Effect of Cu-driven symmetry breaking on local phosphorus fields across phase transitions in CuCrP2S6

Determine how symmetry breaking arising from Cu+ ion displacements and the evolution of magnetic correlations across the quasi-antiferroelectric, antiferroelectric, and antiferromagnetic transitions in CuCrP2S6 modify the local electronic and magnetic fields at the 31P sites within the [P2S6]4− units.

Background

CuCrP2S6 is a layered van der Waals magnet that exhibits a sequence of structural and magnetic transitions upon cooling: a high-temperature paraelectric state, a quasi-antiferroelectric regime near 185 K, long-range antiferroelectric order below about 150 K, and A-type antiferromagnetic order below roughly 30 K. The Cu+ sublattice undergoes antipolar displacements in the antiferroelectric phase, reducing crystal symmetry and potentially altering local environments of ligand nuclei such as phosphorus.

While bulk and spectroscopic studies have established this sequence of transitions, a fully microscopic picture linking Cu-driven symmetry breaking and developing magnetic correlations to the local hyperfine fields and electronic environment at the phosphorus sites had not been clearly established. Clarifying this relationship is essential for understanding how electric-dipole order couples to magnetic degrees of freedom in thiophosphate van der Waals magnets.

References

Despite extensive bulk and spectroscopic studies, a microscopic understanding of how the local magnetic and structural environments evolve across the QAFE, AFE, and AFM transitions remains incomplete. It is not yet clear how the symmetry breaking associated with Cu displacements and the development of magnetic correlations modify the local electronic and magnetic fields at the phosphorus sites.

— Microscopic NMR evidence for successive antiferroelectric and antiferromagnetic order in the van der Waals magnet CuCrP$_2$S$_6$  (2604.02898 - Saramgi et al., 3 Apr 2026) in Section I. Introduction