Magneto-optical study of the Verwey transition in magnetite

We have made the first detailed Faraday measurements on thin films of Fe3O4 for 10<T<500 K. The measured magneto-optic spectra and the diagonal component of the dielectric constant are used to obtain the complex off diagonal component of the dielectric constant, exy, which is analysed for the changes in the energy, oscillator strength, and width of the transitions. A significant anomaly is seen in these optical parameters within about 10 K of the Verwey temperature. However, there are also some differences between the optical parameters above and below Tv over a wider temperature range. The results are interpreted to give valuable information on the orbital ordering.