Multiferroic properties of sol-gel-derived Bi4LaFe0.5Co0.5Ti3O15 thin films of four-layered perovskite

Polycrystalline Bi4LaFe0.5Co0.5Ti3O15 (BLFCTO) thin films were prepared on (111)Pt/Ti/SiO2/Si via a sol-gel process. The films have a single-phase four-layered Aurivillius structure with space group Fmm2. As expected, the BLFCTO films present room-temperature multiferroic properties with a remanent polarization 2P (r) of similar to 42 mu C cm(-2) and a saturated magnetization M (s) of similar to 7.2 emu cm(-3). More interestingly, both dielectric relaxation behavior and room-temperature magneto-dielectric effect were observed in the BLFCTO films, probably resulting from the charge ordering of Fe2+ and Fe3+. The magneto-dielectric coefficient of similar to 3.8% was obtained at room temperature under a low magnetic field of 0.5 T.