Strain induced enhancement of erasable domain wall current in epitaxial BiFeO3 thin films

Abstract

The characteristic of electronic transport at the ferroelectric domain boundary is intensively studied for the potential application in random access memory due to its unique resistance switching mechanism along with polarization reversal. Such high conductivity in artificially created domain walls is not only affected by the material defect chemistry, such as oxygen vacancies, but also pertinent to the multiple polarization states of the sample. Here, we show the enhanced domain wall current in BiFeO3 thin films that could be obtained by the optimization of epitaxial strains from substrates. The leakage current analysis reveals the electronic transport of domain wall current in line with the space-charge-limited conduction mechanism. It is believed that the uncompensated polarization charge arouses the band bending at the domain boundary, which profoundly affects the wall current. Free carriers are easily concentrated in the domain boundary region for the compensation of the enhanced polarization by the strain, resulting in an abrupt increase of the conductivity.