Dresden 2014 – scientific programme

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MA: Fachverband Magnetismus

MA 55: Poster II

MA 55.44: Poster

Friday, April 4, 2014, 10:30–13:30, P2

Magnetic Damping: Domain Wall Dynamics vs. Local Ferromagnetic Resonance — •Tobias Weindler, Hans Bauer, Robert Islinger, Benedikt Boehm, Jean-Yves Chauleau, and Christian Back — Department of Physics, Universität Regensburg, D-93040 Regensburg, Germany

The damping coefficient (α) is a crucial quantity for any magnetization dynamics study. It plays a major role especially in domain wall (DW) dynamics where DW displacement is directly related to relaxation effects. For DWs submitted to magnetic fields, the domain wall mobility in the steady state regime is inversely proportional to α whereas it is proportional in the steady precessional regime. For current-induced DW motion, the mobility in the steady state regime is proportional to the ratio between the non-adiabaticity and the relaxation. However significant discrepancies have been reported for values of α measured in extended magnetic layers by ferromagnetic resonance (FMR) and when is used as an adjustment parameter in micromagnetic simulation of DW motion in magnetic stripes. In our study, we experimentally address this issue by consistently assessing α in Ni80Fe20 (Permalloy) from two different approaches on the same nanostructure. On one hand we use time-resolved scanning Kerr microscopy (TRMOKE) to perform local FMR on single Ni80Fe20 nanostripes. On the other hand, in the same nanostripes, domain walls are injected and field-driven displacements are evidenced and analysed by wide-field Kerr microscopy.