Ferroelectricity in Pulsed Laser Deposited Ba(Fe_1/2Nb_1/2)O₃ Thin Films

Complex perovskite Ba(Fe_1/2Nb_1/2)O₃ thin films are grown on Pt/TiO₂/SiO₂/Si substrates by pulsed laser deposition. Non-linear polarization–electric-field (P–E) loops are observed at low temperatures under different electric fields and frequencies. The broad peak in the corresponding current density–electric field (J–E) loop confirms the existence of domain switching. The remnant polarization decreases slightly when the temperature decreases from 153 to 123 K, which differentiates Ba(Fe_1/2Nb_1/2)O₃ from normal ferroelectrics. The Raman spectra of Ba(Fe_1/2Nb_1/2)O₃ thin films show two-mode-like behavior in the high-wavenumber region, which can be caused by the local chemically heterogeneous zones of NbO₆ and FeO₆. The weak ferroelectricity observed in the Ba(Fe_1/2Nb_1/2)O₃ thin films might originate from the composition fluctuation and subsequent symmetry breaking in the material. The present results might provide a new aspect to the understanding of the intrinsic dielectric nature in Ba(Fe_1/2Nb_1/2)O₃.