Depth resolved lattice-charge coupling in epitaxial BiFeO3 thin film

作者：Lee Hyeon Jun; Lee Sung Su; Kwak Jeong Hun; Kim Young Min; Jeong Hu Young; Borisevich Albina Y; Lee Su Yong; Noh Do Young; Kwon Owoong; Kim Yunseok; Jo Ji Young^*

来源：Scientific Reports, 2016, 6(1): 38724.

DOI：10.1038/srep38724

For epitaxial films, a critical thickness (t(c)) can create a phenomenological interface between a strained bottom layer and a relaxed top layer. Here, we present an experimental report of how the t(c) in BiFeO3 thin films acts as a boundary to determine the crystalline phase, ferroelectricity, and piezoelectricity in 60 nm thick BiFeO3/SrRuO3/SrTiO3 substrate. We found larger Fe cation displacement of the relaxed layer than that of strained layer. In the time-resolved X-ray microdiffraction analyses, the piezoelectric response of the BiFeO3 film was resolved into a strained layer with an extremely low piezoelectric coefficient of 2.4 pm/V and a relaxed layer with a piezoelectric coefficient of 32 pm/V. The difference in the Fe displacements between the strained and relaxed layers is in good agreement with the differences in the piezoelectric coefficient due to the electromechanical coupling.

• 出版日期2016-12-8