Large Faraday effect in a short wavelength range for disordered zinc ferrite thin films

We have prepared a zinc ferrite (ZnF2O4) thin film 85nm thick deposited on a silica glass substrate by using a radio frequency sputtering method. Faraday effect measurements have been carried out not only for as-deposited but also for annealed thin films. The thin film annealed at 300°C as well as the as-deposited thin film exhibit a large Faraday rotation angle at a wavelength of around 390nm. In particular, the thin film annealed at 300°C manifests the largest Faraday effect among the present thin films; the rotation angle of 1.65°∕μm is attained at a wavelength of 386nm. The thin films 1.08μm thick exhibit a large magnetization at room temperature, and the dependence of the magnetization on the external magnetic field is suggestive of a ferrimagnetic behavior.