HIGH-RESOLUTION BRILLOUIN LIGHT-SCATTERING AND ANGLE-DEPENDENT 9.4-GHZ FERROMAGNETIC-RESONANCE IN MBE-GROWN FE CR/FE ON GAAS/

Exploiting the high sensitivity of a recently assembled Brillouin-ligh t-scattering (BLS) spectrometer, we investigate the magnetic excitatio ns with nonvanishing in-plane wave vector k in antiferromagnetically c oupled Fe/Cr/Fe (001), grown by molecular-beam epitaxy. The BLS spectr a reveal surprisingly rich structures not previously observed in this very sample. In addition, we use angle-dependent 9.4-GHz ferromagnetic resonance to probe the uniform (k=0) collective excitation, previousl y investigated at 35 GHz. The observation of the acoustic and optical modes by both techniques allowed the determination of an accurate set of material parameters from the fit of theoretical curves to all data. While the results do not invalidate earlier conclusions, we offer an updated model which provides an alternative explanation for the observ ed spectra without the assumption of an extra effective surface anisot ropy field.