Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 17: Spin Dynamics / Spin Torque II

MA 17.4: Vortrag

Mittwoch, 24. März 2010, 15:15–15:30, H10

Dynamics of domain walls in thin films with out-of-plane magnetization — •Benjamin Krüger¹, Imam Makhfudz², Oleg Tchernyshyov², and Daniela Pfannkuche¹ — ¹I. Institut für Theoretische Physik, Universität Hamburg — ²Department of Physics and Astronomy, Johns Hopkins University

The possibility that domain walls can be shifted by a spin-polarized current flowing through the wall or by magnetic fields is important for memory and spintronic devices. While for small wires the dynamics of the wall is well described by a model in which the wall moves as a quasi particle[1,2,3] this model has to fail for broader wires and magnetic films where the current or field may be inhomogeneous.

We investigate the dynamics of domain walls in a thin magnetic film with a strong easy-axis anisotropy that favors the out-of-plane direction. It is found that the dominance of the gyrotropic force over the viscous one makes the dynamics of Bloch walls rather unusual. By distorting the wall it is possible to excite waves that propagate with different speed in the two directions along the wall. From these results one finds that the star-shaped gyrational trajectory of a magnetic bubble in a magnetic disc[4] is a result of superposition of two waves with the same wavenumber and different frequencies running in opposite directions along the wall that surrounds the bubble.

[1] W. Döring Z. Naturforsch. 3a, 373 (1948)

[2] L. Thomas et al. Nature 443, 197 (2006)

[3] L. Bocklage et al. Phys. Rev. Lett. 103, 197204 (2009)

[4] C. Moutafis et al. Phys. Rev. B 79, 224429 (2009)