Berlin 2005 – scientific programme
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MA: Magnetismus
MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65
MA 20.54: Poster
Monday, March 7, 2005, 14:00–18:00, Poster TU C
All-optical probe of magnetization dynamics in exchange bias systems — •M. C. Weber1, H. Nembach1, H. Schultheiss1, C. Bayer1, S. Blomeier1, R. Kaltofen2, J. Schumann2, M. J. Carey3, B. Hillebrands1, and J. Fassbender4 — 1Fachbereich Physik, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany — 2Institut für Dünnschichtsysteme der Mikroelektronik, IFW Dresden, 01171 Dresden, Germany — 3Hitachi Global Storage Technologies, San Jose Research Center, San Jose CA 95120, USA — 4Institut für Ionenstrahlphysik und Materialforschung, FZ Rossendorf, 01314 Dresden, Germany
The picosecond optical control of the exchange bias anisotropy was investigated in real time for different exchange bias bilayers (NiFe/FeMn, CoFe/NiMn, CoFe/IrMn) using time-resolved magneto-optics. Upon photoexcitation the spin temperature is increased leading to a collapse of the interfacial exchange coupling. Both the shift fields and the easy axis coercivities are reduced within the first 10 ps. The unpinning is followed by a slower spin-lattice relaxation process. The deduced relaxation times turn out to be quite comparable (< 205 ps) for all bilayers. The thermal decoupling of the bilayers can lead to a high frequency precession of the magnetization of the ferromagnetic layers. The precessional response of the CoFe/IrMn system reveals a Kittel type field dependence of the precession frequency. Brillouin light scattering measurements of the field dependence of the FMR frequency are in good agreement with the real time measurements, further supporting the homogeneous mode character of the optically excited precession.