Ferroelectric and Magnetoelectric studies of doped and co doped Bismuth ferrites

Abstract

Bismuth ferrite (BFO) is a multiferroic material that shows ferroelectricity and ferromagnetism at room temperature. It is widely used in spintronics and memory storage devices. The rhombohedral cell of BFO consists of two perovskite cells in which Bi3+ are at the corners and Fe3+ are at the center of FeO6 octahedra, and connected along the [111] direction. The hybridization between 6s2 lone pair of Bi3+ and 2p orbitals of O2and#8722; leads to displacement of Bi3+ along [111] direction. This is responsible for ferroelectricity and antiparallel spin orientation of Fe3+ leading to Gtype antiferromagnetism. Various synthesis techniques, temperature treatments, and doping mechanisms play important roles in the tuning of multiferroic properties. In this present work, the structural modifications of the Holmium doped and Holmium, Manganese co-doped samples prepared through the solid-state route method and their impact on the electrical, magnetic, and magnetoelectric properties are explained in detail. Holmium-doped samples show a structural transition from rhombohedral to orthorhombic (P bnm) structure while co-doped samples are slightly distorted. The dielectric behavior of all the samples exhibits dispersion due to the grain and grain boundary effect. This dielectric dispersion is a characteristic feature of ferroelectric materials. Doped samples exhibited better ferroelectric loops due to the reduction in leakage current. At the same time, co-doped samples show lossy nature in the PolarizationElectric Field hysteresis loop due to the presence of impurity phases and oxygen vacancies. Temperature-dependent dielectric anomaly indicates the magnetic ordering of the prepared sample. Magnetic studies of all the doped samples show the presence of ferromagnetism at room temperature and antiferromagnetism at higher temperatures. With respect to co-doping this magnetic nature gradually disappears and the sample shows antiferromagnetic ordering. Also, the doped and co-doped samples show enhancement in Magnetoelectric (ME) coupling than the pure BFO. Pure and doped Bismuth ferrite samples were simulated using Material Studio software. CASTEP and DMol3 modules were used for the Band structure, density of states, and Optical properties analysis. The obtained value of the lower band gap indicated its applicability in photo voltaic devices. newline