Effect of Dual-Magnetic-Layer on Performance of CoCrPt-SiO$_{2}$ Perpendicular Media

CoCrPt-SiO
₂
perpendicular recording media have been investigated in order to increase media signal-to-noise ratio (SNR) by introducing a dual-magnetic-layer structure into the CoCrPt-SiO
₂
recording layer. The dual-magnetic-layer structure consists of low- and high-M
_s
granular layers. The magnetic properties and recording performances of two kinds of dual-magnetic-layer media, one with a low-M
_s
bottom layer and another with a low-M
_s
top layer, were measured. The coercivity of the low-M
_s
bottom medium is higher than that of the low-M
_s
top medium, although they have the same thermal stability (K
_u
V/k
_B
T). We showed that using the low-M
_s
bottom layer gives a higher SNR. That is to say, SNR was improved by 3 dB compared with that of the high-M
_s
single-magnetic-layer medium, and it was even higher than that of the low-M
_s
single-magnetic-layer medium. It is thus concluded that the dual-magnetic-layer structure with the low-M
_s
bottom layer is effective in increasing SNR of perpendicular media