Ab initio description of magnetization dynamics in tunnel junctions: Influence of bias voltage and material parameters

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The goal of this proposal is to investigate the dynamic magnetic processes in magnetic tunnel junctions that are important for future spintronics applications like magnetic memories. For successful high density memory devices it is desirable to have an effective spin-transfer torque on one hand and a low magnetic damping on the other hand. The purpose of the project is to understand the fundamental mechanisms for damping and for spin-transfer torque, particularly their dependence on bias, materials, and geometry. The influence of electron-phonon and electron-magnon scattering on the bias dependence is a key aspect of the proposal. Another key aspect is performing these calculations for a variety of materials, including alloys and amorphous materials, which are used today and half-metallic systems, which are of interest for their potential for high magnetoresistance. The effect of the dynamics on the performance of these materials is less well understood than it is for single crystal transition metal ferromagnets. All of these investigations will be done using an ab initio approach. Some of them require methodological developments.