Soft x-ray magnetic circular dichroism study on Gd-doped EuO thin films

We report on the growth and magnetic properties of Gd-doped $\mathrm{EuO}$ thin films. We prepared samples with Gd concentrations up to $11%$ by means of molecular beam epitaxy under distillation conditions. Using soft x-ray magnetic circular dichroism at the Eu and Gd ${M}_{4,5}$ edges, we found that ${T}_{C}$ ranges from $69\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for pure stoichiometric $\mathrm{EuO}$ to about $170\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for films with the optimal Gd doping of around $4%$. The doping dependence of ${T}_{C}$ has been investigated and compared with available theoretical predictions. We also show that the Gd magnetic moment couples ferromagnetically to that of Eu.