Dresden 2011 – scientific programme
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MA: Fachverband Magnetismus
MA 30: Magnetic Semiconductors I
MA 30.1: Talk
Wednesday, March 16, 2011, 11:00–11:15, HSZ 401
Coherent magnetization precession in ferromagnetic (Ga,Mn)As induced by picosecond acoustic pulses — •Michael Bombeck1, Alexey Scherbakov2, Alexey Salasyuk1,2, Dmitri Yakovlev1,2, Andrey Akimov2,3, Xinyu Liu4, Christian Brüggemann1, Victor Sapega2, Jacek Furdyna4, and Manfred Bayer1 — 1Experimentelle Physik 2, Technische Universität Dortmund, Dortmund, D-44227, Germany — 2Ioffe Physical Technical Institute of the Russian Academy of Sciences, 194021 St. Petersburg, Russia — 3School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom — 4Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
In this work we investigate the influence of picosecond strain pulses on the magnetic properties of a thin film of a ferromagnetic semiconductor. By a pump-probe technique we measure the transient magneto-optical Kerr effect in a 200nm Ga0.95Mn0.05As film. Pump pulses of an amplified Ti:Sa-laser, applied to a 100nm Al-film serving as a optoelastic transducer, generate a strain pulse in the studied structure. Kerr rotation of a linearly polarized probe beam reflects the time evolution of magnetization. The effect of the strain pulses on the magnetic domains of the (Ga,Mn)As film is mediated by the strain-induced changes of the magneto-crystalline anisotropy. We observe the tilt of the magnetization vector M on a picoseconds time scale caused by the strain pulse and followed by the coherent precession of M with a frequency of 10 GHz around its equilibrium orientation.