Magnetic effects of periodic step-structures under permalloy/SAL thin films

Anisotropic magnetoresistance read devices may employ step-structures under a MR/SAL stack to aid in sensor stabilization. Thin film NiFe/SAL sheet MR elements with step-structures were studied using the magneto-optic Kerr effect with a goal to understand and control this sensor stabilization technology. The Kerr effect experimental data was compared to a micromagnetic simulation of the elements. Hard-axis magnetization curves and magnetic susceptibility were studied as a function of step-structure geometry. We find that the step-structures act as an effective anisotropy that increases with decreasing period or increasing depth or steepness. We discuss our conclusions with respect to design criteria and process control.