Effects of magnetic layer thickness on negative nucleation field and Cr segregation behavior in CoCrPt/Ti perpendicular media

Abstract

Based upon our previous study on the formation of a large negative "nucleation field" in CoCrPt/Ti single layered perpendicular media (LS. Lee et al., J. Appl. Phys. 85 (1999) 6133), dependency of magnitude of negative nucleation field on CoCrPt/Ti with variation of Pt content and CoCrPt thickness was investigated. Difference in the degree of Cr segregation with the film thickness for a given film composition was also discussed. It was found that Cr segregation behavior might be closely associated with the nature of residual stress in the magnetic layer. When there was tensile stress in the film, Cr segregation was not significant. To understand the origin of the negative nucleation field, micromagnetic simulation was performed and it was found that a normalized nucleation field, H-n/K,(u) linearly depended upon K-u/M-s(2) and weakly depended on exchange parameter among grains when uniform grain size was assumed. Read/write simulation results show that a high negative nucleation field is effective in increasing the signal output.