Investigation of multiferroic behaviour at room temperature in Bi-induced orthoferrite: combined experimental and first principles studies

Perovskite oxides are an important and exciting class of materials owing to the structural diversity with remarkable magnetic, optical and electronic behaviours. Here, a single-phase multiferroic orthoferrite, Y0.74Bi0.25FeO2.97 (YBFO), has been synthesized by a conventional solid-state method. The crystal structure was refined using the Rietveld refinement method from powder X-ray diffraction data, and confirms an orthorhombic structure with the Pnma space group. The Curie-Weiss fitting to the magnetic susceptibility shows that the θ-value is –926 K and μeff = 5.59 µB, exhibiting canted antiferromagnetism. Room temperature magnetic and ferroelectric hysteresis loops verify the presence of magnetic as well as ferroelectric ordering in the material with a remnant polarization (Pr) of 0.27 μC cm–2 and electric coercivity (Ec) of 15 kV cm–1. Temperature-dependent P–E loops and pyrocurrent response confirm the inherent multiferroic nature of the material. The UV–visible study indicates a semiconductor nature with the bandgap of 1.86 eV. Density-functional theory calculations support the observed experimental behaviour and it signified the role of Bi-substitution. Even a very less concentration of Bi-doping can form an exciting room temperature multiferroic material.