Defect-Mediated Magnetism in Pure CaO Nanopowders

Abstract

The intrinsic nature of ferromagnetism in CaO nanopowders has been established with the experimental observation of magnetic hysteresis loop at room temperature. On the basis of the results of X-ray diffraction, magnetic properties, positron annihilation lifetime spectra, and first-principles calculations, it is found that there are correlations among the lattice constant, the defect concentration, and the magnetization of CaO nanopowders, which suggests that Ca defects are the main reason for the magnetic order and the defect concentration is related with the ferromagnetism. Such a ferromagnet without the presence of any transition metal could be a very good option for a class of spintronics.