Dresden 2006 – wissenschaftliches Programm
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MA: Magnetismus
MA 33: Spin-Dynamics, Magnetization Reversal III
MA 33.9: Vortrag
Donnerstag, 30. März 2006, 17:15–17:30, HSZ 403
Intrinsic and non-local Gilbert Damping parameter in all optical pump-probe experiments — •Marija Djordjevic1, J. Walowski1, G. Eilers1, M. Münzenberg1, and J.S. Moodera2 — 1IV. Physikalisches Institut, Universität Göttingen — 2Francis Bitter Magnet Laboratory, MIT, Cambridge, USA
With the time resolution inherent using femtosecond laser pulses in all optical pump-probe experiments, the basic time constants of magnetic precessional modes, as well as the energy dissipation processes determining the Gilbert damping, can be studied. Our focus is to explore the underlying damping mechanisms and how they can be controlled. The non-local Gilbert damping due to evanescent spin currents can be studied at double layers (FM/NM), in which the thickness of the FM layer is varied. The precession moment emits a dynamic spin current that is subsequently damped in a material with a strong spin-orbit coupling. An enhancement in the Gilbert damping parameter for Ni/Pd and Ni/Cr double layers which is inversely proportional to the thickness of the Ni layer is observed. The frequency dependence of damping parameter for Ni/Cr films monitors presence of two-magnon scattering processes. The non-local damping for different Ni/NM double layers is found not to simply scale with the spin-orbit coupling constant. Increased roughness as well as the (non)compatibility of the DOS at EF of Ni and NM, have to be included to model the damping. It will be of special interest to connect the elementary relaxation mechanisms to the origin of non-local Gilbert damping, as it is seen on the LLG timescale.