Highly resistive epitaxial Mg-doped GdN thin films
  We report the growth by molecular beam epitaxy of highly resistive GdN, using intentional doping with magnesium. Mg-doped GdN layers with resistivities of 1000 {\Omega}.cm and carrier concentrations of 10E16 cm-3 are obtained for films with Mg concentrations up to 5 x 10E19 atoms/cm3. X-ray diffraction rocking curves indicate that Mg-doped GdN films have crystalline quality very similar to undoped GdN films, showing that the Mg doping did not affect the structural properties of the films. A decrease of the Curie temperature with decreasing the electron density is observed, supporting a recently suggested magnetic polaron scenario [F. Natali et al., Phys. Rev. B 87, 035202 (2013)]. 
C.-M. Lee, H. Warring, S. V\'ezian, B. Damilano, S. Granville, M. Al   Khalfioui, Y. Cordier, H.J. Trodahl, B.J. Ruck, F. Natali
cond-mat.mtrl-sci cond-mat.str-el