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MA: Fachverband Magnetismus

MA 31: Magnetization Dynamics III

MA 31.2: Vortrag

Mittwoch, 16. März 2011, 11:15–11:30, HSZ 403

Time-resolved magnetization dynamics of tetragonally distorted antidot lattices — •Benjamin Lenk, Fabian Garbs, and Markus Münzenberg — I. Physikalisches Institut, Universität Göttingen

Femtosecond laser pulses can be used to optically excite (pump) and subsequently measure (probe) magnetization dynamics on timescales as long as nanoseconds. Two-dimensional arrays of antidots in a ferromagnetic film provide a periodic “potential” to the excited spin waves and induce drastic changes in the magnetization dynamics.

Magnonic modes with Bloch-like character can be observed as well as non-dispersive localized modes situated at the edges of the individual antidots. The understanding of these rivaling effects is only possible via the locally varying internal magnetic field. In the presented work a tetragonal distortion of the initially square lattice is used to address this issue. In combination with the applied external field the resulting asymmetry leads to differently large overlaps of the regions of strong field inhomogeneity.

We focus on the influence of the in-plane angle between external field and distorted antidot lattice. In particular, by applying the field along the long or short axis the overlap of regions of inhomogenious internal magnetic field can be varied. Thus, a tuning of the degree of localization is possible.