Observations of Magnetic Losses in a Single Crystal of a Ferromagnetic Conductor

Abstract

An exact correlation between material parameters and magnetic losses in ferromagnetic conductors has been very elusive, due partly to the fact that losses normally are measured on polycrystalline material. Even if the material is highly textured, the domain structure is sufficiently nonregular and wall motion is sufficiently sporadic that accurate correlation is very difficult. Recent observations have also shown that the dynamic domain structure can be significantly different from that observed statically. Thus, a technique was developed to measure magnetic losses on small single crystals with well-defined domains as a function of frequency and induction. Measurements were made on thin crystals of a 3% iron-silicon alloy {with an (001) [100] orientation} having a slablike domain structure parallel to one of the two 〈100〉 directions in the surface. Losses were measured in both 〈100〉 directions and were correlated with the dynamic domain structure observed by the Kerr magneto-optic effect and high-speed photography. The losses reflect the influence of the dynamic domain-wall spacing, wall nucleation, and annihilation.