Atomistic Mechanisms of the Crystallographic Orientation-Dependent Cu<sub>1.8</sub>S Conductive Channel Formation in Cu<sub>2</sub>S-Based Memristors.

Li, Xing; Yan, Weiwei; Wang, Dongyang; Huang, Wentao; Guo, Ying; Gu, Lin; Cheng, Shaobo; Shan, Chongxin et al. · Adv Mater · 2025

basic_science · Level V

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Abstract

Achieving multiple types of resistive switching in a single material with controlled ionic motion is a key challenge in neuromorphic computing, traditionally addressed by combining materials with distinct switching behaviors. Here, Cu<sub>2-x</sub>S is identified as a promising candidate to overcome this limitation due to its hierarchical phase transitions. Using in situ biasing experiments, reversible and non-reversible phase transitions (and resistive switching) are demonstrated in γ-Cu<sub>2</sub>S by controlling the compliance current. The formation of parallel high-digenite Cu<sub>1.8</sub>S channels, orientated along the γ-Cu<sub>2</sub>S [201] crystallographic direction, drives the nonvolatile resistive switching. These channels emerge via an intermediate δ-Cu<sub>2</sub>S phase and are stabilized at room temperature by residual strains, alongside β-Cu<sub>2</sub>S phase. The work clarifies the complex, electrically triggered phase transformations in γ-Cu<sub>2</sub>S, and highlights the potential of Cu<sub>2-x</sub>S as a versatile material for neuromorphic computing.