ABSTRACT Two‐dimensional (2D) van der Waals (vdW) magnets offer a versatile platform to explore fundamental physics and low‐dimensional functionalities. Metal thiophosphates (MTPs) with mobile Cu + ions exhibit a ferroionic state, where polarization arises from ionic redistribution among multiple nearly degenerate sites. CuVP 2 S 6 uniquely combines intrinsic ferromagnetism from the V sublattice with Cu + ‐driven ferroionic configurational freedom, enabling direct exploration of how ionic dynamics influence magnetic interactions. Herein, high‐quality CuVP 2 S 6 single crystals are synthesized, and their structural and physical properties are systematically investigated. Temperature‐dependent neutron diffraction elucidates a ferroionic structure with dynamic distributions of copper ions across multiple crystallographic sites. The versatile occupations are driven by local symmetry‐controlled orbital interactions between copper ions and surrounding ligands through a second‐order Jahn–Teller mechanism. Magnetic measurements identify a ferromagnetic (FM) transition below 3.3 K. The pressure‐controlled magnetocrystalline anisotropy and interlayer exchange interactions mediated by Cu + migration are demonstrated, boosting the Curie temperature remarkably by over 60% and inducing a soft‐to‐hard FM transition unparalleled within the MTP family. These results demonstrate that ionic configurational freedom provides an efficient route to control magnetism, opening new possibilities for spintronic applications.
Xie et al. (2026) studied this question.