Finite-Element Analysis of Stress Induced Magnetic Anisotropy in Perpendicular Writers

This paper presents finite-element analysis of the stress-induced magnetic anisotropy in perpendicular magnetic recording (PMR) heads developed during fabrication. The intrinsic stresses of various thin films used in the heads were measured using wafer curvature, while the stress in the yoke region was measured using X-ray diffraction. The measured stresses are provided. The initial strains due to the intrinsic stresses in the films were modeled using equivalent thermal strains and the calculations were verified by correlations with the stress measurements. Finite-element simulations were performed for calculating the stresses in full PMR heads. Detailed simulation procedures are described. Computed results are presented on how sensitive the magnetic anisotropy in the write pole are to the pole tip length and the slider lapping and the compressive stress in overcoat as well as the ambient temperature