Magnetic and recording properties of sputtered CoCrTa/Cr thin-film media

The magnetic and recording properties of CoCrTa/Cr, longitudinal, magnetic, recording media, with various Cr contents, were investigated by changing the deposition temperature, the Cr thickness and the CoCrTa thickness. The Cr content of the CoCrTa magnetic layer was varied from 10-14 at.% Cr and the films were deposited on textured NiP/AlMg substrates by direct-current (dc) magnetron sputtering. Both the circumferential magnetic coercivity (H sub c ) and the coercivity orientation ratio (Or) of the media increased as the deposition temperature increased. The optimum Cr thickness was 50-70 nm; below this optimum value both H sub c and the Or were small, and above this value the Or decreased. As the CoCrTa thickness increased, the Or continuously decreased, while H sub c had a maximum of approx1600 Oe near the 40 nm thickness. The signal-to-noise ratio of the CoCrTa/Cr films increased as the deposition temperature, the Cr thickness and the CoCrTa thickness increased. However, the bit shift was lowest when the thicknesses of the CoCrTa and Cr layers were 50-60 nm and 50-70 nm, respectively. The CoCrTa magnetic films with 10 at.% Cr had the highest signal to noise ratio of 33 dB and the lowest bit shift of 9 ns. Our results showed that the Or factor is an important parameter for high-performance recording characteristics as is a high H sub c .