Oxygen vacancy enhanced room temperature ferromagnetism in Al-doped MgO   nanoparticles
  We have investigated the room temperature ferromagnetic order that develops in Al-substituted magnesium oxide, Mg(Al)O, nanoparticles with Al fractions of up to 5 at.%. All samples, including undoped MgO nanoparticles, exhibit room temperature ferromagnetism, with the saturation magnetization reaching a maximum of 0.023 emu/g at 2 at.% of Al. X-ray photoelectron spectroscopy identifies the presence of oxygen vacancies in both doped and undoped MgO nanoparticles, with the vacancy concentration increasing upon vacuum annealing of Mg(Al)O, resulting in two-fold enhancement of the saturation magnetization for 2 at.% Al-doped MgO. Our results suggest that the oxygen vacancies are largely responsible for room temperature ferromagnetism in MgO. 
Debabrata Mishra, Balaji P. Mandal, Rupam Mukherjee, Ratna Naik, Gavin   Lawes, and Boris Nadgorny
cond-mat.mtrl-sci cond-mat.mes-hall cond-mat.str-el