Ferromagnetic resonance study on Fe-SiO2 granular films

Abstract

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 (fv) 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 fv near the percolation threshold (fp). In particular, it was found for the films with fv=0.42 that the spin wave resonance modes satisfy the relation Hres∝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 fv is just below fp.

Structural Changes in Nanoparticle Catalysts as Monitored by Their Magnetic Properties

“…However, for systems with an inhomogeneous magnetization, as expected for well-faceted nanocrystals with a large lattice mismatch at the particle-support interface, [14] the excitation of other spin states becomes possible. [15,16] The high-field resonance, whose position strongly depends on gas adsorption, can be attributed to a surface mode, which is very sensitive to changes in the boundary conditions at the surface of the particle. The intensity of this resonance decreases strongly if the orientation of the static magnetic field deviates from the perpendicular orientation with respect to the surface.…”

Surface Magnetic Anisotropy of Epitaxial La0.7Mn1.3O2.84Thin Films

“…In general, in this crystal structure there exist vacancies in both the cation and anion sublattices. Moreover, those studies showed that the defect chemistry can be described with a cluster model, where cation and anion vacancies may not only be randomly distributed but also form more complex defectsmesoscopic cluster-type inhomogeneities [6,26,27]. The surface chemical segregation phenomena were observed in rare-earth doped manganites [28][29][30][31].…”

Electron spin resonance properties of semiconductor/granular film heterostructures with cobalt nanoparticles in millimeter waveband

“…The same FMR linewidth broadening effect and a sharp increase in DH with a decreasing concentration of nanoparticles were noted in Refs. [27][28][29]. The explanation of the observed dependences of magnetic losses is based on the model of the spin-polarized relaxation (SPR) developed in Ref.…”