Magnetoelectric coupling effect of Ga0.8Fe1.2O3/Bi0.5(Na0.85K0.15)0.5TiO3 multiferroic composite films

Lead-free Ga0.8Fe1.2O3/Bi0.5(K0.15Na0.85)0.5TiO3 (GFO/BKNT) bilayer multiferroic composite films were fabricated on Pt(100)/Ti/SiO2/Si substrates via sol-gel methods. The microstructure, domain structure, ferroelectric, piezoelectric, magnetic properties as well as magnetoelectric coupling effect were investigated for the composite films at room temperature. Well-defined interfaces between GFO and BKNT layers and clear electric domain structures are observed. A strong magentoelectric effect is obtained with magnetoelectric voltage coefficient of αE=30.89 mV/cm Oe, which is attributed to excellent ferroelectric, piezoelectric, and magnetic properties, as well as the coupling interaction between ferromagnetic GFO and ferroelectric BKNT phases for lead-free bilayer composite films. Besides, GFO and BKNT demonstrate the similar perovskite structure with well lattice matching, which endows the outstanding coupling and fascinating magnetoelectric properties. The present work opens up the opportunity of lead-free magnetoelectric composite films for both further fundamental studies and practical device applications such as sensors, transducers and multistate memories.