Magnetization analysis of Ba ferrite magnets by electron holography

The magnetization distributions of anisotropic and isotropic Ba ferrite magnets in demagnetized and remanent states are investigated by electron holography. A polar diagram is used to obtain the quantitative mapping of the magnetization distribution. Through the polar diagrams, it is clarified that the magnetization distribution of Ba ferrite magnets closely depends on their magnetic properties. The dispersions of the magnetization direction of the two specimens in the remanent states correlate well with their remanent flux density. In the anisotropic specimen, the magnetization reversal occurs drastically under an applied field of 360 kA/m, while in the isotropic one, the direction of magnetization changes gradually. The results exhibit a good correspondence between the change in the magnetization distribution and the shape of the demagnetization curves. (C) 2007 Elsevier B. V. All rights reserved.