Motoharu Sato

Co alloy media made on amorphous carbon substrate

Co‐based alloy media were made on recently developed ultra densified amorphous carbon (UDAC) substrates which have several advantages over NiP/Al, glass, and ceramics substrates. It was found that the coercivity (Hc) of media made on UDAC substrates was higher than that on NiP/Al substrates, as was the adhesion performance. The latter is a result of the formation of Cr–C compound at the interface.

Process temperature dependence of ∂M plots on Co alloy media on amorphous carbon substrates

The static magnetic properties and the film structure of Co alloy recording media made under different deposition and annealing temperatures were investigated. With increasing film coercivity an increase of the grain size and a reduction of the positive peak in the ∂M plots were observed. It is believed that reduced exchange coupling was achieved by preferential Cr segregation at the grain boundaries during high‐temperature processing.

Ultra densified amorphous carbon (UDAC) substrate for hard disks

An ultra-high temperature HIP method was applied for amorphous carbon to eliminate micro pores, which amorphous carbon generally has. Ultra densified amorphous carbon (UDAC) substrate has many favourable characteristics for hard disk substrates, and mechanical texturing methods, which are generally used in texturing of NiP/AI substrates, can be applied. High coercivity can be obtained by using a circumferentially textured UDAC substrate.