Influence of substrates on magnetic property and crystalline orientation of CoCrTa/TiCr perpendicular magnetic recording medium

The influence of substrates on magnetic property and crystalline orientation of CoCrTa/TiCr perpendicular magnetic recording medium was investigated using a glass plate and a Si(1 0 0) single crystal. Magnetic measurements revealed that the film sputtered on a Si(1 0 0) substrate possessed a higher perpendicular coercive force than that on glass, where the pretreatment of the Si(1 0 0) substrate by aqueous HF solution effectively improved the magnetic properties. X-ray diffraction analysis of the films indicated that the crystallinity of the TiCr layer formed on the Si(1 0 0) substrate with the HF pretreatment was higher than that on the glass substrate. It was also found that CoCrTa and TiCr layers on the Si(1 0 0) substrate with the HF pretreatment had a narrower distribution of their c-axis orientation than those on glass substrate. The results of X-ray diffraction analysis were consistent with those of the TEM observation for cross-section bright- and dark-field images and the corresponding THEED patterns. These results suggest that the crystalline surface of the Si(1 0 0) substrate with HF pretreatment has the effect of inducing preferred orientation in the TiCr underlayer, which leads to a decrease in distribution of the c-axis orientation of Co grains in the CoCrTa layer, resulting in an increase in the perpendicular coercive force.