Valence state of Sm in single-crystalline EuO thin films A. Reisner, D. Kasinathan, S. Wirth, L. H. Tjeng and S. G. Altendorf EPL, 117 4 (2017) 47001 Published online: 06 April 2017 DOI: 10.1209/0295-5075/117/47001