Regensburg 2004 – wissenschaftliches Programm
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MA: Magnetismus
MA 13: Poster:Schichten(1-23),Spinabh.Trsp(24-41),Exch.Bias(42-56),Spindyn.(57-67),Mikromag.(68-76),Partikel(77-90),Spinelektr.(91-97),Elektr.Theo.(98-99),Mikromag+PhasÜ+Aniso.(100-105),Magn.Mat.(106-118),Messmethod.(119-121),Obflm.+Abbverf.(122-123)
MA 13.65: Poster
Dienstag, 9. März 2004, 15:00–19:00, Bereich A
Dynamic time scales in all optical pump probe experiments — •M. Djordjevic1, M. Lüttich1, P. Moschkau1, P. Guderian1, T. Kampfrath1, R.G. Ulbrich1, B. Sass2, F. Leuenberger2, W. Felsch2, T.H. Kim3, J.S. Moodera3, and M. Münzenberg1 — 1IV. Phys. Inst., Universität Göttingen — 2I. Phys. Inst., Universität Göttingen — 3Francis Bitter Magnet Laboratory, MIT, USA
Ultrafast and coherent optical control of magnetization in ferromagnetic materials in the sub ns regime is a special field of interest for developing spintronics. Magnetization dynamics upon laser heating is investigated (Ti: Sapphire laser with 50fs duration of the pulse). Time resolved magneto optical Kerr effect with double modulation technique is used to simultaneously measure reflectivity, Kerr rotation and ellipticity of ferromagnetic and non-magnetic thin films (Fe, Ni, Co, Al, Cu). Optical artefacts lead to a non-magnetic contribution to the magnetic signal but they can be controlled, for example, by a two colour probe experiment. The mechanisms involved in ultrafast demagnetization can be described with the three temperature model by relating electron and spin temperature in the ps regime. In the domain of longer time scales >100ps, standing spin waves and shock waves are observed. From the precession dynamics the intrinsic Gilbert damping parameter and the Eigen frequency of the magnetic precessional states can be determined.