Room-temperature magnetoelectric coupling in Bi4LaFeTi3O15 multiferroic films.

Bi 4 LaFeTi 3 O 15 films were deposited on (111)Pt/Ti/SiO 2 /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 P r of ∼17 μC/cm 2 and a saturated magnetization M s of ∼1.4 emu/cm 3 . 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 Fe 2+ /Fe 3+ charge ordering. Both x-ray photoelectron spectroscopy and temperature-dependent dielectric spectra provide evidence that the Fe 2+ and Fe 3+ coexist in Bi 4 LaFeTi 3 O 15 films. [ABSTRACT FROM AUTHOR]