Thickness dependence of magnetic properties in (Fe) 0.73(Sm 2O 3) 0.27 nano-granular films

Abstract

(Fe) 0.73(Sm 2O 3) 0.27 nano-granular films with thicknesses varying from 46 nm to 220 nm were fabricated by a RF magnetron sputtering method. The static and dynamic magnetic properties of these films on thickness dependence have been investigated in detail. High-resolution transmission electron micrograph shows that the films consist of Fe granules and crystalline Sm 2O 3 matrix. The results reveal that there is a critical thickness t c around 65 nm in the (Fe) 0.73(Sm 2O 3) 0.27 nano-granular films. Below t c, the films possess an in-plane uniaxial anisotropy and lower H c. Above t c, the films exhibit a small perpendicular anisotropy, higher H c and stripe domains, and the stripe period increases with increasing film thickness. The dynamic permeability spectra measured over the frequency range of 0.1–7 GHz display one resonance peak for all thicknesses. The spectrum of the film with thickness below t c can be ascribed to the uniform coherent spin procession. Above t c, the increasing film thickness leads to an monotonously increase of the permeability (imaginary part), and a shift of resonance frequency towards the low frequency and a decrease of resonance linewidth for the films with thickness larger than 120 nm.