Microstructural and ferromagnetic properties of Zn1−xCuxO thin films

Room temperature ferromagnetism is observed in Zn1−xCuxO (x=0.01, 0.03, and 0.05) thin films grown on Al2O3 substrates by pulsed laser deposition technique. Raman scattering and high resolution transmission electron microscopy analyses confirm the substitution of Cu up to 3% in ZnO host lattice, and the films are nearly single crystalline. Optical transmission and photoluminescence (PL) analyses provide evidence of sp-d exchange interaction in Zn1−xCuxO thin films; the p-d exchange interaction may explain the observed room temperature ferromagnetism in Zn1−xCuxO thin films. Room temperature PL shows the green emission (∼2.60 eV) in Cu doped ZnO samples.