Soft x-ray magnetic circular dichroism study on Gd-doped EuO thin films
  We report on the growth and characterization of ferromagnetic Gd-doped EuO thin films. We prepared samples with Gd concentrations up to 11% by means of molecular beam epitaxy under distillation conditions, which allows a very precise control of the doping concentration and oxygen stoichiometry. Using soft x-ray magnetic circular dichroism at the Eu and Gd M4,5 edges, we found that the Curie temperature ranged from 69 K for pure stoichiometric EuO to about 170 K for the film with the optimal Gd doping of around 4%. We also show that the Gd magnetic moment couples ferromagnetically to that of Eu. 
H. Ott, S. J. Heise, R. Sutarto, Z. Hu, C. F. Chang, H. H. Hsieh,   H.-J. Lin, C. T. Chen, and L. H. Tjeng