Analysis of write field distribution in permalloy recording head

Abstract

The magnetization and the write field configuration in permalloy heads are analyzed based on the micromagnetic torque equation. Instead of solving the nonlinear integro-differential equation directly, Fourier method is used to simplify the computation of the magnetostatic term. The method is esentially an extension of Dove's,1 by taking into account both the exchange coupling and the air gap. The equilibrium state for the magnetization and its induced stray field around the air gap must be solved for by the inversion of an N×N matrix (N=number of harmonics for the Fourier series), arising from the N linear equations approximating the nonlinear differential equations. The magnetization configuration in the head and the write field (both longitudinal and transverse) distribution are calculated as functions of air gap length, film thickness, anisotropy field of the film, magnetic path length along the head, and drive current, etc. Finally, a number of applications for the present method are also indicated. © 1970 The American Institute of Physics.