Yuzuru Hosoe

Effects of underlayer grain size on the microstructure of the magnetic layer in CoCrPt media

The average grain size of the CrTi or CrTiB underlayer was reduced from 16 to 7 nm and structural changes of the CoCrPt magnetic layer deposited on them were investigated. Reduction of the underlayer grain size tends to suppress the formation of bi-crystal clusters, though the magnetic layer has a CoCrPt (11.0) crystallographic texture. The average grain size of the magnetic layer showed a minimum when that of the underlayer was 9 nm. Further reduction of the underlayer grain size to 7 nm increased the average magnetic grain size about 15%. On the other hand, when the average underlayer grain size was less than 11 nm, the normalized standard deviation of the magnetic layer remained the same upon further reduction in the normalized standard deviation of the underlayer.

Pt-Cr Alloy Intermediate Layer for CoCrPt-SiO

We studied Pt-Cr binary alloys as a possible material for the intermediate layer (IML) in CoCrPt-SiO2 perpendicular recording media. We investigated the magnetic properties, structural properties, and recording performance of CoCrPt-SiO2 media with Pt-Cr alloy IMLs as a function of the Cr composition in the Pt-Cr IMLs. The CoCrPt-SiO2 media exhibited the best recording performance at the Cr composition from 20 to 30 at.%, where the structural and magnetic defects in the CoCrPt-SiO2 layers appeared to be minimized. Plan-view transmission electron microscopy images revealed that the addition of Cr into a Pt IML reduces the size of the crystal grains in the IML and promotes the formation of the oxide grain boundary in the CoCrPt-SiO2 layers.