The objective of this experiment is the study and characterization of spin-polarized electron states at the interface of EuO and 3d transition metal oxides. EuO is a ferromagnetic semiconductor with conduction-band electronic states which have a spin polarization above 90%, making it a very interesting material for spintronics. Our research will proceed along two complementary routes: 1. a study of the formation of a quasi-two-dimensional electron gas at the interface between EuO and LaAlO3, which has been predicted to be spin-polarized below the Curie temperature of EuO; 2. a study of the possibility to induce ferromagnetism in EuO above its Curie temperature, thanks to proximity effects with Fe or Fe3O4, which have recently been discovered in a related system. We propose to analyze these interfaces by Polarized Neutron Reflectometry.