Observation of Three-State Nematicity and Domain Evolution in Atomically Thin Antiferromagnetic NiPS.

Nickel phosphorus trisulfide (NiPS), a van der Waals 2D antiferromagnet, has received significant interest for its intriguing properties in recent years. However, despite its fundamental importance in the physics of low-dimensional magnetism and promising potential for technological applications, the study of magnetic domains in NiPS down to an atomically thin state is still lacking. Here, we report the layer-dependent magnetic characteristics and magnetic domains in NiPS by employing linear dichroism spectroscopy, polarized microscopy, spin-correlated photoluminescence, and Raman spectroscopy. Our results reveal the existence of the paramagnetic-to-antiferromagnetic phase transition in bulk to bilayer NiPS and provide evidence of the role of stronger spin fluctuations in thin NiPS. Furthermore, our study identifies three distinct antiferromagnetic domains within atomically thin NiPS and captures the thermally activated domain evolution. Our findings provide crucial insights for the development of antiferromagnetic spintronics and related technologies.