XPS and Raman scattering studies of room temperature ferromagnetic ZnO : Cu

ZnO and Cu-doped ZnO nanocrystals have been synthesized by a sol–gel method. The nanocrystals have been investigated by XRD and all the particles are found to show the wurtzite structure. X-ray photoelectron spectroscopy and Raman scattering results provide evidence that Cu ions are mainly in the divalent state and incorporated into the ZnO lattice at Zn 2+ sites. Magnetic measurements reveal that the as-grown Zn 0.9894 Cu 0.0106 O nanocrystals exhibit room temperature ferromagnetic behaviour with the saturation magnetization of 0.0053 emu g −1 and the Curie temperature above 300 K.