Copper Chromium Thiophosphate (CuCrP₂S₆)

CuCrP₂S₆ is a two-dimensional van der Waals material of considerable interest within the transition metal thiophosphate family, possessing both antiferroelectric and magnetic order parameters, making it a representative system for two-dimensional multiferroic research. It adopts a monoclinic structure, with space group C2/c at room temperature (C2/m in the high-temperature phase); within each layer, Cu, Cr, and P–P dimers alternately occupy octahedral vacancies. The Cu ions displace off-center, shifting up or down, forming a switchable electric polarization that gives rise to ferroelectric/antiferroelectric behavior, while the Cr³⁺ ions contribute spin and produce antiferromagnetic order with a Néel temperature of about 32 K. Because electric polarization and magnetism coexist and couple, CuCrP₂S₆ holds unique value for magnetoelectric coupling, nonvolatile memory, and two-dimensional multiferroic devices.