Multilayered Co/Pt, Co/Pd and Co/Au films exhibit large perpendicular magnetic anisotropy. They have attracted attention as new materials for next-generation high-density magneto-optical recording media, and are being studied for applications in other areas besides. The coercivities of as sputtered m ultilayered Co/Pt and Co/Pd films are small but increase to 2〜3 kOe with the annealing at 300℃ in air. In this paper, the structure and magnetic properties and effects of the annealing in air on the multilayered Co/Au sputtering films have been studied. The dual-source rf magnetron sputtering method was employed in fabricating the films, using Ar as the sputtering gas, The thicknesses of Co layer and Au layer of the Co/Au films were 8.4Å and 18.2Å, respectively, and the total thickness was 3000Å. The uniaxial magnetic anisotropy constant (Ku) and the coercivity/ (Hc) of the films as sputtered was 7.8×10^5 erg/cm^3 and 50 Oe, respectively. The values of Ku and Hc increased with the annealing temperature and Ku and Hc showed at 200℃ 2.6×10^6erg/cm^3 and 150 Oe, respectively. The low-angle X-ray peak and the satellite peak intensities increased alter the 200℃ annealing. At the higher temperature than 250℃, Ku decreased and showed the minus values, and the oxidation of Co layer, the disorderization of the multilayered structure, and the segregation of Au and Co_3O_4 occured. This results show that the multilayered structure of Co/Au films is less stable than those of Co/Pt and Co/Pd films.
In the overwrite recording of two different signals, the very interesting forewoman, re-recording dip, have been reported. The recording mechanism is, however, still not clear. In this paper, "Contact printing model" is introduced to explain the dip of the re-recording phenomena. The previously recorded signal (S-1) is transferred on the surface of the tape where the overwritten signal (S-2) makes the susceptibility high to transfer the S-1 magnetically with opposite phase. The output signal of S-1 will be offset by the transferred signal, and reproduced the zero output that supposed to be the re-recording dip. This model is proved by some experiments.
Overwrite recording is one of the most important technologies in magnetic recording. in overwrite recording, a very interesting phenomenon so called "Re-recorded phenomena" have been observed so far, but mechanism is still not clear. In this paper, in order to explain the re-recorded phenomena, we have introduced the contact printing model and calculated a re-recorded dip of erasure characteristics by calculated simulation. As a result, the dip of re-recorded phenomena are qualitatively explained.
The Landau- Lifshitz-Gilbert (LLG) equation is solved to investigate the switching fields and magnetization reversal mechanisms of cubic, elongated, or hexagonal platelet particles. Squareness scarcely changes until the particle size exceeds a critical value. Some time interval is necessary for the irreversal transition to occur in each case. The switching fields and the magnetization reversal mechanisms of the particles change with the material parameters (size, exchange stiffness constant, anisotropy constant).