High perpendicular magnetic anisotropy of CoPtCr/Ru films for granular-type perpendicular media

The perpendicular magnetic anisotropy [K.sub.u] of CoPtCr films deposited on Ru seed layers is discussed as a function of film composition. Moreover, the change in [K.sub.u] by the addition of [SiO.sub.2] is examined in light of thermal stability of CoPtCr-[SiO.sub.2] media. The [K.sub.u] of Co-10 at % Cr shows a high value of ~ 5 x [10.sup.6] erg/[cm.sup.3], which is much higher than that reported by Bolzoni et al The addition of Pt to the Co-10 at % Cr flint results in a further enhancement of [K.sub.u]. A maximum [K.sub.u] of nearly 10 x [10.sup.6] erg/[cm.sup.3] is observed at 25 ~ 30 at % Pt. All series of films with various Cr contents show maximum values of [K.sub.u] at 25 ~ 30 at % Pt. The maximum value for CoPt (Cr = O) films reaches ~ 15 x [10.sup.6] erg/[cm.sup.3]. The value of magnetocrystalline anisotropy of grains [K.sup.g.sub.u.], calculated by taking account of the volume fraction of CoPtCr grains, decreases as the [SiO.sub.2] content increases. However, the [K.sup.g.sup.u] maintains a large value of more than 7 x [106.sup.6] erg/[cm.sup.3], even at 10 at % [SiO.sub.2] in addition to ([Co.sub.90][Cr.sub.10])[sub.80] [Pt.sub.20], which indicates a high potential of CoPtCr-[SiO.sub.2] media to resist thermal agitation of magnetization. Index Terms--CoPtCr films, CoPtCr-[SiO.sub.2] media, perpendicular magnetic anisotropy, Ru seed layer, thermal agitation of magnetization.