Femtosecond optical orientation triggering magnetization precession in epitaxial EuO films

Light-induced magnetization response unfolding on a temporal scale down to femtoseconds presents a way to convey information via spin manipulation. The advancement of the field requires exploration of new materials implementing various mechanisms for ultrafast magnetization dynamics. Here, pump-probe measurements of EuO-based ferromagnets by a time-resolved two-colour stroboscopic technique are reported. Epitaxial films of the pristine semiconductor and metallic Gd-doped EuO demonstrate photo-induced magnetization precession. Comparative experimental studies of both systems are carried out varying temperature, magnetic field, and polarization light helicity of the pump beam, followed by numerical estimates. The study establishes optical spin orientation by the electronic transition 4f⁷5d⁰ → 4f⁶5d¹ as a mechanism triggering collective magnetization precession in these materials. The results suggest applications of EuO-based systems in optoelectronics and spintronics.