High-<i>T</i><sub>C</sub> Two-Dimensional Ferroelectric CuCrS<sub>2</sub> Grown <i>via</i> Chemical Vapor Deposition.

Xu, Xiang; Zhong, Tingting; Zuo, Nian; Li, Zexin; Li, Dongyan; Pi, Lejing; Chen, Ping; Wu, Menghao et al. · ACS Nano · 2022

basic_science · Level V

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Abstract

Two-dimensional (2D) ferroelectrics have attracted intensive attention. However, the 2D ferroelectrics remain rare, and especially few of them represent high ferroelectric transition temperature (<i>T</i><sub>C</sub>), which is important for the usability of ferroelectrics. Herein, CuCrS<sub>2</sub> nanoflakes are synthesized by salt-assisted chemical vapor deposition and exhibit switchable ferroelectric polarization even when the thickness is downscaled to 6 nm. On the contrary, a CuCrS<sub>2</sub> nanoflake shows a <i>T</i><sub>C</sub> as high as ∼700 K, which can be attributed to the robust tetrahedral bonding configurations of Cu cations. Such robustness can be further clarified by a theoretically predicted high order-disorder transition barrier and structure evolution from 600 to 800 K. Additionally, the interlocked out-of-plane (OOP) and in-plane (IP) ferroelectric domains are observed and two kinds of devices based on OOP and IP polarizations are demonstrated.