Enhanced polarization and abnormal flexural deformation in bent freestanding perovskite oxides
Songhua Cai, Yingzhuo Lun, Dianxiang Ji, Peng Lv, Lu Han, Changqing Guo, Yipeng Zang, Si Gao, Yifan Wei, Min Gu, Chunchen Zhang, Zhengbin Gu, Xueyun Wang, Christopher Addiego, Daining Fang, Yuefeng Nie, Jiawang Hong, Peng Wang, Xiaoqing Pan
Abstract
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 BiFeO 3 and SrTiO 3 in their bent state arising from strain gradients up to 3.5 × 10 7 m −1 , suggesting a promising approach for realizing ultra-large polarizations. Additionally, a substantial change in membrane thickness is discovered in bent freestanding BiFeO 3 , 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.