Regensburg 2010 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 23: Micro- and Nanostructured Magnetic Materials III

MA 23.7: Vortrag

Donnerstag, 25. März 2010, 11:45–12:00, H3

Time-resolved magnetization dynamics of antidot square lattices in nickel — •Benjamin Lenk, Fabian Garbs, Henning Ulrichs, Andreas Mann, 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. We use pulses from a Ti:Sa mode-coupled laser system to investigate nickel films with thicknesses of several tens of nanometers and find (on continuous films) uniform precession as well as propagating dipole-dominated spin waves.

The creation of a periodic magnetic “potential”, namely arrays of micron-sized antidots, induces – in analogy to photonic crystals – drastic changes in the magnetization dynamics: Not only do some previously observed modes disappear, but moreover, additional modes can be excited whose frequency shows only minimal dependence on the applied field. We focus on the behaviour of these new modes and especially resolve the influence of the in-plane angle between external field and antidot lattice orientation. In particular, we verify the collective nature of the non-dispersive modes by experiments on single antidots.

Additionally, first results on magnonic wave guides – represented by a missing line of antidots – are shown. These provide an outlook to future applications in terms of spin wave logic devices.