Regensburg 2004 – wissenschaftliches Programm

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MA: Magnetismus

MA 7: Magnetische Abbildungsverfahren

MA 7.1: Vortrag

Montag, 8. März 2004, 15:15–15:30, H22

Stroboscopic wide-field Kerr microscopy with ps time resolution — •Andreas Neudert, Jeffrey McCord, Rudolf Schäfer, and Ludwig Schultz — Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, P.O. Box 270016, D-01171 Dresden, Germany

We have extended a standard wide-field Kerr microscope with a pulsed solid-state laser as illumination source to investigate magnetization processes with a temporal resolution of about 30 ps. This is achieved by stroboscopic imaging, thus limiting the observation to repeatable processes. The repetition frequency of the laser pulses is 23 MHz, thus limiting the time frame of the observation to 43 ns. The spatial resolution is about 0.3 µm. Due to the good SNR ratio, integration times for the pictures are down to 50 ms/frame. The magnetic samples are excited by using standard pulse generators with rise-times down to 100 ps, which are directly triggered by the pulsed laser source. First results, demonstrating the capabilities of the experimental setup, on the vortex movement in structured Permalloy elements will be shown. A clearly different behavior of the motion of a vortex compared to quasistatic remagnetization processes is observed. The vortex structure first broadens and then restores some µm away in a new equilibrium state.

This work is funded by the DFG Schwerpunktprogramm 1133 "Ultrafast magnetization processesNo-dq.