SMCO CR BILAYER FILMS FOR HIGH-DENSITY RECORDING MEDIA/

The magnetic properties of a SmCo layer on a Cr underlayer, which was prepared by various Ar gas pressure (P-Ar), were studied. A single lin e appeared in each X-ray diffraction diagram and its intensity became strong when P-Ar was decreased from 1.06 to 0.13 Pa. The microstructur e observed by using atomic force microscopy showed that the surface mo rphological structure of Cr underlayers depended on P-Ar and the surfa ce of the Cr underlayer became smoother as P-Ar was decreased, while t he surface and the grain of the SmCo layer on the Cr underlayer were i ndependent of P-Ar. The grain size of SmCo layers was as small as 30 n m with the surface roughness of about 1 nm. The coercivity, the square ness ratio, and the coercivity squareness ratio of the SmCo layer on t he Cr underlayer prepared at 0.13 Pa were 155 kA/m, 0.92 and 0.92, res pectively. Those values suggest that an easy axis of magnetization for the SmCo layer is in plane and the switching field distribution is ve ry small. Although the crystal structure of the SmCo layer has not bee n clarified yet, it was found that the magnetic properties of SmCo lay ers can be controlled by the crystal structure of the Cr underlayer an d SmCo/Cr bilayer films are promising materials for the ultrahigh dens ity recording media. (C) 1997 American Institute of Physics.