Sadao Hishiyama

Modulation and crystallographic orientation of sputtered CoNi/Cr disks for longitudinal recording

Origins of readback signal modulation are investigated. Modulation is proportional to the amount of magnetic anisotropy energy and the effects of the magnetic field up to 50 Oe and substrate rotation up to 30 rpm on the modulation are negligible. Average in-plane magnetic properties of CoNi/Cr films are determined by the ( 10\bar{1}1 ) preferred orientation of CoNi films which are epitaxially grown on

Read and write characteristics of Co-Ni-Zr-M/Cr thin films for longitudinal recording

The magnetic and crystallographic properties and read and write characteristics of sputtered C/Co-Ni-Zr/Cr and C/Co-Ni-Zr-M/Cr (M=V, Nb, Ta, Cr, Mo, W, Cu, Si, Al, Ru and Pt) thin films are investigated. The saturation magnetic flux density B/sub s/ of all C/Co-Ni-Zr-M/Cr films decreases as the amount of additive element increases. The coercivity of C/Co-Ni-Zr-Cr/Cr and C/Co-Ni-Zr-Pt/Cr is higher than that of C/Co-Ni-Zr/Cr films with comparable B/sub s/. The larger the perpendicular anisotropy K/sub p/ and the smaller the anisotropy constant K/sub n/, the lower the media noise N and the higher the S/N ratio. The reduction of K/sub n/ and N are strongly connected to grain separation and grain size reduction. The larger the B/sub s/.tmag, the higher E/sub II/ and N and the lower D/sub 50/ and the S/N ratio. All films except those with Si, Ru, and Pt additives have large K/sub p/, a small K/sub n/, and a high S/N ratio. In particular, C/Co-Ni-Zr-M/Cr (M=Cr, Mo, W, and Al) disks have a better S/N ratio and D/sub 50/ than C/Co-Ni-Zr/Cr disks. >

Magnetic properties and corrosion-resistance of sputtered Co-Ni and Co-Ni-M films for longitudinal recording

The magnetic properties and corrosion resistance of sputtered Co-Ni/Cr and Co-Ni-M/Cr (M=Zr,Cr, Mo,Pt) thin films are investigated. Although pitting corrosion occurs on Co-Ni, Co-Ni-Mo, Co-Ni-Cr, and Co-Ni-Pt films for 1 mol/l NaCl spray tests, Co-Ni-Zr film exhibits almost no pitting because of total surface passivation. Furthermore, Co-Ni-Zr/Cr films show relatively high magnetization, high coercive force, and high squareness, which are suitable for longitudinal recording.

Microstructure and mechanical properties of metal-alloy nitride (M/sub I/M/sub II/)N overcoats for rigid disks

Mechanical durability and microstructures are investigated for metal alloy nitride overcoats consisting of (M/sub I/M/sub II/)N, where M/sub I/=Ti or Zr and M/sub I/=V, Nb, or Ta. The overcoats are prepared by conventional reactive RF sputtering. It is demonstrated that stoichiometric nitrides are formed for a nitrogen content at or higher than 50 vol.% in a nitrogen-argon gas mixture during deposition. The average grain sizes of Zr-based alloy nitrides are 4 to 5 nm, while those of Ti-based alloy nitrides are 10 to 13 nm. The mechanical durability of the Zr-based alloy nitrides is much higher than that of the Ti-based ones. Overcoats of (Zr/sub 1-x/Nb/sub x/)N show the highest durability; this occurs at a Nb content, x, of 0.4 to 0.6. Zirconium-niobium nitrides exhibit a durability higher than that of conventional carbon overcoats in both pin-on-disk and continuous slow-grinding tests. This is due to the smaller grain size and more durable oxidized surface layer in the zirconium-niobium nitride films. The zirconium-alloy nitride overcoats thus exhibit the most promising mechanical properties for rigid-disk application. >