Ferromagnetic Resonance Transmission in the Iron Group Metals

Abstract

This paper describes a two‐cavity microwave transmission experiment, carried out at a frequency of 35 GHz and a temperature of 4.2°K. A resonant transmission signal has been observed through thin sheets of the ferromagnetic metals permalloy and nickel when placed as the common end wall of the two TE₁₁₀ cavities. The transmitted signal occurs at an external magnetic field value appropriate to the antiresonance condition. It is better defined for the Permalloy sheets, due to the smaller line‐width, and in this case the resonance line shows a structure which is associated with an interference effect between electromagnetic waves and spin waves. A general theory of microwave transmission in ferromagnets is briefly presented, which includes spin‐wave and boundary condition effects, and an indication is given of the origin of the structure observed in this experiment as well as of further effects to be expected in experiments of this type.