FeCoC film as the soft magnetic underlayer for perpendicular media

FeCoC granular thin films are prepared and studied as the soft magnetic layer in order to obtain a low noise double-layered perpendicular recording medium. FeCoC granular soft magnetic underlayer prepared by cosputtering at room temperature showed good soft magnetic properties; with coercivity of a few oersteds and Bs of 1.4–1.7 T. Using a spin-stand and a ring-type head, sharper transitions can be obtained in the [Co/Pd]n media with an FeCoC soft underlayer at higher recording density compared to media without a soft magnetic layer. No spike noise was observed in the read back signals for [Co/Pd]n media with an FeCoC granular film as the soft magnetic underlayer. Preparing the [FeCo/C]n laminated films by alternately sputtering FeCo and C layers allows the properties of the films to be flexibly adjusted. A Bs of 1.9 T with relative permeability of 100–400 and coercivity lower than 40 Oe can be obtained with laminated [FeCo/C]n (210 nm) multilayer thin films.