Six-state clock physics observed in atomically thin NiPS3
Mar 10th 2026
New experiments on monolayer NiPS3 report discrete sixfold magnetic anisotropy and real-space signatures of the six-state clock model, giving direct evidence of topological defects and a critical intermediate phase in an atomically thin antiferromagnet.
- Researchers imaged six discrete Néel vector orientations separated by 60 degrees in monolayer NiPS3 using optical second harmonic generation and real-space microscopy.
- Temperature-dependent measurements show signatures consistent with two distinct crossovers and an intermediate critical regime predicted by the six-state clock model and Berezinskii-Kosterlitz-Thouless type physics.
- Real-space maps reveal domain walls and vortexlike topological defects that match expectations for a q = 6 clock system in two dimensions.
- The results help reconcile earlier reports of three-state nematicity and XY-like behavior by showing a lattice-driven sixfold anisotropy that pins magnetic directions at low temperature.
- This work strengthens the link between ideal statistical models and real van der Waals magnets and points to new ways to control ultrathin antiferromagnets for spintronic applications