Role of defects in BiFeO_3 multiferroic films and their local electronic structure by x-ray absorption spectroscopy

摘要

Present study reports the role of defects in the electrical transport in BiFeO_3 (BFO) multiferroic films and its local electronic structure investigated by near-edge X-ray absorption fine structure. Defects created by high energy 200 MeV Ag~(+15) ion irradiation with a fluence of ～5 × 10~(11) ions/ cm~2 results in the increase in structural strain and reduction in the mobility of charge carriers and enhancement in resistive (I-V) and polarization (P-E) switching behaviour. At higher fluence of ～5 × 10~(12) ions/cm~2, there is a release in the structural strain due to local annealing effect, resulting in an increase in the mobility of charge carriers, which are released from oxygen vacancies and hence suppression in resistive and polarization switching. Near-edge X-ray absorption fine structure studies at Fe L_(3, 2)- and O K-edges show a significant change in the spectral features suggesting the modifications in the local electronic structure responsible for changes in the intrinsic magnetic moment and electrical transport properties of BFO.