Multifarious-magnetism in copper oxide nanostructures from first-principles

Driven by the ever-increasing demand for novel spin-dependent advanced materials, investigation of nanoscale magnetic materials is currently actively pursued. With the latest developments focusing more on magnetic semiconducting oxides, materials based on cuprous oxide, Cu$_2$O, are of high interest as potential $p$-type semiconducting candidates. Thus developing an understanding of how intrinsic defects influence both its electronic and magnetic properties is important. We perform density-functional theory calculations [1] and analyze both the electronic and magnetic properties of native defects in both bulk Cu$_2$O and its surfaces, as well as their respective formation/surface energies under different growth conditions. We find that under oxygen-lean conditions, the experimentally observed ferromagnetic behaviour [2] could originate from copper vacancies on Cu$_2$O(111) while under oxygen-rich conditions, low energy bulk oxygen interstitials might explain the ferromagnetic moment found in the same material. This suggests that the origin of observed magnetism in sub-stoichiometric copper oxide nanoparticles could be multifarious, highlighting the complimentary role of bulk and surface native magnetic defects.\\[0pt] [1] A. Soon \textit{et al}. submitted\\[0pt] [2] A. Ye. Yermakov\textit{et al.} J. Magn. Magn. Mater. \textbf{310}, 2102 (2007)