Regensburg 2007 – scientific programme

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MA: Fachverband Magnetismus

MA 19: Spin-Dynamics/Switching I

MA 19.12: Talk

Wednesday, March 28, 2007, 18:00–18:15, H23

X-ray imaging of current driven stochastic domain-wall motion — •Guido Meier¹, Markus Bolte¹, René Eiselt¹, Ulrich Merkt¹, Benjamin Krüger², Daniela Pfannkuche², Dong-Hyun Kim³, and Peter Fischer⁴ — ¹Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Jungiusstr. 11, 20355 Hamburg — ²I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstrasse 9, 20355 Hamburg — ³Department of Physics and Institute for Basic Science Research, Chungbuk National University, Cheongju 361-763, South Korea — ⁴Center for X-Ray Optics, LBNL, Berkeley, CA 94720, USA

Magnetic transmission x-ray microscopy is used to directly visualize the influence of a spin-polarized current on domain walls in curved permalloy wires. Pulses of nanosecond duration and high current density up to 1.0×10¹²A/m² are used to move and to deform the domain wall. The current pulse drives the wall either undisturbed, i.e., as a composite particle through the wire or causes structural changes of the magnetization. Repetitive pulse measurements reveal the stochastic nature of current induced domain-wall motion. From the experiments we estimate the ratio ξ/α = 0.96±0.02 between the degree of nonadiabaticity ξ and the Gilbert damping parameter α. This indicates the importance of the nonadiabatic contribution to current driven domain-wall motion. Supported by the DFG via SFB 668 and GK 1286 as well as by the U.S. DOE Contract No. DE-AC02-05-CH11231.