Influence of the substrate temperature on the Curie temperature and charge carrier density of epitaxial Gd-doped EuO films

Rare earth doping is a standard, yet experimentally poorly understood method to increase the Curie temperature (T-C) of the ferromagnetic semiconductor EuO. Here, we report on the charge carrier density (n) and the T-C of commonly used 4.2 at. % Gd-doped EuO films grown by molecular-beam epitaxy on (110) oriented YAlO3 substrates at various substrate temperatures (T-sub). Increasing T-sub leads to a decrease in n and T-C. For high substrate temperatures the Gd-doping is rendered completely inactive: n and T-C drop to the values of undoped EuO. (C) 2011 American Institute of Physics. [doi:10.1063/1.3563708]