Coexistence of ferromagnetism and paramagnetism in ZnO/CuO nanocomposites

In this letter, the room-temperature ferromagnetic behavior in the ZnO/CuO nanocomposites has been reported. The composites composed of ZnO and CuO with different ratios were prepared by hydrothermal method. X-ray diffraction (XRD) and selected area electron diffraction (SAED) confirmed that these composites were made up by wurtzite ZnO and monoclinic CuO. X-ray photoelectron spectroscopy (XPS) indicated that Cu ions on the surface of the materials were in a divalent state. Magnetic measurements showed that all ZnO/CuO composites possessed room-temperature ferromagnetism, while pure ZnO was diamagnetic. With the increase of CuO content in the composites, ZnO/CuO composites displayed the coexistence of ferromagnetism and paramagnetism, and paramagnetism was gradually enhanced and dominated later.