Growth and characterization of spinel-type magnetic semiconductor ZnCo2O4 by reactive magnetron sputtering

We report the synthesis of spinel oxide ZnCo2O4 thin films and the effects of the oxygen partial pressure in the sputtering gas mixture on their electrical and magnetic properties. The conduction type and carrier concentration were found to be dependent on the oxygen partial pressure ratio: n-type and p-type for the oxygen partial pressure ratio below similar to70% and above similar to85%, respectively. A ferromagnetic coupling was observable in p-type ZnCo2O4, whereas an antiferromagnetic interaction was found for insulating and n-type ZnCo2O4 film, revealing hole-mediated ferromagnetic transition in ZnCo2O4. Arrott plot analysis of magnetization data at 5 K also indicated non-zero spontaneous magnetization for p-type ZnCo2O4. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.