Sputter-epitaxy and electric properties of multiferroic Bim + 1Fem-3Ti3O3m + 3 thin films

Growth conditions suitable for sputter-epitaxy of Bim + 1Fem-3Ti3O3m + 3 (BFTO) thin films with layered structure have been investigated. The amount of oxygen during deposition was found to be specifically essential for obtaining a good-quality thin film of BFTO with a large m. The (001) epitaxial thin films of BFTO with m of nearly 10 which is expected to retain magnetic order up to room temperature have been successfully grown on (001) SrTiO3 substrates under the determined optimum condition. The film exhibited leakage current as low as order of 10−2–10−1 A/m2 limited by Schottky emission at the interfaces between the electrodes and the film. In addition, the film showed a ferroelectric polarization curve with Pr = 6 μC/cm2 for applied field of 35 MV/m at room temperature though the curve was unsaturated. These indicate that the BFTO (m = 10) thin films are promising as multiferroics at room temperature.