Magnetization Decay in CoCr-alloy Perpendicular Magnetic Recording Media

Abstract

The magnetization decay in CoCr-alloy perpendicular magnetic recording media has been investigated. Both remanent magnetization and recorded signal output decay rates of CoCrPtTa medium increase with decreasing magnetic layer thickness. The decay rates can be kept small by controlling the microstructure of magnetic layer by employing a CoCr35/TiCr 10 dualunderlayer. CoCrPt media with the dual-underlayer have high Mr/Ms ratio (Mr/M s > 0.95) and show little decay of remanent magnetization and recorded signal output, though the magnetic layer is very thin (25 nm) and is composed of small grains. It is possible to prepare perpendicular media comprising a Co-based alloy with Mr/Ms > 0.95, which is an important factor to suppress the recorded signal decay rate within an acceptable level.

Overview of latest work on perpendicular recording media

“…Large is also preferable for keeping thermal stability of residual magnetization of perpendicular recording media. The significant effect of larger on thermal stability of the magnetization was also confirmed by experiments [3], [4]. The perpendicular demagnetizing field in the media is reduced when the recorded density is increased.…”

“…Films with were obtained by M. Futamoto [3] for Co-Cr-Pt using Ti-Cr 10 underlayer, and the domain size was reduced by using double layered underlayer with Co-Cr 35 and Ti-Cr 10 . Co-Cr-Ta films with a large greater than 0.8 were also prepared using the same double layered underlayer.…”

Advancements in PMR thin-film media

“…In 1997, S ¼ 1 was obtained by Hirayama et al [11] in HCP CoCrPt media using a TiCr 10 under layer and the /D*S was reduced using an intermediate layer ( 10 . Vacuum post-annealing 3 h at segregated Cr to grain boundaries to reduce the magnetic noise but did not increase 12 nm grain size.…”

Effects of very thin carbon seedlayer on formation of hcp phase for CoCrPtB/Co/sub 60/Cr/sub 40/ perpendicular magnetic recording media

“…As an attempt to increase , elimination of initial growth layer in CoCr-based recording layer by using epitaxial growth on Cr-rich CoCr-based intermediate layer has been reported [2]- [5]. However, few papers discussed the relationship between the improvement of the magnetic properties and the structure of CoCr intermediate layer.…”