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, Y 0.74 Bi 0.25 FeO 2.97 (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 μ eff = 5.59 µ B , 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 ( P r ) of 0.27 μC cm –2 and electric coercivity ( E c ) 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.