Enhanced ferroelectricity in NaNbO3–LaCoO3:Mn epitaxial thin film

Abstract

A (001)-oriented NaNbO₃–LaCoO₃:Mn thin film with enhanced ferroelectric properties was successfully deposited on a SrRuO₃-buffered LaAlO₃ substrate by radiofrequency magnetron sputtering. This epitaxial thin film modified by element doping shows a tetragonal ferroelectric structure and large remanent polarization (31 μC cm⁻²) with high Curie temperature (450 °C). The polarization fatigue tests demonstrate an improved fatigue resistance due to the reduced oxygen vacancies by element doping. Further X-ray absorption spectra experiments found that the split energy between Nb t_2g and e_g orbitals is reduced and the hybridization between transition metal d-O 2p is strengthened, leading to enhanced ferroelectric polarization.