Volume 88, Issue 4, 15 August 2000
Index of content:
- MAGNETISM AND SUPERCONDUCTIVITY (PACS 74-76)
88(2000); http://dx.doi.org/10.1063/1.1305907View Description Hide Description
The anisotropy contributions in epitaxial Fe/MnPd bilayers were analyzed in this study. It was found that due to ferromagnetic–antiferromagnetic interfacial exchange coupling, large uniaxial and cubic anisotropy contributions are also induced, in addition to the unidirectional anisotropy. These contributions play an essential role in the magnetization reversal process of the system, in which unusual reversal processes were found upon some fields orientations.
88(2000); http://dx.doi.org/10.1063/1.1305833View Description Hide Description
The magnetic and structural properties of sputteredfilms were examined. CoFe films 300 Å thick deposited on Si substrates at room temperature showed large coercive fields of 140 Oe. When similar thickness films were deposited at 100 °C, the coercivity dropped to 90 Oe, and when they were deposited on CoO, the coercivity was reduced to 12 Oe. Cross-sectional imaging with transmission electron microscopy revealed that the CoO underlayer had induced a columnar grain structure in the CoFe, with grain diameters ranging from 50 to 150 Å. CoFe films grown on Si contained larger grains of 200–350 Å in diameter with fewer distinct vertical grain boundaries. Lorentz microscopy showed that domain walls in the hard CoFe film formed complex, fixed patterns in fields less than the coercivity, whereas walls in the CoFe/CoO sample were more conformal and mobile in response to changing fields. Possible structural origins for the wide variation in coercivity obtained with different substrates, deposition temperature, and thickness of CoFe films are discussed.
Microstructure evolution, magnetic domain structures, and magnetic properties of Co–C nanocomposite films prepared by pulsed-filtered vacuum arc deposition88(2000); http://dx.doi.org/10.1063/1.1305557View Description Hide Description
Co-based nanocrystals encapsulated in carbon have potential applications in ultra-high-density magnetic recording media. In this work, 65, and 70 at. %) nanocompositefilms were prepared by pulsed-filtered vacuum arc deposition. Subsequent thermal annealing was performed in vacuum at various temperatures. The films were characterized by non-Rutherford backscattering spectrometry, transmission electron microscopy, Raman spectroscopy, atomic-force microscopy, and magnetic-force microscopy. The as-deposited films were found to be amorphous. After annealing at appropriate temperatures, the films were found to be consisting of hexagonal close-packed nanocrystalline Co grains encapsulated in graphite-like carbon. Clear magnetic-force microscopy images were only observed in those filmsannealed at sufficiently high temperatures, indicating that there was perpendicular magnetic anisotropy in these films. The magnetic hysteresis loops of the films were measured by a superconducting quantum interference device magnetometer. The optimum annealing temperature for the maximum coercivity was found to depend on the cobalt concentration. For a sample about 20 nm thick after annealing at 350 °C in vacuum for 1 h, the saturation magnetization was 500 emu/cm3, the coercivity was 460 Oe, and the ratio of the remanence to the saturation magnetization was 0.68 at 300 K. Our results are consistent with those of the sputtered Co–C films recently reported in the literature.