Optical Analysis of Magnetization Process Dependence on Film Depth for Perpendicular Thin-Film Media.

Heterogeneity of the perpendicular magnetization process dependence on film depth for CoNiCrTa and CoCrTaPt perpendicular thin-film media is discussed based on a magneto-optical analysis. Results show that: (1) by means of longitudinal Kerr equipment, evaluation for separating longitudinal magnetization of a columnar structure and initial layer is possible; (2) in a perpendicular magnetization process, the top of the medium has high coercive force and high squareness compared with the bottom of the medium; and (3) the top of the medium has homogeneous magnetization thicker than 25 nm, and the bottom has a thickness of about 10 nm. The top and bottom of the medium are considered to be a columnar structure and initial layer, respectively.