Strain driven structural phase transformation and correlation between structural, electronic, and magnetic properties of Bi1−xBaxFeO3 (0 ≤ x ≤ 0.30) system

In this study a series of Bi1−xBaxFeO3(0 ≤ x ≤ 0.30) multiferroic samples have been prepared and a correlation between structural, electronic and magnetic properties has been drawn. Systematic changes in Mössbauer parameters with Ba2+ concentration are observed. Mössbauer spectroscopy results confirmed the presence of Fe3+ oxidation state which suggests the presence of oxygen vacancies in the system. Ba2+ ion substitution driven structural transition from rhombohedral to cubic symmetry (R3c→Pm3¯m) has been confirmed from Rietveld refinement results. It is observed that the R3c and Pm3¯m coexisting phases persists up to x = 0.30. This structural transformation leads to enhanced saturation magnetization due to suppression of spiral spin structure. Moreover, we demonstrate that local lattice distortions induced by size mismatch between the host and the dopant and presence of oxygen vacancies produced by aliovalent (Ba2+) doping in BiFeO3 also results in a systematic increase in magnetization by affecting the FeOFe canting angle. The observed decrease in values of magnetic coercivity at low temperatures is suggested to be indicative of magnetoelectric coupling in these multiferroic samples.