Comparison of structural and electric properties of PbZr _0.2Ti_0.8O₃ and CoFe₂O ₄/PbZr_0.2Ti_0.8O₃ films on (100)LaAlO₃

In this work, we investigated structural, electrical, and magnetic properties of ferroelectric PbZr_0.2Ti_0.8O₃ (PZT) and ferrimagnetic/ferroelectric [CoFe₂O₄(CFO)/PZT] bilayers grown on (100)LaAlO₃ (LAO) substrates supplied with bottom 50 nm thick LaNiO₃ electrodes. Interestingly, structural and electrical properties of the PZT layer exhibited remarkable changes after the top-layer CFO deposition. X-ray diffraction data suggested that both the c- and a-domains exist in the PZT layer and the tetragonality of the PZT decreases upon the top-layer deposition. A variation in the electrical properties of the PZT layer upon the CFO deposition was investigated by polarization versus voltage (P-V), capacitance versus voltage (C-V), and capacitance versus frequency (C-f) measurements. The CFO deposition induced a slight decrease of the remnant polarization and more symmetric behavior of P-V loops as well as led to the improvement of fatigue behavior. The tentative origin of enhanced fatigue endurance is discussed based on the measurement results. These results were corroborated by local piezoelectric measurements. Ferrimagnetic property of the CFO/PZT bilayer was confirmed by magnetic measurement at room temperature.