Effects of Cr–N–ZrO 2 seed layer formed on glass substrates for longitudinal recording media

Abstract

Effects of Cr–N–ZrO 2 seed layer deposited on glass substrates before the deposition of C/Co–Cr–Pt/Cr–Ti layers for longitudinal recording media have been investigated. The product of v and I s, the activation volume and the saturation magnetization per unit volume, media noise N d and S 0/ N d, which is the half value of peak-to-peak output voltage of an isolated pulse over N d at 11.8 kFC/mm, are evaluated. We find that vI s is decreased by adding N and ZrO 2 to Cr seed layer. N d is reduced as vI s decreases by adding nitrogen to the Cr seed layer. This is mainly due to the decreased grain sizes of both Cr–Ti underlayer and Co–Cr–Pt magnetic layer. The N d is further reduced by the addition of ZrO 2 to the Cr–N seed layer. Highest S 0/ N d is achieved for the media with Cr–N–ZrO 2 seed layer. On the other hand, the media with Cr–ZrO 2 seed layer deposited without nitrogen show the higher N d. Therefore the decrease of the grain size by addition of nitrogen into Ar is essential to reduce N d, and the ZrO 2 addition to the Cr–N seed layer seems to enhance the effect of grain size reduction by nitrogen addition.