Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 8: Spindynamik I

MA 8.3: Vortrag

Freitag, 4. März 2005, 15:45–16:00, TU H1028

Magnetization dynamics in all optical pump probe experiments — •Marija Djordjevic, Mario Lüttich, Peter Moschkau, and Markus Münzenberg — IV. Physikalisches Institut, Universität Göttingen

Developing spintronics demands new insight in magnetization dynamics in the sub ns regime. Short pulses of Ti: Sapphire laser (50fs) are used in time resolved magneto optical Kerr effect experiments to follow electron and spin dynamics of ferromagnetic and not-magnetic thin films (Fe, Ni, Co, Al, Cu) upon laser heating. Different timescales are observed: ultrafast demagnetization in the first ps after the absorption of the laser pulse and precession of the magnetization in the GHz regime. The mechanisms involved in ultrafast demagnetization can be described within the three temperature model, which relates temperatures of electrons, lattice and spins. From this model electron-phonon and spin-phonon coupling constants can be determined. Standing spin waves are observed for longer time scales, >100ps. The precessive dynamics is in good agreement with dynamic LLG calculations, therefore the intrinsic and non-local Gilbert damping parameter can be determined, as well as the Eigen frequency of magnetic precessional modes.