MAGNETIC AND RECORDING PROPERTIES OF SPUTTERED COCRTA CR THIN-FILM MEDIA/

The magnetic and recording properties of CoCrTa/Cr, longitudinal, magn etic, recording media, with various Or contents, were investigated by changing the deposition temperature, the Or thickness and the CoCrTa t hickness. The Cr content of the CoCrTa magnetic layer was varied from 10 to 14 at % Or and the firms were deposited on textured NiP/AIMg sub strates by direct-current (d.c.) magnetron sputtering. Both the circum ferential magnetic coercivity (H-c) and the coercivity orientation rat io (Or) of the media increased as the deposition temperature increased . The optimum Or thickness was 50 similar to 70 nm; below this optimum value both H-c and the Or were small, and above this value the Or dec reased. As the CoCrTa thickness increased, the Or continuously decreas ed, while H-c had a maximum of about 1600 Oe near the 40 nm thickness. The signal-to-noise ratio of the CoCrTa/Cr films increased as the dep osition temperature, the Or thickness and the CoCrTa thickness increas ed. However, the bit shift was lowest when the thicknesses of the CoCr Ta and Or layers were 50 similar to 60 nm and 50 similar to 70 nm, res pectively. The CoCrTa magnetic films with 40 at % Or had the highest s ignal to noise ratio of 33 dB and the lowest bit shift of 9 ns. Our re sults showed that the Or factor is an important parameter for high-per formance recording characteristics as is a high H-c.