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MA: Fachverband Magnetismus

MA 43: Magnetization / Demagnetization Dynamics III

MA 43.3: Vortrag

Donnerstag, 19. März 2015, 10:00–10:15, EB 301

Spin-transfer Torque Magnetisation Switching in Multi-layered System from Atomistic Spin Dynamics — •Fan Pan¹, Anders Bergman², and Lars Bergqvist¹ — ¹Department of Material and Nano Physics, School of ICT, KTH Royal Institute of Technology, Electrum 229, 164 40, Kista, Sweden — ²Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20, Uppsala, Sweden

The magnetization dynamics of a synthetic layered magnetic materials, prototype for a magnetic random access memory device, has been investigated through first-principles and atomistic spin dynamics simulations (ASD). It is found that the magnetization dynamics driven by the spin-transfer torque (STT) is of nonlinear character and the roles of adiabatic and non-adiabatic STT are still not clear. Therefore, our study aims to gather a deeper understanding of these intrinsic properties. We have compared two different system geometries, both with an applied current flowing perpendicular to the plane of the layers. If no restriction is imposed to the magnetisation of the both outer layers, a steady-state processing motion is found. A more complicated switching behaviour is found if the magnetization of one layer is fixed and the other is free to rotate. In the latter case, the critical current density of the magnetization reversal is described both analytically and numerically. In addition, the optimal conditions of STT induced switching are suggested. Finally, we have performed calculations of experimental available systems using material parameters from electronic structure calculations based on density functional theory.