Spin Wave Resonances in GaMnAs

Ferromagnetic resonance (FMR) measurements were carried out on a series of GaMnAs thin films with different thicknesses grown by low temperature molecular beam epitaxy. Clear spin wave resonances were observed in addition to FMR when the applied magnetic field was perpendicular to the film plane. The spin wave spectra show a nearly linear dependence of the resonance mode positions on the mode number, suggesting that the magnetization profile of the GaMnAs films is not uniform in the growth direction. A first-order analysis of these effects is presented along with the experimental data.