A transition-metal–rare-earth alloy for perpendicular magnetic recording

Several Co-based media have been recognized to be convenient for perpendicular magnetic recording. These alloys present a good perpendicular magnetic anisotropy and high saturation magnetization, but high demagnetizing fields and a poor perpendicular hysteresis loop squareness σ⊥. This paper describes the conditions of deposition, magnetic properties, and recording tests results obtained with radio-frequence diode-sputtered FeTbGd thin films. Near to the compensation composition, the saturation magnetization and demagnetizing fields are low and σ⊥ is nearly 1. A SiO2 protective layer covered medium has been tested for magnetic recording with a conventional Winchester ferrite head. In these recording conditions, a density as high as 162 kiloflux changes per inch has been obtained. Such results show that transition-metal–rare-earth (TM-RE) alloys are suitable for perpendicular magnetic recording.