Enhancement of ferromagnetic properties in Zn0.98Cu0.02O by additional Co doping

• The samples were synthesized by sol–gel technology to dope up to 3% Co in ZnCuO.
• After Co doped into Zn0.98Cu0.02O sample photoluminescence shows an increase in green emission.
• The saturation magnetization increased with Co doping.

Zn0.98Cu0.02O and Zn0.95Cu0.02Co0.03O powders were synthesized by sol–gel method, and the effects of Co codoping on the structure, optical and magnetic properties of the Zn0.98Cu0.02O powders were studied in detail. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurement shows the Zn0.98Cu0.02O and Zn0.95Cu0.02Co0.03O powders were single phase with the ZnO wurtzite structure, and there was no ferromagnetic-related secondary phase in these powders. Moreover, these powders exhibited ferromagnetism at the room temperature investigated by the magnetic measurement, and the ferromagnetism of the Zn0.98Cu0.02O and Zn0.95Cu0.02Co0.03O samples were originated from the fact that the Cu ions and Co, Cu ions doped into the ZnO lattices, respectively. In addition, the saturation magnetization (Ms) was significantly increased with Co codoping due to the increased density of oxygen vacancies.