Probing proximity effects in the ferromagnetic semiconductor EuO

Ferromagnetic insulators are widely employed to induce magnetic phenomena in adjacent layers via proximity effect. This approach could make non-magnetic materials (ranging from silicon to graphene) available for spintronic applications. Eu chalcogenides, EuO in particular, are highly efficient spin generators but suffer from low Curie temperatures. Here, experiments aimed at T_C increase in EuO by its integration with the ferromagnetic metal Gd are reported. The epitaxial bilayers Gd/EuO are synthesized on different substrates and characterized by a combination of diffraction and microscopy techniques. Their magnetic structure – established with magnetization and transport measurements as well as element-selective X-ray magnetic circular dichroism study – comprises coupled magnetic orders of EuO and Gd. EuO is robust against proximity effects – its T_C is still low, increased at most by a few tens of K. Nevertheless, the results encourage further studies of proximity-enhanced ferromagnetism to extend the range of applications of ultrathin layers of EuO in spintronics.