Multiferroic properties of aurivillius structure Bi4SmFeTi3O15 thin films

Bi4SmFeTi3O15 thin films were coated on (111)Pt/Ti/SiO2/Si substrates by the sol–gel method. X-ray diffraction analysis shows the films have a single-phase four-layered Aurivillius structure with the space group of A21am. The remarkable physical property of Bi4SmFeTi3O15 thin films are the presence of multiferroic properties at room temperature with the remnant polarization (2Pr) ~ 48 μC/cm2 and saturated magnetization (Ms) ~ 0.43 emu/cm3. Moreover, at room temperature, magnetoelectric coupling that may be derived from the charge order of Fe3+ and Fe2+ is observed. Magnetodielectric coefficient and magnetoelectric coefficient are respectively 0.78% at 0.5 T and 41.16 mV/cmOe at 0.9 T. The coexistence of Fe2+ and Fe3+ was confirmed with both X-ray photoelectron spectra and dielectric relaxation spectrum.