Dresden 2006 – scientific programme

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MA: Magnetismus

MA 33: Spin-Dynamics, Magnetization Reversal III

MA 33.1: Talk

Thursday, March 30, 2006, 15:15–15:30, HSZ 403

Current-induced microwave excitations of nanomagnets made of single-crystalline iron — •Ronald Lehndorff, Henning Dassow, Reinert Schreiber, Daniel E. Bürgler, and Claus M. Schneider — Institut für Festkörperforschung, Foschungszentrum Jülich GmbH, D-52425 Jülich, Germany

The magnetization dynamics of nanomagnets under the influence of a spin-polarized current is of great interest since Slonczewski and Berger predicted the possibilities of magnetization switching and steady precessions in 1996 [1, 2].

We study the magnetization dynamics of nanomagnets made of epitaxial Fe with diameters of 100 nm to 200 nm and thicknesses of 2 nm relative to an extended Fe layer of 10 nm thickness that is magnetically hardened by interlayer exchange coupling over Cr to a 14 nm Fe layer.

We measure magnetoresistance and resistance versus current to characterize our samples. The switching behavior shows clear four-fold in-plane crystalline anisotropy of the Fe layers. Varying the field direction relative to the crystalline axes can assist the current-induced switching process.

We detect microwave signals due to steady large angle precessions of the magnetization and study the dependence on current, magnetic field and field angle relative to the crystalline axes.

[1] J.C. Slonczewski, J. Magn. Magn. Mater. 159, L1 (1996)

[2] L. Berger, Phys. Rev. B 54, 9353 (1996)