Effect of substrate induced strains on the magnetic and ferroelectric properties of epitaxial bilayer thin films of lead zirconate titanate and cobalt ferrite

Epitaxial bilayer thin films of cobalt ferrite (CFO) and lead zirconium titanate (PZT) were deposited on MgO (100) and SrTiO$_{3}$ (STO) (100) substrates by pulsed laser deposition. The structural properties were characterized using X-ray diffraction and atomic force microscopy. The magnetic properties were measured at 10 K and 300 K in both parallel and perpendicular magnetic fields. The CFO-PZT bilayers showed enhanced or reduced magnetization compared to the single layer CFO films depending on the substrate of deposition. The ferroelectric properties of the CFO-PZT bilayers showed enhanced polarization compared to PZT single layer films on both types of substrates. A strain compression-relaxation mechanism was proposed in order to explain the structure-property relationships in the CFO-PZT bilayers.