque in tunnel junctions, showing how it enhances torque and causes angular shifts, which were previously neglected.

Findings

Spin-flip scattering induces additional spin torque.

Spin torque is enhanced by spin-flip scattering.

Angular shift occurs in the spin torque due to scattering.

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 $\tau ^{Rx}/I_{e}$ ($\tau ^{Rx}$ is the spin-transfer torque acting on the right ferromagnet and $I_{e}$ is the tunneling elcetrical current) does vary with the molecular fields. At two certain angles, $\tau ^{Rx}/I_{e}$ is independent of the molecular field of the right ferromagnet, resulting in two crossing points in the curve of $\tau ^{Rx}/I_{e}$ versus the relevant orientation for different molecular fields.