Advantageous use of metallic cobalt in the target for pulsed laser deposition of cobalt-doped ZnO films

We investigate the magnetic properties of ZnCoO thin films grown by pulsed laser deposition (PLD) from targets made containing metallic Co or CoO precursors instead of the usual Co₃O₄. We find that the films grown from metallic Co precursors in an oxygen rich environment contain negligible amounts of Co metal and have a large magnetization at room temperature. Structural analysis by X-ray diffraction and magneto-optical measurements indicate that the enhanced magnetism is due, in part, from Zn vacancies that partially compensate the naturally occurring n-type defects. We conclude that strongly magnetic films of Zn_0.95Co_0.05O that do not contain metallic cobalt can be grown by PLD from Co-metal-precursor targets if the films are grown in an oxygen atmosphere.