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MA: Fachverband Magnetismus

MA 7: Spin-Dynamics/ Spin-Torque II

MA 7.12: Talk

Monday, March 23, 2009, 18:15–18:30, HSZ 04

Polarization selective switching of magnetic vortices with rotating currents — •Michael Martens¹, Thomas Kamionka¹, Markus Bolte¹, Benjamin Krüger², Kang Wei Chou³, Tolek Tyliszczak³, Michael Curcic⁴, Bartel Van Waeyenberge⁴, Hermann Stoll⁴, and Guido Meier¹ — ¹Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Germany — ²I. Institut für Theoretische Physik, Universität Hamburg, Germany — ³Advanced Light Source, LBNL, Berkeley, CA, USA — ⁴Max-Planck-Institut für Metallforschung, Stuttgart, Germany

Magnetic vortices in micron-sized disks and squares are interesting objects of research for understanding fundamental field- and current-induced magnetization dynamics and offer new concepts for data storage devices. The selective switching of the vortex-core polarization, i.e the out-of-plane component of the magnetization, by resonant excitation has been shown both theoretically [1] and experimentally [2]. Here we present our experiments on polarization reversal using rotating currents through a permalloy square. The frequency and power dependent excitation is measured systematically by means of time-resolved scanning transmission X-Ray microscopy (STXM). The phase of the gyration with respect to the exciting current yields information about the Oersted-field and the spin-torque driven contribution to the excitation. In addition we found experimental confirmation of halo-formation near the switching threshold.

[1] S. K. Kim et al., Appl. Phys. Lett. 92, 022509 (2008).

[2] M. Curcic et al., Phys. Rev. Lett. 101, 197204 (2008).