Reversible flexoelectric domain engineering at the nanoscale in van der Waals ferroelectrics

Heng Liu; Qinglin Lai; Jun Fu; Shijie Zhang; Zhaoming Fu; Hualing Zeng

doi:10.1038/s41467-024-48892-z

Reversible flexoelectric domain engineering at the nanoscale in van der Waals ferroelectrics

Nat Commun. 2024 May 29;15(1):4556. doi: 10.1038/s41467-024-48892-z.

Authors

Heng Liu^#^{1

2

3}, Qinglin Lai^#^{1

2

3}, Jun Fu^{1

2

3}, Shijie Zhang^{4

5}, Zhaoming Fu^{4

5}, Hualing Zeng^{6

7

8}

Affiliations

¹ International Center for Quantum Design of Functional Materials (ICQD), Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, China.
² CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China.
³ Hefei National Laboratory, University of Science and Technology of China, Hefei, 230088, China.
⁴ College of Physics and Electronic Information, Yunnan Normal University, Kunming, 650500, China.
⁵ Yunnan Key Laboratory of Opto-Electronic Information Technology, Kunming, 650500, China.
⁶ International Center for Quantum Design of Functional Materials (ICQD), Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, China. hlzeng@ustc.edu.cn.
⁷ CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China. hlzeng@ustc.edu.cn.
⁸ Hefei National Laboratory, University of Science and Technology of China, Hefei, 230088, China. hlzeng@ustc.edu.cn.

^# Contributed equally.

Abstract

The universal flexoelectric effect in solids provides a mechanical pathway for controlling electric polarization in ultrathin ferroelectrics, eliminating potential material breakdown from a giant electric field at the nanoscale. One challenge of this approach is arbitrary implementation, which is strongly hindered by one-way switching capability. Here, utilizing the innate flexibility of van der Waals materials, we demonstrate that ferroelectric polarization and domain structures can be mechanically, reversibly, and arbitrarily switched in two-dimensional CuInP₂S₆ via the nano-tip imprinting technique. The bidirectional flexoelectric control is attributed to the extended tip-induced deformation in two-dimensional systems with innate flexibility at the atomic scale. By employing an elastic substrate, artificial ferroelectric nanodomains with lateral sizes as small as ~80 nm are noninvasively generated in an area of 1 μm², equal to a density of 31.4 Gbit/in². Our results highlight the potential applications of van der Waals ferroelectrics in data storage and flexoelectronics.