Crystal structure and magnetic properties of rf-sputtered Cu–Zn ferrite thin films

Abstract

Cu–Zn ferrite (Cu0.6Zn0.4Fe2O4) thin films were deposited using rf-magnetron sputtering on glass substrates at room temperature in pure Ar gas environment. The influence of variation in Ar gas pressure between 5 and 15 mT on the crystal structure and magnetization has been studied. The XRD patterns show single phase nanocrystalline spinel structure with cubic symmetry. The AFM images also confirm the nanocrystalline nature of the films. The magnetization increases with increase in Ar gas pressure. The change in the crystal structure and magnetization has been explained in view of freezing of some Cu-ions on tetrahedral A-sites and equivalent number of Fe ions on octahedral B-sites during the deposition process due to high deposition rate in pure Ar environment. Furthermore, the deposition in reducing (argon) atmosphere may lead to the formation of Cu+ ions that prefer occupation of the smaller four-coordinated A-site in the spinel structure and displace Fe3+ cations to occupy the B-sites. The formation of Fe2+ cannot be ruled out in the spinel structure where a fraction of Fe3+ will be replaced by Fe2+ ions.