Structural and magnetic properties of Fe-Al₂O₃films prepared by helicon plasma sputtering

Abstract

Fe-Al2O3 films have been prepared by on-off deposition of Fe with continuous Al2O3 deposition, and also subsequently irradiated by 400 keV Ar ions for controlling of the structural and magnetic properties of the films. CEM spectra of the as-deposited films show the decrease in the average hyperfine fields (Hhfs) with decreasing Fe/ Fe-Al2O3 volume ratio with keeping the Hhfs orientation parallel to the film plane. The decrease in Hhfs indicates the decrease of the Fe particle size and the in-plane orientation of Hhfs implies the non spherical shape of Fe particles in the film. On the other hand, 400 keV Ar ion irradiation induces the change from the superparamagnetic characteristics to the ferromagnetic one; the ferromagnetic peaks showing the random orientation of Hhfs appear and indicate the spherical growth of Fe particles in Al2O3 matrix.