Initial Layer Model for d /d Anomaly at 0-Field of In-Plane Magnetization in Perpendicular Recording Media

To evaluate properties of an initial growth layer for CoCrPt-SiO ₂ perpendicular recording media, an initial growth layer has been investigated by micromagnetic simulation with initial layer model. It was found that with the initial growth layer, the in-plane magnetization M_in shows a small jump at 0-field, leading to an additional peak around 0-field in 4 pi dM_in/dH curve. The (additional) peak height increases with the increase in inter- lower subgrain exchange areal energy densities w_i and thickness of the initial layer and also decreases in the anisotropy energy for the initial layer. Considering the change of the average anisotropy energy as a function of the thickness of recording layer, w_i for a CoCrPt-SiO₂ perpendicular recording medium with Ru/Ru-SiO₂ intermediate layer is in the range from 0.5 to 0.6 erg/cm² and roughly 30% smaller than those with a Ru intermediate layer