Ferromagnetism in ZnCoO due to Hydrogen-Mediated Co-H-Co Complexes: How to Avoid the Formation of Co Metal Clusters?

Abstract

There have been many studies of ferromagnetism in ZnCoO, and the results have been controversial. Secondary phases, such as Co oxides and Co metal clusters, in ZnCoO are easily produced during treatment, but the formation conditions are not well understood. We fabricated samples under hydrogen-injection conditions at different heat-treatment temperatures and examined the conditions by using synchrotron X-ray analysis under which Co3O4 appeared or was transformed into Co metal. We investigated the transforming process of the ferromagnetic origin from intrinsic to extrinsic nature via intermediate region competition by Co-H-Co and Co metal cluster and suggest conditions that induce ferromagnetic spin ordering in ZnCoO due to Co-H-Co complexes through hydrogen mediation.