Sci. Rep. 3, 1333 (2013)

The europium chalcogenides (EuO, EuS, EuSe and EuTe) have long been known for their simple rock-salt structure as well as their rich magnetic and magneto-optic properties. They are also wide-bandgap semiconductors that, in combination with their magnetism, makes them potentially interesting for spintronic applications. As for most ferromagnetic semiconductors, however, ensuring they remain magnetic up to room temperature is a stumbling block. Spiridon Pappas et al. now present a possible way for achieving this. The trick is to take advantage of their polarizability in proximity to a ferromagnet. By fabricating multilayers consisting of cobalt and EuS they observe, by means of X-ray magnetic circular dichroism, a significant magnetic signal associated with the europium ions at room temperature. The magnetic response is a direct signature of substantial spin-polarization in the EuS, and suggests manipulating both the electron spin and its charge may be feasible in these materials in the future.