High Perpendicular Magnetic Anisotropy of CoPtCr/Ru Films for Granular-Type Perpendicular Media

Abstract

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 /spl sim/5/spl times/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 film results in a further enhancement of K/sub u/. A maximum K/sub u/ of nearly 10/spl times/10/sup 6/ erg/cm/sup 3/ is observed at 25/spl sim/30 at % Pt. All series of films with various Cr contents show maximum values of K/sub u/ at 25/spl sim/30 at % Pt. The maximum value for CoPt (Cr=0) films reaches /spl sim/15/spl times/10/sup 6/ erg/cm/sup 3/. The value of magnetocrystalline anisotropy of grains K/sub u//sup g/, calculated by taking account of the volume fraction of CoPtCr grains, decreases as the SiO/sub 2/ content increases. However, the K/sub u//sup g/ maintains a large value of more than 7/spl times/10/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.