Evolution of antiferroelectricity and magnetism in van der Waal multiferroic CuCrP₂S₆

2D van der Waal multiferroic material has recently been extensively investigated as promising building blocks for next-generation nonvolatile memory devices. Among them, CuCrP₂S₆ (CCPS) stands out owing to its coexistence of antiferromagnetism and robust antiferroelectricity that leads to high thermal stability in the CCPS-based devices. A long-standing question is the nature of the preceding antipolar state of Cu⁺, initially considered disordered, and the role it takes in stabilizing the antiferroelectric state of Cu⁺. In this regard, a detailed X-ray and neutron study could help shed light on this question. Through combined X-ray and neutron study on single crystal CCPS, we have observed a systematic temperature-driven structural evolution suggesting incommensurate supercell modulation of the Cu⁺ sublattice that eventually evolves into the antiferroelectric state. Low temperature neutron measurements under magnetic field reveal spin reorientations in the Cr³⁺ sublattice that are correlated with the magnetoelectric coupling behaviors. Findings in the present study not only help elucidate the stabilizing mechanism of antiferroelectricity in CCPS, but also provide insights on the magnetoelectric coupling in this system, thus paves the way for further advanced research on CCPS-based memory devices.