FERROMAGNETIC-RESONANCE STUDY ON FE-SIO2 GRANULAR FILMS

Ferromagnetic resonance (FMR) measurement was performed at the frequency of 9.8 GHz and at the room temperature on a series of Fe-SiO2 granular films fabricated by the Ar+-beam sputtering technique. Our results indicated that when the iron volume fraction (f(nu)) of the films exceeds 0.28, the FMR spectra are superpositions of volume modes and surface modes. The analysis on the effective anisotropy field suggests that the intrinsic anisotropy (including the volume and interface one) becomes maximal when f(nu) near the percolation threshold (f(p)). In particular, it was found for the films with f(nu) = 0.42 that the spin wave resonance modes satisfy the relation H-res proportional to n with a separation field of about 174 Gs between the successive modes. Our study reveals that Fe particles are coupled by a yet unknown interparticle interaction when f(nu) is just below f(p). (C) 1995 American Institute of Physics.