  Nickel phosphorus trisulfide (NiPS3), a van der Waals (vdW) 2D
antiferromagnet, has captivated enormous attention for its intriguing physics
in recent years. However, despite its fundamental importance in physics of
magnetism and promising potential for technological applications, the study of
magnetic domains in NiPS3 down to atomically thin is still lacking. Here, we
report the layer-dependent magnetic characteristics and magnetic domains within
antiferromagnetic NiPS3 by employing linear dichroism (LD) combined with
polarized microscopy, spin-correlated photoluminescence (PL), and Raman
spectroscopy. Our results reveal the existence of the
paramagnetic-to-antiferromagnetic phase transition in bulk to bilayer NiPS3
with stronger spin fluctuation in thinner NiPS3. Furthermore, our study
identifies three distinct antiferromagnetic domains within atomicallythin NiPS3
and captures the thermally-activated domain evolution. Our findings provide
crucial insights for the development of antiferromagnetic spintronics and
related technologies.
