Spin–Phonon Coupling and Magnetic Ordering in Layered CrPS ₄

Magnetism in van der Waals (vdW) materials offers a platform for exploring dimensionality-tuned magnetic ordering and distinct spin-phonon coupling. Among such materials, CrPS₄ stands out as an air-stable A-type antiferromagnet with a Néel temperature of 36 K. Here, we investigate the evolution of phonon modes influenced by magnetic ordering in CrPS₄ across varying temperatures and layer thicknesses by using Raman spectroscopy, supported by theoretical calculations. Due to weak interlayer coupling, the thickness-dependent changes in phonon frequencies are negligible (<0.5 cm^-1). Notably, anomalous temperature-dependent behavior of the nominally non-magnetic P-S rocking mode reveals its coupling to Cr-S-Cr super-exchange pathways, indicating a strong spin-phonon interaction in CrPS₄. The observed magnetic order and spin-phonon interactions remain robust across different thicknesses, with coupling strengths comparable to those of other vdW magnets. Magneto-crystalline anisotropy, metamagnetic transitions, and strong spin-phonon coupling highlight CrPS₄ as a promising candidate for integration into vdW heterostructures, offering potential for next-generation magnetic device applications.