Dual-role ion dynamics in ferroionic CuInP2S6: revealing the transition from ferroelectric to ionic switching mechanisms

Xingan Jiang; Xiangping Zhang; Zunyi Deng; Jianming Deng; Xiaolei Wang; Xueyun Wang; Weiyou Yang

doi:10.1038/s41467-024-55160-7

Dual-role ion dynamics in ferroionic CuInP₂S₆: revealing the transition from ferroelectric to ionic switching mechanisms

Nat Commun. 2024 Dec 30;15(1):10822. doi: 10.1038/s41467-024-55160-7.

Authors

Xingan Jiang^#¹, Xiangping Zhang^#², Zunyi Deng^#³, Jianming Deng⁴, Xiaolei Wang⁵, Xueyun Wang⁶, Weiyou Yang⁷

Affiliations

¹ Institute of Micro/Nano Materials and Devices, Ningbo University of Technology, Ningbo, China.
² Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.
³ School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China.
⁴ Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices, Huizhou University, Huizhou, Guangdong, China.
⁵ School of Physics and Optoelectronic Engineering, Beijing University of Technology, Beijing, China. xiaoleiwang@bjut.edu.cn.
⁶ School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China. xueyun@bit.edu.cn.
⁷ Institute of Micro/Nano Materials and Devices, Ningbo University of Technology, Ningbo, China. weiyouyang@tsinghua.org.cn.

^# Contributed equally.

Abstract

Due to its "ferroionic" nature, CuInP₂S₆ combines switchable ferroelectric polarization with highly mobile Cu ions, allowing for multiple resistance states. Its conductive mechanism involves ferroelectric switching, ion migration, and corresponding intercoupling, which are highly sensitive to external electric field. Distinguishing the dominant contribution of either ferroelectric switching or ion migration to dynamic conductivity remains a challenge and the conductive mechanism is not clear yet. Here, based on polarization switching analyses and first-principles calculations, this work demonstrates that the Cu ion migration pathways enable the formation of a quadruple-well state, determining the conductive mechanism. Accordingly, it favors the manipulation of Cu ion transport in the intralayer and interlayer in a controlled manner, and makes a transition from ferroelectric-dominated to ion-migration-dominated conductivity, by tailoring the electric fields. This work deepens the understanding of ion migration dynamics and conductive switching in ferroionic systems, which is critical for the advancement of memristor-based neuromorphic computing.

Abstract

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