Dresden 2014 – scientific programme

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MA: Fachverband Magnetismus

MA 37: Spin Torque and Spin Excitations I

MA 37.8: Talk

Thursday, April 3, 2014, 11:30–11:45, HSZ 401

Non-local spin transfer torque and its effect on domain wall motion — •Martin Stier and Michael Thorwart — I Institut für Theoretische Physik, Universität Hamburg, Jungiusstraße 9, 20355 Hamburg, Germany

Current induced domain wall (DW) motion is well described by the Landau-Lifshitz-Gilbert equation which includes spin transfer torques (STT). Standard procedures lead to essentially two parts of the STT (adiabatic, non-adiabatic) which are considered to be spatially constant even in the vicinity of the DW. We present a basically exact method to solve the continuity equation which results in a non-local STT. This STT now depends sensitively on several model parameters, most prominently on the DW width, but also on the exchange coupling and the non-adiabaticity parameter. Additionally we find a quite natural reflection of the relaxation length in the STT. While for broad DWs the standard expressions of the STT are recovered, they differ completely for steep DWs. Finally, we show how the non-local STT affects the DW velocity including the impossibility to move very steep DWs.