Dynamics of ferroelectricity in monolayer AgCr2S4 calculated with a machine learning potential

JM Wu and HR Zhu and XY Li and GL Yu and HY Yu and CS Xu, PHYSICAL REVIEW B, 111, 085417 (2025).

DOI: 10.1103/PhysRevB.111.085417

Ferroelectric materials hold significant potential for high-density nonvolatile memory applications. Understanding the dynamic mechanism of ferroelectricity is crucial for maximizing the utilization of these materials. In this study, we investigate the ferroelectric properties of monolayer AgCr2S4 by combining density functional theory (DFT) calculations with molecular dynamics (MD) simulations that utilize machine learning potentials. Our investigation reveals that the off- center displacement of Ag ions primarily drives the ferroelectricity in monolayer AgCr2S4. Remarkably, the system exhibits a high ferroelectric- paraelectric phase transition temperature of 600 K. Under low temperatures, a distinctive domain structure emerges, characterized by domain walls that induce silver vacancy defects and interstitial atoms. Moreover, ferroelectric hysteresis loops indicate that the out-of-plane and in-plane polarizations of the AgCr2S4 monolayer are switchable by applying an external electric field. Thus, our findings suggest that monolayer AgCr2S4 retains ferroelectricity at room temperature, highlighting its promising potential for applications in ferroelectric devices.

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