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 15.36: Poster

Dienstag, 27. März 2007, 15:00–19:00, Poster A

Impedance of ferromagnetic microrings up to 120 MHz — •Thomas Kamionka, Toru Matsuyama, Ulrich Merkt, and Guido Meier — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg (Germany)

The interaction between a spin-polarized current and the magnetization in a ferromagnetic micro- or nanostructure is of great interest. It will offer new opportunities to design magnetic memory and logic devices. We will analyze the resonant interaction between a spin-polarized current and a magnetic domain wall using a ferromagnetic microring. Using the shape anisotropy of the ring a domain wall can be prepared. This is proven by magnetic-force microscopy and by measuring the anisotropic magnetoresistance. In a magnetic field in the plane of the microring an alternating current forces a transverse domain wall to oscillate like a particle with finite mass [1]. At resonance the oscillation should effect a detectable increase of the ring impedance. At a critical external magnetic field the domain wall becomes unstable and the magnetization of the ring switches to the global vortex state. Concomitantly we detected a sharp increase of the anisotropic magnetoresistance. We varied the amplitude and the frequency of the current and found indications of current-assisted magnetization switching.

[1] E. Saitoh et al., Nature 432, 203 (2004).