Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 2: Spin-Dynamics / Spin-Torque I
MA 2.3: Vortrag
Montag, 23. März 2009, 11:30–11:45, HSZ 04
Ways to magnonic crystals: Studies with femtosecond pump-probe technique — •Benjamin Lenk, Jakob Walowski, Andreas Mann, Henning Ulrichs, Gerrit Eilers, and Markus Münzenberg — I. Physikalisches Institut, Universität Göttingen
The propagation of surface modes on thin Nickel films is investigated with all optical pump-probe experiments. Laser pulses with a duration of 60 fs from a Ti:Sa mode-coupled laser system are used for optical excitation (pump pulse) as well as observation of the subsequent magnetic relaxation taking place in the pico- and nanosecond regime (probe pulse). The time dependent magnetization curves M(t), are recorded using the time-resolved magneto-optical Kerr effect (TRMOKE) in different external fields 0 mT ≤ µ0H ≤ 150 mT.
The behaviour of the different precessional modes observed (exchange-dominated perpendicular standing spin waves, dipole-dominated surface modes, and uniform precession) changes when going from a continuous to a periodically structured surface. The different mode wave vectors can be numerically determined from ν(H). Structuring the thin films with matching periodicity induces drastic changes in the mode frequency observed, indicating the interaction of the periodic modification with the propagating modes excited with the laser pulse.
Research is supported by DFG Schwerpunkt SPP 1133: "Ultrafast magnetization processes".