Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 15: Poster:ThinFilms(1-33),Transp.(34-49),ExchBias(50-56),
Spindynamics(57-70),Micro-nanostr.Mat.(71-82),
Particles/Clust.(83-88), Mag.Imag./Surface(89-96),
Spinelectronics(97-109), Theory/Micromag.(110-116),
Spinstruct/Phasetr.(117-128),Magn.Mat.(129-139),
Aniso.+Measuring(140-145), MolMag.(146-152),
MSMA(153-156)
MA 15.62: Poster
Dienstag, 27. März 2007, 15:00–19:00, Poster A
Nonlinear spin dynamics and microwave assisted switching in nanostructured rings — •Jan Podbielski1, Kristina Reckwell1, and Dirk Grundler2 — 1Institut für Angewandte Physik und Zentrum für Mikrostukturforschung, Universität Hamburg, Jungiusstr. 11, D-20355 Hamburg — 2Physik Department E10, Fakultät für Physik, Technische Universität München, James-Franck-Str. 1, D-85748 Garching
We report a method to induce large angle spin precession in nanostructured ferromagnets. For this we have fabricated coplanar wave guides (CPWs) with a width of only 3 µm. We have patterned mesoscopic Permalloy rings with an outer diameter of 2 µm directly on top of such CPWs. Using a broadband network analyzer we generate a microwave magnetic field to induce large angle spin precession phenomena. We observe shifts of the ring’s spin wave eigenfrequencies as a function of microwave magnetic field amplitude. In particular we find both shifts to higher and to lower frequency. The behavior depends on the ring segment where the spin wave eigenmode is localized. Increasing the microwave power further leads to irreversible jumps in the spin wave spectrum. We attribute this to microwave assisted switching. The dynamically induced switching reveals a resonant behavior, i.e. the efficiency for switching depends on not only the amplitude but also the frequency of the irradiated microwave. We will discuss possible microscopic mechanisms for these intriguing observations. The work is supported by the DFG via SFB668 and via the excellence cluster "Nanosystems Initiative Munich (NIM)".