LAUSR

Abstract Bi4LaFeTi3O15 films were deposited on (111)Pt/Ti/SiO2/Si using a sol-gel process. The films have a four-layered Aurivillius structure with random orientation, which were confirmed by x-ray reflectivity and grazing incidence x-ray diffraction. As expected, the films show room-temperature multiferroic properties with a remanent polarization Pr of ∼17 μC/cm2 and a saturated magnetization Ms of ∼1.4 emu/cm3. More interestingly, a strong magneto-electric coupling was observed at room temperature with a converse magnetoelectric coefficient of 21% and a magneto-dielectric coefficient of 2%, resulting from the local Fe2+/Fe3+ charge ordering. Both x-ray photoelectron spectroscopy and temperature-dependent dielectric spectra provide evidence that the Fe2+ and Fe3+ coexist in Bi4LaFeTi3O15 films.