DETERMINATION OF THE FERRIMAGNETIC PRECESSION CONE OF INPLANE MAGNETIZED GARNET-FILMS USING OPTICAL MODULATION TECHNIQUE

Magnetic garnet films of composition (A, Bi)(3)(Fe, B)(5) O-12 are gro wn by liquid phase epitaxy on [111] oriented substrates of Gd-3 Ga-5 O -12, where A=yttrium or lutetium and B=aluminum or gallium. The ferrim agnetic resonance (FMR) of in-plane magnetized films is studied by ana lyzing the modulation of light, which passes the film parallel to the film normal. Modulation efficiencies up to 1.8% at 2.9 GHz are observe d at a wavelength of 0.633 mu m. From the measured modulation intensit ies the precession angles of the FMR are derived. The dependence of th e precession cone on the excitation frequency or on the external induc tion shows a foldover effect which, however, is smaller than for the F MR of perpendicularly magnetized films. Maximum precession angles up t o 14 degrees are achieved and the experiments indicate that saturation occurs. Light modulation is also observed at the first harmonic frequ ency, but the intensity is about 300 times weaker than at the fundamen tal frequency. (C) 1996 American Institute of Physics.