Contribution of magnetization mechanisms in nickel-zinc ferrites with different grain sizes and its temperature relationship

By adjusting the duration time of sintering, nickel-zinc (NiZn) ferrites with gradually varied grain sizes have been fabricated by the solid-state reaction method and their magnetization mechanisms and temperature dependence were investigated. In order to manifest the variation of permeability, the dominant magnetization mechanism was investigated by resolving the complex permeability spectra into two components including domain wall movement and spin rotation magnetization. The results show that, with grain size increasing, the dominant contribution to magnetization mechanism changes from spin rotation magnetization to domain wall movement due to the increase of amount of domain wall, and the amount of domain wall is observed by Lorentz microscopy to measure the critical diameter of magnetic domain which is around 3 μm in NiZn ferrite. The temperature dependence of the magnetization mechanism has been discussed for the sake of thermal stability. As the operating temperature increases, the ratio between two magnetization mechanism components appears to be stable around 4 after a shift from 1.76, and the domain wall movement totally dominates the variation of permeability as the main magnetization mechanism.