Probing the antiferroelectric ordering in atomically thin CuCrP2S6 by Raman spectroscopy

Two-dimensional multiferroic materials, which exhibit interesting phenomena such as magnetism and ferroelectricity, have been proposed for use in next-generation nanoscale devices and sensors. However, studies to date have been mostly limited to the ferroelectricity driven by external electric field in few-layer CuCrP2S6. Here, we investigate on the observation of spontaneous antiferromagnetic ordering in the two-dimensional limit. By monitoring the Raman peaks down to monolayer arising from the off-centering displacement of Cu+ ions owing to antiferroelectric ordering at the transition temperature, we demonstrate that CuCrP2S6 exhibits antiferroelectric ordering down to the trilayer limit. Its Curie temperature of about 50 K in trilayer is much lower than 155 K of the bulk crystal, indicating that interlayer interaction has a strong effect on antiferroelectric ordering. Our studies highlight the intriguing antiferroelectric properties in two-dimensional limit and suggest that CuCrP2S6 is a promising candidate material for future multiferroic applications.