Room-temperature multiferroic properties in 1.5LaFeO3–Bi4Ti3O12 thin films

Abstract

Random-oriented 1.5LaFeO3–Bi4Ti3O12 thin films were fabricated on (111)Pt/Ti/SiO2/Si(100) substrates by a sol–gel method. Both X-ray diffraction and Raman spectroscopy characterizations confirm that the films have a single-phase Aurivillius structure with 4–5 successive perovskite blocks. The films exhibit room-temperature multiferroic properties with the remanent polarization 2P r ~ 27.20 µC/cm2 and saturated magnetization M s ~ 4.28 emu/cm3. Moreover, room-temperature magneto-dielectric effect with magneto-dielectric coefficient of ~ 1.03% was observed, which arises from the charge ordering of Fe2+ and Fe3+. Theoretical analysis of temperature-dependent dielectric spectrum and X-ray photoelectron spectroscopy data reveals a major contribution of charge ordering of Fe2+ and Fe3+ to the magneto-dielectric effect in 1.5LaFeO3–Bi4Ti3O12 thin films.