Spin transfer torque in F/F devices with non-identical half-metallic layers

Using half-metals (e.g., Heusler alloys) as ferromagnetic elements in spintronic devices sometimes leads to unexpected results. While using identical magnetic materials for both fixed and free layers already generate some interesting properties [1], it may be challenging to implement magnetization switching in such system experimentally because the boundary between materials is not well defined in their parallel state. Moreover, materials’ symmetry cancels the linear term in voltage dependence of the out-of-plane torque. In this study, we calculate electric and spin currents using a Stoner model description of half metals and find the out-of-plane torque and exchange energy of an F/F device. Voltage dependence of the out-of-plane torque is calculated as well. The lack of material’s symmetry generates additional anisotropy in this torque’s angular dependence.

[1] V. Shablenko, Ya. B. Bazaliy, APS March Meeting 2023, S56.00012: Spin-transfer torque for two half metals in direct contact