Title :
Magnetic properties of amorphous films of Bi2O3 -Fe2O3-CaO
Author :
Rao, B.U.M. ; Srinivasan, G.
Author_Institution :
Dept. of Phys., Oakland Univ., Rochester, MI, USA
fDate :
9/1/1992 12:00:00 AM
Abstract :
The magnetic properties of amorphous films with the composition (Bi2O3)0.5-x(Fe2O3 )0.5(CaO)x are investigated. Samples with x=0-0.05 were prepared in a pure oxygen or mixed oxygen-argon atmosphere by the RF sputtering technique. As-sputtered films are X-ray amorphous and paramagnetic at room temperature. The films show a spontaneous magnetic moment when annealed in air at temperatures T a above 400°C. Data on the room temperature saturation induction 4πM with Ta, followed by a maximum in 4πM for Ta=600-700°C, depending on the x-value. At higher Ta, a decrease in 4πM is observed. The room temperature 4πM is found to decrease with increase in x, from 970 G for x=0.1 to 300 G for x=0.5. The Curie temperature is lower than the crystallization temperature. Ferromagnetic resonance studies show a uniaxial or planar anisotropy in the films. X-ray diffraction data do not indicate the precipitation of crystalline ferrimagnetic oxides in the annealed films and the observed magnetization is therefore attributed to ordered amorphous clusters
Keywords :
Curie temperature; annealing; bismuth compounds; calcium compounds; ferrimagnetic properties of substances; ferrites; ferromagnetic resonance; magnetic anisotropy; magnetic moments; magnetic properties of amorphous substances; magnetic structure; magnetic thin films; magnetisation; paramagnetic properties of substances; sputtered coatings; 400 to 800 C; Bi2O3-Fe2O3-CaO; Curie temperature; FMR; RF sputtering; X-ray diffraction; amorphous films; annealed; crystallization temperature; ferrimagnetic behaviour; magnetic properties; magnetic structure; magnetic thin films; ordered amorphous clusters; paramagnetic behaviour; planar anisotropy; room temperature saturation induction; spontaneous magnetic moment; uniaxial anisotropy; Amorphous materials; Annealing; Atmosphere; Bismuth; Crystallization; Ferrimagnetic films; Iron; Magnetic films; Magnetic properties; Temperature;
Journal_Title :
Magnetics, IEEE Transactions on
