Enhanced Room-Temperature Ferromagnetism Observed in SiO2-Coated CuO Nanostructures

Abstract

In this paper, the magnetic properties of pure CuO and SiO2-coated CuO nanocrystals were reported. Strongly enhanced room-temperature ferromagnetism was observed in SiO2-coated CuO nanocrystals, whose saturation magnetization is two orders of magnitude enhanced compared to that of the uncoated CuO nanocrystals. The mechanism of this enhancement was investigated. It points out the main origin of ferromagnetism in these CuO nanocrystals is the uncompensated surface state, so that the coating of SiO2 can effectively protect the surface state to improve the ferromagnetism in these CuO nanocrystals.