A facile way to regulating room-temperature ferromagnetic interaction in Co-doped ZnO diluted magnetic semiconductor by reduced graphene oxide coating

Realizing room-temperature ferromagnetic interactions in diluted magnetic semiconductors is a precondition to future application of next-generation spin-based information technologies. However, searching capable methods to tailor the inherent magnetic coupling is still a great challenge. Here, a strategy for effective manipulating the ferromagnetism of 1% Co doped ZnO (Co-ZnO) is developed. Graphene oxide (GO) was coated on the surface of Co-ZnO, and was in-situ reduced by hydroxylamine, which brought about larger oxygen vacancy density and significant changes in saturation magnetization, due to the hybridization of π orbits of reduced GO and 3d orbits of Co2+. The structure and origin of the ferromagnetism have been investigated by XRD, SEM, HREM, UV-Vis, FTIR, XPS, and PPMS. And the saturation magnetization of Co-ZnO increased from 0.002 to 0.013 emu·g−1 after coated by reduced GO. This strategy may provide a new way for regulating the density and nature of defects in ZnO, and open up a possibility to manipulate the ferromagnetism of diluted magnetic semiconductors.