Orientation-Dependent Properties of CoFe2O4-Bi3.15Nd0.85Ti3O12 Bilayer Multiferroic Films Prepared by a Sol-Gel Method

Lead-free bilayer multiferroic films of CoFe2O4 (CFO) and oriented Bi3.15Nd0.85Ti3O12 (BNT) were deposited on a conventional Pt(111)/Ti/SiO2/Si(100) substrate by use of a sol-gel method. BNT layers with different preferred orientations were grown by use of different spinning and annealing processes. The ferroelectric, ferromagnetic, and magnetoelectric (ME) properties of the CFO-BNT bilayer thin films were investigated at room temperature. a-Axis-oriented bilayer films had larger ME voltage coefficients and larger converse ME response than c-axis-oriented films. This study shows that the orientation of the BNT layer has a stress-mediated interfacial effect which can substantially affect the magnetoelectric coupling behavior of the bilayer structures.