Annealing modulated magnetism in double-perovskite PrBaMnFeO5.5+δ ferromagnetic insulator

Abstract Double-perovskite oxides are known to exhibit important electronic, magnetic, and electrochemical properties, including metal-insulator transition, colossal magnetoresistance, and excellent mixed conductivity. Here, single-crystalline PrBaMnFeO5.5+δ thin films were epitaxially grown and sensitively tailored to a tunable ferromagnetic state by post-annealing. The drastically tunable ferromagnetism is attributed to the detailed atomic microstructures, localized oxygen vacancy distribution, and exchange interactions between Mn and Fe ions with different valences. The as-grown PrBaMnFeO5.5+δ epitaxial film exhibits saturation magnetization twice that of undoped PrBaMn2O5.5+δ, probably owing to the synergistic reaction of Mn3+–O–Mn4+ double exchange and Mn3+–O–Fe3+ superexchange interactions. These findings suggest that the PrBaMnFeO5.5+δ double-perovskite film can be an effective ferromagnetic insulator with the strategic magnetic properties of complex manganite oxides tuned by chemical strains.