Bias-polarity-dependent asymmetric domain switching in fatigued epitaxial BiFeO3 (001) capacitors

Abstract

We investigated domain switching dynamics in pristine and fatigued epitaxial BiFeO3 (001) capacitors using piezoresponse force microscopy and switching current measurements. In contrast to domain growth-dominant switching in the pristine capacitors, we observed two different bias-polarity-dependent switching dynamics in the fatigued capacitors. Under a positive bias on the top electrode of the fatigued capacitors, the domain walls were strongly pinned, indicating that nucleation played a critical role in domain switching. However, when a negative bias was applied, the domain wall velocity decreased owing to weak pinning of the domain walls, but domain growth remained the governing process of the domain switching behavior. The intriguing asymmetric domain switching and related domain wall pinning behavior in the fatigued BiFeO3 capacitors may be attributed to the formation of a defect layer near the interface between the ferroelectric film and electrode.