Study of multiferroic properties in Bi5Fe0.5Co0.5Ti3O15 thin films

To explore the novel thin film with multiferroicity at room temperature, the bismuth-layer-structured Bi5Fe0.5Co0.5Ti3O15 (BFCT) thin films were prepared using chemical solution deposition technique. The microstructure, electric, and magnetic properties were investigated in BFCT film. A defined hysteresis loop of the BFCT film was obtained with the remnant polarization (2P(r)) similar to 31.7 mu C/cm(2) at 1 kHz under the electric field 300 kV/cm. To exclude contribution of the leakage current to polarization, we studied the dependence of hysteresis loops on the measuring frequency in the range from 100 Hz to 2 kHz and made the positive-up-negative-down (PUND) measurements in BFCT thin film. Both the results indicate the intrinsic ferroelectric property, and the leakage current does not play a big role in BFCT film. Meanwhile, the e-V curve can also support the natural ferroelectricity in the BFCT film. We also found that the BFCT film shows weak ferromagnetism with the saturated magnetization (M-s) similar to 2.6 emu/cm(3). Furthermore, the magneto-dielectric effect was observed with MDC similar to 0.39% at the frequency 100 kHz. The origin of weak ferromagnetism and the magneto-dielectric effect was discussed. VC 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4730892]