A Cr-Ti underlayer is found to enhance the in-plane coercive forces of Co-Cr-Pt and Co-Cr-Ta films; the maximum coercive force was 3.5 kOe for (CoCr0.15)0.84Pt0.16/CrTi0.2. The crystallites of Cr-Ti grow in a more highly oriented and uniform manner than ones of Cr, and their lattice spacings are closer to those of Co alloys than Cr, improving the epitaxial growth of Co-alloy crystallites with c-axis in-plane oriented components on the Cr-Ti underlayer. The crystalline anisotropy constant of Co-Cr-Pt with a high Pt concentration is found by torque measurement to be larger than that of Co-Cr-Ta. These can produce extremely high coercive forces in Co-Cr-Pt/Cr-Ti. The C/Co-Cr-Pt/Cr-Ti thin film media with high coercive forces show excellent read/write characteristics; the linear densities at 50% signal drop are very high, 175 and 101 kFCI, for the C/Co-Cr-Pt/Cr-Ti media at head-to-magnetic layer spacings of 0.01 and 0.07 μm.
Pin-on-disk wear tests on thin-film magnetic disks were performed using transparent materials. Quartz glass (QG), transparent zirconia (TZ), sapphire (SA), and synthesized diamond (DI) were used as pin materials. In addition to friction, sliding condition and pin wear were continuously monitored with video camera. Simultaneous friction measurement and video monitoring showed that friction dropped when wear debris intruded between pin and disk surfaces. Pin wear, from the measured diameter of wear scar on spherical pins, increased in the order of DI, SA, QG, and TZ. This order of pin wear does not coincide with that of the pin bulk hardness. Disk lifetime increased in the order of TZ, QG, SA, and DI, and the smaller the pin wear, the longer the disk lifetime.
Articles you may be interested inEffects of alloying additions in the CrMo underlayer on the grain size and magnetic properties of CoCrPt longitudinal mediaEffects of Ti addition to a Cr underlayer on the magnetic and crystallographic properties of Co-Cr-Pt media were investigated. C/Co-Cr 20 -Pt ͑Pt: 8 and 12 at. %͒/Cr-Ti ͑Ti: 0-30 at. %͒ films were deposited on textured Ni-P/Al-Mg substrates by dc magnetron sputtering. In-plane H c and S* increased as Ti was added to the Cr underlayer. The media noise at 167 kFCI decreased with an increase of the Ti content from 0 to 20 at. %. The normalized media noise of Co 72 Cr 20 Pt 8 /Cr 75 Ti 25 media was 20% lower than that of Co 68 Cr 20 Pt 12 /Cr 90 Ti 10 media where their coercivity and S* were almost the same. Further increase of the Ti caused the increase of the media noise. Transmission electron microscopy studies showed that average grain size of Cr-Ti films decreased from 30 to 20 nm with the increase of the Ti content from 0 to 20 at. %. The activation volume of Co 68 Cr 20 Pt 12 films measured from the time dependences of remanence coercivity decreased by 30% as the Ti content increased from 0 to 20 at. %. The reduction of media noise is probably due to the decrease of the magnetic switching volume which is caused by the reduction of the grain size of Cr-Ti underlayers.
The crystal structure and magnetic properties of Co-alloy films deposited by KrF excimer laser ablation were investigated. A pulsed laser beam with wavelength of 248 nm was focused onto the deposition targets which were fixed in the vacuum chamber. Cr underlayer and Co-alloy films were successively deposited at a rate of 0.012 nmipulse. The film surface was microscopically smooth compared to the sputtered films. This may be due to the low-shadowing effect during the laser deposition. The composition of the film was reproducibly controlled, though there was a slight difference between the composition of film and target material. The coercivities of Co-Cr-Pt/Cr films formed on the Si and Ni-P substrates at 250 "C were 130 and 220 Oe, which were about one-fifth of the coercivity of sputtered films. Crystallographic analyses showed that Cr underlayer had no crystal orientation, and Co-alloy film consisted of fine fee-type crystal grains. Low coercivity of the laser-deposited film is probably due to the lack of hcp Co phase.
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