Microstructure and low temperature magnetic properties of NiZn-ferrite film

The soft magnetic Ni0.5Zn0.5Fe2O4(NZF) ferrite thin films were fabricated by sol-gel processing on polishing Si(100) substrate,and we analysed its microstructure and low temperature magnetic properties.The films exhibit single-phase spinel structure.The SEM photos indicate that the surface of the films is even and average particle diameter is about 30nm,which is coincident with that of XRD experiment analysis.Three different thin samples(90,120 and 210nm) are made separately.The film does exist the spin glass state at low temperature.The freezing temperature is about 140K in a field of 7.96×103A/m.The frozen spin degree decreases with increasing of the thickness.The results also show that the saturation magnetization and coercive forces of the films decrease with temperature increase at the temperature of 40～300K.The maximum magnetization is found at 40K.The reason that the saturation magnetizations of thinner film decrease under 40K is due to the surface spin of magnetic particles freezing partly and weaken the magnetic interionic spin coupling.