Regensburg 2010 – scientific programme

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MA: Fachverband Magnetismus

MA 16: Micro- and Nanostructured Magnetic Materials II

MA 16.4: Talk

Wednesday, March 24, 2010, 11:00–11:15, H23

Spin-Wave Interference in Rolled-Up Permalloy Microtubes — •Felix Balhorn, Sebastian Mansfeld, Andreas Krohn, Simon Jeni, Jesco Topp, Wolfgang Hansen, Detlef Heitmann, and Stefan Mendach — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg

Strained semiconductor bilayers can be utilized in order to fabricate rolled-up mictrotubes [1, 2]. We have used these structures as templates to roll up permalloy films with multiple rotations to form Rolled-Up Permalloy Microtubes (RUPTs) [3]. Here, we investigate the spin-wave spectra of RUPTs in axial magnetization geometry by means of broadband microwave absorption spectroscopy. The RUPTs show up to four resonances which exist in the experimentally accessible field range. The resonances are attributed to constructively interfering Damon-Eshbach like spin waves propagating around the circumference of the tube. This interpretation is confirmed by fitting the experimental data according to an analytical model. The fit matches the experimental data almost perfectly if we express the dipolar coupling between the magnetic layers by an effective layer thickness and allow for an anisotropy field. This field considers demagnetization effects caused by the curved structure of a RUPT [3] and can be measured independently in hard axis configuration. We acknowledge financial support by the SFB668, GrK 1286, and the Cluster of Excellence Nanospintronics.

[1] V. Y. Prinz et al., Physica E 6, 828 (2000); [2] O. G. Schmidt, and K. Eberl, Nature 410, 168 (2001); [3] S. Mendach et al., Appl. Phys. Lett. 93, 262501 (2008)