Back Cover (Phys. Status Solidi A 11/2010)
Elena Matei, Ionut Enculescu, Violeta Vasilache and Cristian Mihail Teodorescu
Version of Record online: 2 NOV 2010 | DOI: 10.1002/pssa.201090025
Elena Matei et al. (pp. 2517–2522) report on the growth of cobalt-doped zinc oxide thin layers by electrochemical deposition at different overpotentials. The films were investigated by scanning electron microscopy, optical spectroscopy, cathodoluminescence, X-ray photoelectron spectroscopy and Kerr magnetometry (MOKE). Some of the films, grown at highest overpotential (−850 mV) exhibited room temperature ferromagnetism – see back-cover images on the right. These are the samples with a small cobalt content and lowest structural perturbation of the ZnO matrix by cobalt. The cobalt-containing films exhibit a slight deviation in stoichiometry, having about 20% more metal atoms (Zn and Co) for an oxygen atom. Although the XPS data seem to indicate the formation of Co3O4 complexes, it is yet not clear whether the observed ferromagnetism belongs to such complexes, to Zn interstitials and/or to oxygen vacancies. Future X-ray absorption fine structure (XAFS) experiments are planned to elucidate the placement of Co ions in the ZnO lattice and the local atomic structure of the films.