Reconstruction of the Magnetization in a Thin Film by a Combination of Lorentz Microscopy and External Field Measurements

Abstract

A combination of two measurements is shown to be sufficient to determine the magnetization in a thin film except for a constant out-of-plane component, under the condition that the magnetization is uniform through the thickness. The measurements consist of DPC Lorentz microscopy, which measures the path integral of the in-plane B field, and some measurement of the out-of-plane component of H above and below the film, for example by Hall probe. Field measurements on one side only are sufficient if the magnetization is in-plane. The in-plane magnetization is decomposed into a divergence-free part and a part with zero component of curl perpendicular to the plane of the film. The DPC measurement directly yields the divergence-free component, and the curl-free as well as the out-of-plane parts are found from a deconvolution of the perpendicular field. Several examples are given, and the interpretation of the two magnetization components in terms of B and H provides a qualitative description of the physics. © 1989 IEEE