Anisotropic Quasi-particle Decay Dynamics in Antiferromagnetic CuCrP₂S₆ Single Crystals

Two-dimensional van der Waals material CuCrP₂S₆ (CCPS) has attracted significant attention for its coexistence of antiferromagnetic and antiferroelectric states, which have been reported to give rise to strong optical anisotropy. Here, we investigate its anisotropic quasi-particle decay dynamics using polarization-resolved femtosecond transient optical spectroscopy. We observe that the quasi-particle decay dynamics in the CCPS single crystal strongly correlate with its spin ordering. The quasi-particle decay via phonon-phonon coupling of CCPS exhibits strong in-plane anisotropy at the antiferromagnetic phase, while such anisotropy almost disappears at the paramagnetic phase. The lattice heating process and lattice cooling process also show anisotropy at the antiferromagnetic phase CCPS due to the spin ordering. Our work enriches the fundamental understanding of the role of antiferromagnetic ordering on the quasi-particle decay dynamics in two-dimensional magnetic materials.