Lattice strain in Co/Pd multilayers was evaluated by means of transmission electron microscopy. Diffraction measurements indicated that the fcc lattice of Pd is formed in the region where the co layer was thinner than 2 nm and the lattice was compressed along the in plane direction by 2~3 %. we calculated the effect of the magnetostriction of the CoPd alloy formed at the interface K^<me>_u on the perpendicular anisotropy and it was 4.58×106 erg/cm^3. It was comparable to the demagnetizing energy (4.54×106 erg/cm^3) and explained the perpendicular magnetization of the multilayers with thin Co layers. Contribution of the magnetostriction of the CoPd alloy K^<me>_s to the surface anisotropy K_s was 0.29 erg/cm^2 and was 58 %. of the whole K_s.

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We have prepared Au/Co multilayers by electron beam evaporation on glass substrates, and investigated their magnetic properties, polar Kerr rotation, and galvanomagnetic effects. When the Co layer thickness was less than 7Å , the easy magnetization axis was perpendicular to the film plane. The Kerr rotation decreased monotonically with increasing wavelengh from 400nm to 900nm without any peaks. we measured magnetoresistance in the film with perpendicular magnetization by applying magnetic field Perpendicular to the film plane. Two different mechanisms contributed to MR ; a scattering mechanism in the magnetic wall and the granular GMR.

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Thermal stability of Pt/Co multilayered films with various additional elements was studied by means of the bulk anneling. In the film added with B or Zn, the effective perpendicular anisotropy K_<eff> was enhanced before annealig, however, the K_<eff> decreased dramatically after annealing at 400℃ for 30min. On the other hand, in the films with Ti or Si, the change of K_<eff> was smaller than that with other elements, and even after the annealing, the films showed squareness=1. From the TEM observation, the addition of Ti was found to prevent the development of crystallites. The addition of Ti or Si seems to be effective to improve the thermal stability of Pt/Co films.

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The magnetic properties of NdGd/FeCo and PrGd/FeCo multilayers, which were prepared by rf magnetron sputtering, were investigated. Adjusting the constituent and the bilayer period of these multilayers. we can obtain films which have. both a large. Kerr rotation at short wavelength and a good square hysteresis loop. The films are thought to be one of the candidates for the magneto-optical (MO) recording media in future. The proper construction to satisfy the MO media is as follows. The content of Gd is about 65% in GdNd layer, that of Co about 10% in FeCo layer and the thickness ratio of RE to TM about 1 is proper construction to demanded the need above. The Kerr angles rotation of NdGd/FeCo and PrGd/FeCo at 400nm are about 30% larger than those of ThFeCo which is used in current MO disk systems.

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Ferrimagnetic Gd-Co / antiferromagnetic Co-Ni-O or Ni-O double-layered films are prepared. These films exhibit displaced hysteresis loop, therefore it is found that two layers are coupled through the exchange force. Interface wall energy σ_w is relatively small. When the Gd-Co layer has the easy axis perpendicular to the film plane. the dependence of σ_w on temperature shows a peak around the compensation temperature of the Gd-Co layer. Considering the simulation using the molecular field theory, that peak is due to the decrease of the perpendicular anisotropy of the Gd-Co layer at the interface and the change of the demagnetizing energy of the Gd-Co layer. The Neel temperatures of Co-Ni-O and Ni-O are 280K and 340K, respectively.

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Media noise and repeated writing and erasing characteristics were measured on quadrilayer. MnBi magneto-optical disks. The media noises due to reflectivity and polarization fluctuation are 20 dB higher than those of TbFeCo disks. Surface roughness of the substrates affects the noise level. We found that the carrier level decrease with the number of writing cycles is caused by decomposition of the MnBi low-temperature phase and by the change from the low-temperature phase to the high- temperature phase in the writing process. The reliability of the MnBi writing cycle can be improved by optimization of the disk's heat structure and recording conditions.

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The behavior and mechanism of magnetic rotation of exchange coupled domain in the super resolution magneto-optical thin films are discussed. The magnetic rotation of the exchange coupled domain occurs at the critical magnetic field. And the critical magnetic field varies with the domain size. These properties are caused by the existence of a interface magnetic wall and a bloch magnetic wall.

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