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Published on: February 27, 2017
Enhanced polarization and abnormal flexural deformation in bent freestanding perovskite oxides
Songhua Cai1, Yingzhuo Lun2, Dianxiang Ji3
1Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, 999077, Hong Kong. songhua.cai@polyu.edu.hk.
Abstract:
Recent realizations of ultrathin freestanding perovskite oxides offer a unique platform to probe novel properties in two-dimensional oxides. Here, we observe a giant flexoelectric response in freestanding BiFeO3 and SrTiO3 in their bent state arising from strain gradients up to 3.5 × 107 m-1, suggesting a promising approach for realizing ultra-large polarizations. Additionally, a substantial change in membrane thickness is discovered in bent freestanding BiFeO3, which implies an unusual bending-expansion/shrinkage effect in the ferroelectric membrane that has never been seen before in crystalline materials. Our theoretical model reveals that this unprecedented flexural deformation within the membrane is attributable to a flexoelectricity-piezoelectricity interplay. The finding unveils intriguing nanoscale electromechanical properties and provides guidance for their practical applications in flexible nanoelectromechanical systems.
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