Post-annealing effects on the physical properties of CoFe ₂O ₄-PbZr _0.48Ti _0.52O ₃ composite films prepared by using pulsed laser deposition

CoFe ₂O ₄(CFO)-PbZr _{0. 48}Ti _{0. 52}O ₃(PZT) composite films deposited on LaNiO ₃(LNO) coated SrTiO ₃ substrates by using laser ablation with a CFO-PZT composite target were post-annealed in an oxygen gas environment at various temperatures from 500 °C to 900 °C. The CFO-PZT composite bulk showed a chemical reaction behavior between two phases at above 1100 °C while the composite film exhibited such a behavior at a much lower temperature of 900 °C. As the postannealing temperature increased up to 800 °C, X-ray diffraction peaks become sharper, and grains with clean boundaries appeared, indicating that the crystalline property of the CFO-PZT composite film was improved. At 800 °C, a Au/CFO-PZT/LNO capacitor exhibited minimal leakage currents at low voltages and significantly improved ferroelectric and ferrimagnetic properties. At 900 °C, however, the multiferroic properties of the CFO-PZT composite film had completely disappeared. Our study will be a guide to optimize the post-annealing conditions for CFO-PZT composite films.