Strong magnetoelectric coupling of Aurivillius phase multiferroic composite films with similar layered perovskite structure

Aurivillius phase Bi5Ti3FeO15/Na0.5Bi4.5Ti4O15 multiferroic composite films were synthesized using a sol-gel technique. Multiferroic properties and magnetoelectric coupling effect of composite films were investigated. The domain structures were clearly observed, which prove that composite films endow with good ferroelectric polarization. The maximum piezoelectric coefficient is up to 235 pm/V at 20 V, which proves that good electrostrictive and piezoelectric properties are obtained. The composite films exhibit enormous magnetoelectric voltage coefficient with αE = 410 mV/cm·Oe in magnetic field of Hbias = 7.6 kOe at room temperature, which is ascribed to good ferromagnetic, piezoelectric properties and interface coupling between Bi5Ti3FeO15 and Na0.5Bi4.5Ti4O15 layers. This work not only provides a new idea but also greatly improves the magnetoelectric effect of composite films, which makes magnetoelectric effect more effective in practice.