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MA: Magnetismus

MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)

MA 14.59: Poster

Dienstag, 25. März 2003, 15:15–19:15, Zelt

Inductive Measurement of Fast Magnetization Dynamics in Epitaxial Films — •Rainer Hartl, Stefan Ganzer, and Günther Bayreuther — Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93040 Regensburg

An inductive method for the measurement of dynamic processes in ferromagnetic films is described. A fast pulse generator is used to excite the magnetization of the sample located in the center of a coplanar waveguide with a central conductor 100 µm to 150 µm wide which also picks up the signal induced by the motion of the magnetization. A digital sampling oscilloscope with a bandwidth of 20 GHz is used for signal detection. To extract the dynamic magnetization response, a reference waveform is subtracted which was recorded with the magnetization pinned by a strong external field.

Besides 50 nm thick polycrystalline Permalloy films epitaxial Fe(001) and FeCo(001) films on GaAs(001) with a thickness of 1 to 15 nm were studied. After pulse excitation the free precession of the magnetization is observed with a characteristic damping constant. The precession frequencies are in the range of several GHz as expected. The strength of the superimposed uniaxial and fourfold anisotropies observed in the epitaxial films can be adjusted in a wide range by variation of composition and thickness. The precession frequency and damping coefficient as functions of thickness, anisotropies and orientation of pulse and bias field are compared with conventional FMR measurements.