Interface double-exchange ferromagnetism in the Mn-Zn-O system:: New class of biphase magnetism -: art. no. 217206

In this Letter, we experimentally show that the room temperature ferromagnetism in the Mn-Zn-O system recently observed is associated with the coexistence of Mn3+ and Mn4+ via a double-exchange mechanism. The presence of the ZnO around MnO2 modifies the kinetics of MnO2 -> Mn2O3 reduction and favors the coexistence of both Mn oxidation states. The ferromagnetic phase is associated with the interface formed at the Zn diffusion front into Mn oxide, corroborated by preparing thin film multilayers that exhibit saturation magnetization 2 orders of magnitude higher than bulk samples.