Dimensional Effects Resulting from a High Dielectric Constant Found in a Ferromagnetic Ferrite

Abstract

A variety of a ferromagnetic ferrite is shown to have dielectric properties corresponding to a dielectric constant of the order of ${10}^5$. Coupled with a magnetic permeability of about ${10}^3$, this leads to dimensional resonance effects such that the apparent permeability of a core whose section is 2.5×1.25 cm reduces to very low values in the region of 2 megacycles. An apparent anomaly exists in the dielectric behavior in the vicinity of the magnetic Curie point. A general theory of dimensional effects encountered in measuring magnetic and dielectric constants is developed. This theory is based on the geometry of the infinite slab. When the theory is applied to the ferrite under study, a residual variation of the permeability with frequency remains, which may be explained by magnetic resonance. The theory accounts adequately for the dielectric effects at the Curie point.