Structure and multiferroic properties of multi-doped Bi1−xErxFe0.96Mn0.02Co0.02O3 thin films

Abstract

Multiferroic Bi1−xErxFe0.96Mn0.02Co0.02O3 (BExFMCO, x = 0.08–0.12) thin films have been successfully prepared on fluorine doped tin oxide (FTO) substrates by the chemical solution deposition method. The structural characteristics of the thin films were investigated by X-ray diffraction (XRD), Rietveld refinement and Raman spectra, indicating a structural transition from typical rhombohedral-R3c:H (BFO) to two-phase coexistence of triclinic-P1 and orthorhombic-Pbmn (BE0.12FMCO). XPS analyses suggest there is the coexistence of Fe2+ and Fe3+ ions in all the thin films. The multi-doping exhibits small effects on oxygen vacancies due to the complex effects of doping ions. Intensive super exchange between Fe2+ and Fe3+ and the decreased leakage current densities are observed in BE0.1FMCO thin films. Multi-doped thin films show the superior ferroelectric properties with a giant remanent polarization (the BE0.1FMCO thin film with Pr∼104.43 μC/cm2). The enhanced ferroelectric properties of BExFMCO thin films can be mainly attributed to the structural transition via doping. The highest magnetization values of Ms∼9.78 emu/cm3 and Mr∼2.1 emu/cm3 are obtained in the BE0.1FMCO thin films, which can be attributed to the super exchange between Fe2+ and Fe3+ ions and the altered space modulated spin structure due to structural transition.