Magnetic circular dichroism in EuTe in the ferromagnetic order

We investigated the polarized optical absorption near the band-edge of EuTe in high magnetic fields, for a ferromagnetic order of the S=7/2 spins in the Eu2+ lattice sites. In samples grown by molecular beam epitaxy, the Faraday geometry absorption spectrum is described by a doublet of narrow lines, which is characterized by a huge splitting (about 300 meV) for left and right circularly polarized light. The nature of these absorption lines is analyzed in the framework of the narrow d-conduction band model, and a comparison between theoretical and experimental absorption spectra is presented. Such a comparison allows us to provide a quantitative description of the excited electronic states responsible for the observed optical absorption, when the lattice spin order is ferromagnetic.