Magnetic characteristics and recording properties of thin Co-CoO metal evaporated tapes

Metal Evaporated Media

“…For systematic studies on the effect of medium thickness, adjusting the substrate speed has been the most straightforward method. Different study on the evolution of media properties with film thickness have been reported, covering a large range of thicknesses (Arisaka et al, 1991;Motohashi and Onodera, 2003;Motohashi et al, 2001;Pan and Spratt, 1995;Xu et al, 2001). For media of thickness larger than 50 nm, the saturation magnetization (M s ) and coercivity (H c ) are found to be almost constant with the magnetic layer thickness (Arisaka et al, 1991;Motohashi et al, 2001;Xu et al, 2001).…”

“…At large oxygen flow rates, there are more CoO crystallites separating the Co columns leading to narrower column widths. In addition, within the columns, the size of the Co crystallites decreases and their shape become more isotropic (Gau and Ytter, 1987;Hokkyo et al, 1993;Sato et al, 1991;Xu et al, 2001). At the optimum oxygen flow rate, the medium is particle like, with very fine Co crystallites well decoupled in the nonmagnetic matrix of CoO grains.…”

“…The oxygenation process during deposition is critical in controlling the microstructure of the evaporated film and in turn its magnetic properties. This is first evident in the evolution of the film saturation magnetization and coercivity as a function of the oxygen flow rate (Chiba et al, 1989;Hokkyo et al, 1993;Motohashi et al, 2001;Sato et al, 1991;Xu et al, 2001). Figure 2.4 presents one example for the continuous incident evaporation of Co with a medium thickness of about 100 nm .…”

“…With increasing oxygen flow rates, the saturation magnetization decreases almost linearly while the film magnetic coercivity increases. Sufficiently large oxygen flow rates are required to achieve the optimum magnetic and recording properties (Chiba et al, 1989;Hokkyo et al, 1993;Motohashi et al, 2001;Sato et al, 1991;Xu et al, 2001). The coercivity finally decreases at too large oxygen flow rate due to an almost complete oxidation of the film.…”

Tribochemistry of Ionic Liquid Lubricant on Magnetic Media

“…The tape used is a PET substrate with an evaporated film of Co which is typically 100 nm thick. The magnetic layer fabricated with oxygen gas has obliquely aligned fine particles ( Figure 1) [9,10], which leads to higher electromagnetic characteristics [11,12]. The carbon overcoat and the lubricant layer are deposited onto the magnetic layer in a similar way to the rigid disks [13].…”