Room-temperature multiferroic Bi4YFeTi3O15 thin films of four-layered perovskite

Polycrystalline Bi4YFeTi3O15 thin films were prepared on (111)Pt/Ti/SiO2/Si through a sol-gel process. X-ray diffraction analysis shows the films have a single-phase four-layered Aurivillius structure with the space group of Fmm2. As expected, the Bi4YFeTi3O15 films exhibit the coexistence of ferroelectric and weak ferromagnetic properties with the remanent polarization (2Pr) ∼ 53.62 μC/cm2 and the saturated magnetization (Ms) ∼ 0.50 emu/cm3 at room temperature. More interestingly, both dielectric relaxation behavior and room-temperature magneto-dielectric effect were observed in the Bi4YFeTi3O15 films, probably resulting from the coexistence of Fe2+ and Fe3+. The conduction mechanism of the films from 10 to 300 kV/cm is dominated by Ohmic mechanism, space-charge-limited current (SCLC), and trap-filled-limit (TFL) current, respectively. The leakage current density remains lower than 1.03 × 10−5 A/cm2 under the poling field below 300 kV/cm at 300 K.