Large-Scale Domain Engineering in Two-Dimensional Ferroelectric CuInP2S6 via Giant Flexoelectric Effect

Chen Chen; Heng Liu; Qinglin Lai; Xiaoyu Mao; Jun Fu; Zhaoming Fu; Hualing Zeng

doi:10.1021/acs.nanolett.2c00130

Large-Scale Domain Engineering in Two-Dimensional Ferroelectric CuInP₂S₆ via Giant Flexoelectric Effect

Nano Lett. 2022 Apr 27;22(8):3275-3282. doi: 10.1021/acs.nanolett.2c00130. Epub 2022 Apr 12.

Authors

Chen Chen^{1

2}, Heng Liu^{1

2}, Qinglin Lai^{1

2}, Xiaoyu Mao^{1

2}, Jun Fu^{1

2}, Zhaoming Fu^{3

4}, Hualing Zeng^{1

2}

Affiliations

¹ International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
² Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
³ College of Physics and Electronic Information, Yunnan Normal University, Kunming 650500, China.
⁴ Yunnan Key Laboratory of Optoelectronic Information Technology, Kunming 650500, China.

PMID: 35412313
DOI: 10.1021/acs.nanolett.2c00130

Abstract

Room-temperature ferroelectricity in two-dimensional (2D) materials is a potential for developing atomic-scale functional devices. However, as a key step for the technology implementations of 2D ferroelectrics in electronics, the controllable generation of uniform domains remains challenging at the current stage because domain engineering through an external electric field at the 2D limit inevitably leads to large leakage currents and material breakdown. Here, we demonstrate a voltage-free method, the flexoelectric effect, to artificially generate large-scale stripe domains in 2D ferroelectric CuInP₂S₆ with single domain lateral size at the scale of several hundred microns. With giant strain gradients (∼10⁶ m^-1), we mechanically switch the out-of-plane polarization in ultrathin CuInP₂S₆. The flexoelectric control of polarization is understood with a distorted Landau-Ginzburg-Devonshire double well model. Through substrate strain engineering, the stripe domain density is controllable. Our results highlight the potential of developing van der Waals ferroelectrics-based flexible electronics.

Keywords: 2D ferroelectrics; CuInP2S6; artificial domains; flexoelectricity; polarization.