Improvement of anisotropy of perpendicular magnetic recording tape by Ta addition and Kr sputtering gas (abstract)

Abstract

A perpendicular magnetic recording tape requires a high magnetic anisotropy field Hk and a small distribution of the perpendicular magnetic anisotropy field σhk/Hk. It can be expected that by the extension of the interplane distance of (002) plane d(002) in Co-Cr, a perpendicular magnetic anisotropy energy will be increased and Hk becomes higher. It can be also expected that the σhk/Hk becomes smaller by the improvement of the crystallinity of Co-Cr film. Therefore, in order to achieve the above, the following experiments were attempted. At first, a small amount of Ta was added to Co-Cr. This, as a result, extended the d(002) of the Co-Cr from 2.033 to 2.046 Å. Consequently, Hk was increased from 4.4 to 5.1 kOe and σhk/Hk was reduced from 0.14 to 0.11. Second, as a sputtering gas, Kr gas was used instead of Ar gas. The use of Kr resulted in greater crystallinity in the film, increasing the peak intensity I(002) of x-ray diffraction of the Co-Cr-Ta from 2090 to 2500 cps. Consequently, σhk/Hk was reduced up to 0.07. Last, a recording and reproducing experiment with the Co-Cr-Ta tape was attempted with the use of a hilical-scan VTR machine. As a result, a reproduced output of 56 nVO-P (μm T m/s) was obtained at the recording wavelength of 0.33 μm. This figure is equivalent to the output at the recording wavelength of 0.66 μm of metal-powder tape.