Multiferroic properties of BiFeO_3/Bi_4Ti_3O_(12) double-layered thin films fabricated by chemical solution deposition

摘要

Multiferroic BiFeO_3/Bi_4O_(12) (BFO/BTO) double-layered film was fabricated on a Pt(111)/Ti/SiO_2/Si(100) substrate by a chemical solution deposition method. The effect of an interfacial BTO layer on electrical and magnetic properties of BFO was investigated by comparing those of pure BFO and BTO films prepared by the same condition. The X-ray diffraction result showed that no additional phase was formed in the double-layered film, except BFO and BTO phases. The remnant polarization (2P_r) of the double-layered film capacitor was 100 μC/cm~2 at 250 kV/cm, which is much larger than that of the pure BFO film capacitor. The magnetization-magnetic field hysteresis loop revealed weak ferromagnetic response with remnant magnetization (2M_r) of 0.4 kA/m. The values of dielectric constant and dielectric loss of the double-layered film capacitor were 240 and 0.03 at 100 kHz, respectively. Leakage current density measured from the double-layered film capacitor was 6.1 × 10~(-7) A/cm~2 at 50 kV/cm, which is lower than the pure BFO and BTO film capacitors.