Hysteresis loops of the energy band gap and effective g factor up to 18,000 for metamagnetic EuSe epilayers

Hysteresis effects of the fundamental energy gap as a function of applied magnetic field are studied for metamagnetic EuSe layers grown by molecular-beam epitaxy. Below the phase transition temperature, the energy gap show large step-like red shifts of up to 150 meV with increasing magnetic field with pronounced hysteresis effects when the change in the magnetic field is reversed. Both, the steps and the hysteresis loops are caused by transitions between the aniferro-, ferri-, and ferromagnetic phases in EuSe. The large redshift of the band gap is directly proportional to the magnetization of the sample and results from the Zeeman spin splitting of the conduction band. The corresponding effective g factor deduced from our experiments reaches values up to 18 000 at the magnetic phase transitions. (C) 2004 American Institute of Physics.