Reduction of Co–Cr–Pt media noise by addition of Ti to Cr underlayer Available to Purchase

Effects of Ti addition to a Cr underlayer on the magnetic and crystallographic properties of Co–Cr–Pt media were investigated. C/Co–Cr₂₀–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 Co₇₂Cr₂₀Pt₈/Cr₇₅Ti₂₅ media was 20% lower than that of Co₆₈Cr₂₀Pt₁₂/Cr₉₀Ti₁₀ 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 Co₆₈Cr₂₀Pt₁₂ 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.