Magnetic field induced polarized optical absorption in europium chalcogenides

The optical absorption spectrum of EuTe epitaxial layers grown by molecular beam epitaxy was studied at low temperatures and high magnetic fields, using circularly polarized light. At high magnetic fields a narrow line (width 41 meV) emerges at the low energy side of the absorption threshold. The line shows a huge displacement with magnetic field and is attributed to a magnetic exciton. The emergence of this line has a strong effect on the Faraday rotation, which becomes strongly non‐linear.