Ferromagnetic resonance studies of Py bilayers for the system (Permalloy/Al2O3) (abstract)

We report a detailed ferromagnetic resonance study, performed at X band and room temperature, of magnetic permalloy (Py) bilayers (Py1/Al2O3/Py2) deposited by rf sputtering on mica substrates. We will present and discuss results relative to two series of Py bilayers characterized by an ultrathin Py layer thickness and corresponding to the two following sets of spacer thickness ts: (40;30;19 A) and (15;12;9 A). These films have been deposited at room temperature and subsequently annealed (at T=220 and 190 °C, respectively, for these two sets). The resonance spectrum is studied as a function of the orientation [ΘH=(N,H) with respect to the film normal N] of the applied dc field H in a plane perpendicular to the film. (i) For the three samples of the first series the resonance spectrum is composed of two resolved lines which can be attributed to the resonances of the individual layers (Py1 and Py2) dynamically uncoupled. As for a single Py layer, the angular variation Hres(ΘH) of each line observed is well a...