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.
@article{arxiv.1203.2991,
title = {Oxygen vacancy enhanced room temperature ferromagnetism in Al-doped MgO nanoparticles},
author = {Debabrata Mishra and Balaji P. Mandal and Rupam Mukherjee and Ratna Naik and Gavin Lawes and Boris Nadgorny},
journal= {arXiv preprint arXiv:1203.2991},
year = {2015}
}