Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 22: Spin Dynamics / Spin Torque III

MA 22.7: Vortrag

Donnerstag, 25. März 2010, 11:15–11:30, H10

Non-adiabatic spin transfer torque investigated using thermally activated magnetic domain walls in permalloy wires — •Matthias Eltschka¹, Mathias Wötzel^1,2, Takeshi Kasama², Jan Rhensius^1,3, Stephen Krzyk¹, Laura Heyderman³, Rafal Dunin-Borkowski², Ulrich Nowak¹, and Mathias Kläui¹ — ¹Fachbereich Physik, Universität Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany — ²Center for Electron Nanoscopy, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark — ³Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland

The understanding of the interplay between spin-polarized currents and magnetization as well as the determination of the spin torque terms are of scientific interest and essential for many proposed applications.

Using transmission electron microscopy we investigate thermally activated domain walls (DWs) jumping back and forth between two pinning sites in permalloy wires at room temperature. The motion is of pure thermal origin without the influence of external magnetic fields or electron currents. Considering the DW as a quasi particle in a local potential with two metastable states we show that this DW movement can be described by an Arrhenius law. Subsequently, we investigate the change of the local potential by constant currents which are far below the threshold values needed for DW propagation and do not induce significant heating. Based on a 1D description of the spin transfer torque effect and the Arrhenius law we derive the non-adiabatic coefficient β for a transverse and a vortex DW.