Strong interaction between ferroelectric polarization and oxygen vacancy in BiFeO3 thin film capacitors

Influence of oxygen vacancy (V-O(center dot center dot)) distribution on the polarization properties of SrRuO3(SRO)/BiFeO3(BFO)/SRO capacitors was investigated. Our thin-film experiments and density function theory (DFT) calculations reveal that a strong attractive interaction between V-O(center dot center dot) and the bottom BFO/SRO interface gives rise to an V-O(center dot center dot)-rich defective layer for as-deposited capacitors. The distribution with the V-O(center dot center dot)-rich layer is gradually broken by an electrical training and finally becomes symmetric, leading to a polarization-hysteresis change from a markedly rounded to a typical ferroelectric loop. This study demonstrates that defect engineering utilizing V-O(center dot center dot) is an effective approach to control the polarization-related properties of BFO in capacitor form. (C)2016 The Ceramic Society of Japan. All rights reserved.