Conduction mechanisms and enhanced multiferroic properties of Sr doped Bi0.85−xPr0.15SrxFe0.97Mn0.03O3 thin films

Abstract

Pure BiFeO3 (BFO) and Bi0.85−xPr0.15SrxFe0.97Mn0.03O3 (BPSxFMO, x = 0.02–0.05) thin films were deposited on fluorine-doped SnO2 (FTO/glass) substrates by a sol–gel method. The systematic studies of crystalline structure, surface morphologies, leakage conduction mechanisms, ferroelectric and magnetic properties of pure BiFeO3 and Bi0.85−xPr0.15SrxFe0.97Mn0.03O3 thin films were investigated. X-ray diffraction patterns, Rietveld analysis and Raman scattering spectra reveal that the (Pr, Sr and Mn) co-doped BiFeO3 thin films give rise to a trigonal (R3m: R) structure transition with respect to the original rhombohedral structure of pure BiFeO3 film. Fowler–Nordheim tunneling conduction mechanism dominates the leakage current of all the films in the relatively high electric field. The significantly enhanced ferroelectric properties of the Bi0.85−xPr0.15SrxFe0.97Mn0.03O3 thin films were observed in comparison with pure BiFeO3 film. In addition, the BPS2FMO film shows the enhanced ferromagnetism with the saturation magnetization (Ms ~ 1.97 emu cm−3), which is almost three times larger than that of pure BFO film (Ms ~ 0.67 emu cm−3), as a result of the small grain size effect and the collapse of space modulated spin structure by the structure transition.