Spin-wave resonances in exchange-coupled Permalloy/garnet bilayers

Exchange coupling at the interface between a single-crystal garnet film with a perpendicular anisotropy and a Permalloy film with an in-plane anisotropy was investigated both experimentally and theoretically. Wide-band (2-20 GHz) ferromagnetic resonance measurements in parallel configuration reveal spectra with multiple resonance lines (up to four). These data were analyzed by means of a standing spin-wave model extended to account for in-plane/out-of-plane anisotropy bilayers and to include a finite value of the bilinear interfacial exchange coupling J. The field and frequency evolutions of the observed multiple resonance peaks were satisfactorily reproduced using the value J=0.18 +/- 0.05 erg/cm(2). (C) 2010 American Institute of Physics. [doi: 10.1063/1.3475646]