Formation of NiZn ferrite nano-crystalline thin films by rf magnetron sputtering with changing substrate temperatures

Thin films of NiZn ferrite, Ni0.5Zn0.5Fe2O4, were formed on the substrate of quartz glass plate by rf magnetron sputtering by changing the substrate temperatures during the sputtering from 200 to 700 °C. The size of the NiZn ferrite crystallites composing the film was exhibited to be controlled from less than 10 nm to about 40 nm by the change of the substrate temperature. The formed nano-crystalline NiZn ferrite thin film with the crystalline size of ∼40 nm showed constant magnetic permeability up to ∼2 GHz, indicating the possibility of nano-crystalline ferrite thin films as the materials for magnetic devices workable in GHz-frequency region.