Dresden 2006 – scientific programme
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MA: Magnetismus
MA 27: Spin-Dynamics, Magnetization Reversal II
MA 27.7: Talk
Thursday, March 30, 2006, 11:45–12:00, HSZ 403
Magnetization Dynamics of the Ferrimagnet CoGd near the compensation point — •Michael Binder1, Alexander Weber1, Ingo Neudecker1, Georg Woltersdorf1, Oleksandr Mosendz2, Jan-U. Thiele3, Michael R. Scheinfein2, and Christian H. Back1 — 1Universität Regensburg, Universitätsstr. 31, 93040 Regensburg — 2Simon Fraser University, 8888 University Drive, V5A 1S6 Burnaby BC, Canada — 3San Jose Research Center, Hitachi Global Storage Technologies, 650 Harry Road, San Jose, CA 95120
Transition metal (TM)- Rare Earth (RE) - ferrimagnets are interesting systems to study magnetization dynamics. When the antiferromagnetic coupling between the two sublattices is strong, as it is the case for CoGd, there exist two transition temperature points, the compensation temperature Tcomp, where MGd=−MCo, and the angular momentum compensation temperature TL, where (M/γ)Gd=(M/γ)Co. These temperatures are sensitive to the concentration. For CoGd the room temperature concentration is about 78% Co. According to a simple mean field model for the coupled sub-lattices, the effective damping parameter αeff and the effective frequency ω increase quickly at TL. This total response can be measured using ferromagnetic resonance methods (FMR). However, one can also use laser pump/probe experiments which couple predominantly to the TM lattice. We present measurements on various samples. TR-MOKE and FMR were used to address the Co-subsystem and the whole ferromagnetic system. In FMR we find the expected increase of αeff and ω at the compensation point, while TR-MOKE measurements seem to indicate that the rate of energy loss remains nearly constant.