Berlin 2008 – scientific programme
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MA: Fachverband Magnetismus
MA 26: Spin Dynamics / Spin -Torque II
MA 26.13: Talk
Thursday, February 28, 2008, 17:45–18:00, EB 301
Ultrafast dynamics in optically excited nickel nanodiscs — •Georg Müller1, Gerrit Eilers1, Zhao Wang1, Malte Scherff1, Ran Ji2, Kornelius Nielsch2, and Markus Münzenberg1 — 1IV. Phys. Institute, Georg-August-University, Friedrich-Hund-Platz 1, D-37077 Göttingen — 2Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle
The temporal change in the Kerr angle of an in-plane magnetized nano patterned nickel wedge structure as the response to a fs laser pulse is investigated. The examined structure consists of an array of discs with a diameter of 185 nm and a separation of 280 nm, whose thickness is varied from 4 to 40 nm, and is prepared by optical interference lithography. The traced Kerr signal dynamics comprises a wealth of different modes which can be mostly attributed to reflectivity changes of the film due to the generation of surface acoustic waves or even magnetoelastic coupling. Nevertheless, one mode is clearly identified to be of pure magnetic origin. The theoretical mode spectrum of a single nanodisc obtained by micromagnetic simulations shows that the experimentally excited mode is of end mode type. A comparison between the theoretically and experimentally determined dependence of the frequency on the structure thickness allows to derive an approximate expression for the dipole interaction between the discs in the patterned film.
Research is supported by the DFG priority program 1133 'Ultrafast Magnetization Processes'.