Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 43: Magnetization Dynamics III
MA 43.9: Vortrag
Donnerstag, 3. April 2014, 17:15–17:30, HSZ 401
Time-resolved imaging of isolated confined spin-wave packets — •Philipp Wessels1, Marek Wieland1, Jan-Niklas Tödt2, and Markus Drescher1 — 1Institute for Experimental Physics, University of Hamburg, Germany — 2Institute of Applied Physics, University of Hamburg, Germany
We present spatially and temporally resolved measurements on the dynamics of isolated spin-wave packets created by a short, broadband current pulse. The time evolution of the magnetization in confined magnetic media is analyzed by a time-resolved scanning Kerr microscope (TR-SKM) via the magneto-optic Kerr effect (MOKE) in combination with femtosecond laser pulses to carry out stroboscopic pump-probe experiments.
With a novel pump approach utilizing a magnesium photocathode as electro-optical switch, the generation of intense electronic current pulses becomes possible for excitation of magnetic systems with the transported transient magnetic field. The available master laser pulses of 1030 nm wavelength and 290 fs duration are doubled in frequency to obtain probe pulses of 515 nm wavelength which are further converted into UV pump pulses of 258 nm wavelength by another frequency doubling stage to drive the photocathode.
This enables jitter-free measurements on isolated spin-wave packets in permalloy (Ni80Fe20) microstructures with a temporal resolution < 10 ps and a spatial resolution < 670 nm FWHM. The spatially and temporally resolved data set permits a direct observation and global analysis of the dynamic parameters defining the wave-packet.