A comparison of the uniaxial anisotropy in sputtered Co–Re and Co–Cr perpendicular recording media

Abstract

The effect of the presence of an intermetallic compound on the microstructure, crystalline anisotropic orientation, and perpendicular magnetic hysteretic properties was investigated based on CoRe and CoCr alloys. The results suggest that a phase segregation causes the formation of an intermetallic compound, Co3Cr, in the Co-rich CoCr alloy film. Consequently, it leads to the growth of isolated columnar particles because of the fact that the alloy composition lies within the two-phase region in the phase diagram. For homogeneous CoRe and CoCr alloys at high temperature, the resultant microstructures in a deposited film show equiaxial particles characterized by a large grain diameter. Magnetic hysteretic measurement on the film having various microstructure shows that high coercivity and good perpendicular anisotropy in the CoCr film is primarily due to the formation of isolated columnar particles in addition to the c-axis preferred orientation. Films having good c-axis preferred orientation but not the isolated columnar structure can not give good hysteretic properties for perpendicular recording media application. Also it was concluded in this work that in an isolated columnar structure film, the extent of c-axis dispersion (i.e., the value of Δθ50) affects the sharpness of the knee, but the Hc of the perpendicular hysteresis loop is not affected significantly.