Magnetic and conversion electron Moessbauer spectral study of amorphous thin films of Dy{sub x}Fe
Amorphous thin films of Dy{sub x}Fe{sub 100-x} and Dy{sub 20}Fe{sub 80-y}Co{sub y}, with various x and y values and of {approx}40 nm thickness, have been prepared by sputtering on polyimide films. Their magnetization curves and the Moessbauer spectra indicate that at 295 K the iron moments are preferentially oriented parallel to the film in Dy{sub 2}Fe{sub 98} and that Dy{sub 6}Fe{sub 94} is paramagnetic. The Dy{sub x}Fe{sub 100-x} thin films, where x is 17, 20, 24, 29, 32, 35, and 37, show perpendicular magnetic anisotropies and moderate coercive fields of at most 150 kA/m, whereas the Dy{sub 20}Fe{sub 80-y}Co{sub y} thin films, where y is 8, 13, 16, and 20, thin films show stronger perpendicular anisotropies and larger coercive fields of {approx}400 kA/m. The introduction of cobalt into the amorphous thin films increases their coercive field and the perpendicular magnetic anisotropy. The Moessbauer spectra of the Dy{sub x}Fe{sub 100-x} and Dy{sub 20}Fe{sub 80-y}Co{sub y} amorphous thin films consist of broadened sextets which have been analyzed with a distribution of hyperfine fields by assuming that the iron moments are oriented perpendicular to the plane of the film. Detailed fits of the Moessbauer spectrum of Dy{sub 20}Fe{sub 80} indicate that the cone angle of the iron magnetic moments cannot be determined with accuracy. The average hyperfine fields in the Dy{sub x}Fe{sub 100-x} amorphous thin films are smaller than those in the crystalline dysprosium--iron intermetallic compounds. The average hyperfine field increases from {approx}140 kOe in the Dy{sub x}Fe{sub 100-x} films to {approx}220 kOe in the Dy{sub 20}Fe{sub 80-y}Co{sub y} films, an increase which is in agreement with the increase in the saturation magnetization. The x dependence of the isomer shift indicates that there is strong dysprosium--iron bonding, whereas the y dependence of the isomer shift reveals an enhancement of the d-electron localization. From earlier x-ray magnetic circular dichroism results and the Moessbauer spectral results presented herein, iron magnetic moments of 0.87 or 0.67{mu}{sub B}, corresponding to 2.9 or 2.8 holes in the iron 3d band, have been obtained for the Dy{sub x}Fe{sub 100-x} amorphous thin films with x greater or smaller than 27, respectively. {copyright} 2001 American Institute of Physics.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40230560
- Journal Information:
- Journal of Applied Physics, Vol. 90, Issue 4; Other Information: DOI: 10.1063/1.1385574; Othernumber: JAPIAU000090000004001934000001; 053116JAP; PBD: 15 Aug 2001; ISSN 0021-8979
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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