Origin of enhanced multiferroic properties in Dy and Co co-doped BiFeO3 ceramics

Abstract

Structural, magnetic and fermelectric properties of polycrystalline BiFeO3, Bi0.9Dy0.1FeO3. BiFe0.97Co0.03O3 and Bi0.9Dy0.1Fe0.97Co0.03O3, which were prepared by solid-state method, have been investigated. The X-ray diffraction (XRD) patterns reveal that all the samples are in single phase and show rhombohedrally distorted perovskite structure with R3c space group. Both XRD and Raman scattering studies show that Dy and Co co-doped sample has a compressive lattice distortion induced by co-substitution of Dy and Co ions at the A and the B sires, respectively. Dy and Co co-doping favors weak ferromagnetism ordering with evident magnetic hysteresis loop and enhances magnetization values at room temperature. Ferroelectric hysteresis loop for Dy and Co co-doped sample shows the nearly saturated polarization at 40 kV/cm and large remnant polarization. Dy dopant is prominent in the reduced leakage current density, while Co dopant is remarkable in the improved remnant magnetization in Bi0.9Dy0.1Fe0.97Co0.03O3 ceramic. By using a simple model, it was found that the anharmonicity of canted spiral cycloidal spin structure was responsible for the weak ferromagnetism of pure BiFeO3, and the enhanced magnetization in Co-doped sample was attributed to the transition from the incommensurate cycloidal spiral spin structure towards the G-type canted collinear antiferromagnetic structure. (C) 2014 Elsevier BY. All rights reserved.