Multiferroic ZnO obtained by substituting oxygen with nitrogen

N-doped ZnO films were prepared in nitrogen plasma by pulsed laser deposition. Clear room temperature ferromagnetism has been observed in the film prepared at a substrate temperature of 500 °C. The structural characterizations of X-ray diffraction, Raman, and X-ray photoelectron spectroscopy confirm the substitution of O by N in ZnO, which has been considered to be the origin of the observed ferromagnetism. Furthermore, ferroelectricity has been observed at room temperature by piezoelectric force microscopy, indicating the potential multiferroic applications.