High Frequency Permeability of Mn-Zn Ferrite and its Composite Materials

Abstract

Complex permeability spectra (μ*=μ'-iμ") in Mn-Zn ferrite and its composite materials have been studied. In sintered ferrite, resonance-type frequency dispersion was observed at room temperature but decrement of μ' is steeper than that of ordinary resonance. As the temperature is decreased, onset frequency of dispersion shifts higher and dispersion character changes to relaxation-type. In ferrite composite materials, relaxation characters were also observed at low volume loading samples. Since Mn-Zn ferrite has relatively high electrical conductivity at room temperature, high frequency permeability is suppressed by eddy current. However, lowering of temperature and reduction of ferrite content result in the decrease of eddy current; magnetic resonance such as relaxation-type spin rotational one appears in high frequency region.