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

doi:10.1038/s41467-022-32519-2

Enhanced polarization and abnormal flexural deformation in bent freestanding perovskite oxides

Nat Commun. 2022 Aug 31;13(1):5116. doi: 10.1038/s41467-022-32519-2.

Authors

Songhua Cai^#¹, Yingzhuo Lun^#², Dianxiang Ji^#³, Peng Lv², Lu Han⁴, Changqing Guo², Yipeng Zang⁴, Si Gao⁴, Yifan Wei⁴, Min Gu⁴, Chunchen Zhang⁴, Zhengbin Gu⁴, Xueyun Wang², Christopher Addiego⁵, Daining Fang^{6

7}, Yuefeng Nie⁸, Jiawang Hong⁹, Peng Wang¹⁰, Xiaoqing Pan^{11

12

13}

Affiliations

¹ Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, 999077, Hong Kong. songhua.cai@polyu.edu.hk.
² School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China.
³ Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, 999077, Hong Kong.
⁴ National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
⁵ Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA.
⁶ Institute of Advanced Structure Technology, Beijing Institute of Technology, Beijing, 100081, China.
⁷ State Key Laboratory for Turbulence and Complex Systems & Center for Applied Physics and Technology, College of Engineering, Peking University, Beijing, 100871, China.
⁸ National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China. ynie@nju.edu.cn.
⁹ School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China. hongjw@bit.edu.cn.
¹⁰ Department of Physics, University of Warwick, Coventry, CV4 7AL, UK. peng.wang.3@warwick.ac.uk.
¹¹ Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA. xiaoqing.pan@uci.edu.
¹² Department of Materials Science and Engineering, University of California, Irvine, CA, 92697, USA. xiaoqing.pan@uci.edu.
¹³ Irvine Materials Research Institute, University of California, Irvine, CA, 92697, USA. xiaoqing.pan@uci.edu.

^# Contributed equally.

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.

Abstract

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