Physical and chemical strains co-tuned magnetic properties of double perovskite PrBaMn_2O_(5.5+δ) epitaxial films

摘要

Different layered perovskite-related oxides are known to exhibit important electronic, magnetic, and electrochemical properties including metal-insulator transition, colossal magnetoresistance, excellent mixed ionic/electronic conductivity, and especially their flexible tunability by external or internal stimuli. Here, we show that the microstructure and magnetic properties of double perovskite PrBaMn2O5.5+delta (PBMO) epitaxial films can be co-tuned by the physical strain via a proper choice of substrate and film thickness and the chemical strain from the concentration of oxygen vacancies. It is surprisingly found that the films with more oxygen vacancies reveal more Mn4+ formed along with Mn2+ under the influence of interface strain, and meanwhile, Mn4+ exhibits a thickness-dependent distribution with a high amount at the interface. Consequently, the increased proportion of Mn4+ diminishes the saturation magnetization and decreases the Curie temperature of PrBaMn2O5.5+delta epitaxial films, revealing the availability of physical and chemical strains tuning the properties of highly epitaxial double perovskite films.