Microstructure effect on magnetization and domain structure in Ni0.49Zn0.49Co0.02Fe1.90Ox ferrite

The effect that grain size has on magnetization in cobalt substituted NiZn polycrystalline bulk ferrite has been studied and the magnetic domain has been visualized by taking measurements with a Photoemission Electron Microscope (PEEM). Complex permeability shows that magnetization with a grain size smaller than ∼6 μm is dominated only by the spin rotation and the magnetic domain wall motion contributes when the grain size is larger. PEEM measurements show that the small grain induces the small magnetic domain and it becomes larger when the grain is large, which is a result that agrees with the magnetization process. At the same time, the presence of a domain wall across the grain boundary has been confirmed regardless of the grain size. This suggests the possibility of there being a magnetic coupling between the grains related to the effect that the microstructure has on magnetic domain structure and magnetization in cobalt substituted NiZn ferrite. - Highlights: • We examined the grain size effect on magnetization in NiZn ferrite. • Magnetic domain structure in NiZn ferrite was visualized by PEEM. • Magnetization with small grain is dominated by spin rotation and it seems to single magnetic domain. • Domain wall motion contributes to the magnetization with large grain. • Domain wall across the grain boundary was confirmed regardless of the grain size