Coexistence of ferroelectricity and ferromagnetism in BiFeO₃-BaTiO₃ thin films at room temperature

The (Bi_0.7Ba_0.3)(Fe_0.7Ti_0.3)O₃ solid solution films were fabricated by pulsed-laser ablation technique. The films exhibit both ferroelectricity and ferromagnetism above room temperature. Clear ferroelectric and ferromagnetic hysteresis loops were observed. The P_r is 2.5 μC/cm² and E_C is 533 kV/cm, and the residual magnetization (M_r) is 0.2 emu/g and coercive field (H_C) is 200 Oe, respectively. Film-thickness dependence of electric and magnetic properties is also examined. The dielectric constants of the film decreases with reducing the film thickness and the magnetic Curie temperature is almost constant independent of the film thickness.