Magnetic stability and noise characteristics of high Hc CoSm/Cr thin films

The effects of exposure time, annealing temperature and mechanical stress on the magnetic stability of CoSm/Cr thin films, as well as its noise characteristics, were studied. The coercivity (He) of the films decreases with time because the Sm is oxidized. This change is reduced by means of a protective over coat. With an annealing temperature increase, the Hc of Cr/CoSm/Cr film decreases. From Extended X-ray Absorption Fine Structure (EXAFS) analysis, it has been shown that the proportion of the Co/sub 5/Sm phase increases after annealing at 250/spl deg/C. Also, the Hc of the films increases with increasing compressive strain. The value of the change is about 3 times the value reported for CoPt. A low noise level and a high S/N at 97 kfci is obtained by weak exchange coupling caused by the increase in Ar gas pressure during Cr sputtering.