We investigate the thermodynamic properties of the anisotropic magnetocaloric effect, specific heat, and spin-phonon coupling in single-crystalline van der Waals antiferromagnet $\mathrm{FeP}{\mathrm{S}}_3$, focusing on the second-order antiferromagnetic to paramagnetic phase transition near the Neel temperature $T_{\mathrm{N}}\sim 119\mathrm{K}$. A sharp λ-type anomaly in the heat capacity confirms the continuous nature of the transition, thereby ensuring that the magnetic entropy change ($\mathrm{\Delta }{S}_M$) can be reliably derived from magnetization measurements via the Maxwell relation. Owing to the strong uniaxial anisotropy, $\mathrm{\Delta }{S}_M$ is strongly orientation dependent and reaches up to 4.2 $\mathrm{J}\mathrm{k}{\mathrm{g}}^{-1}{\mathrm{K}}^{-1}$ for magnetic fields applied along the $c$ axis at 6 T, while isothermal magnetization measurements reveal significant differences between the $c$-axis and $ab$-plane responses, approaching $\sim 2.32\mathrm{J}\mathrm{k}{\mathrm{g}}^{-1}{\mathrm{K}}^{-1}$ at 5 T. A universal scaling analysis of $\mathrm{\Delta }{S}_M$ further supports the second-order nature of the magnetic phase transition. Strong interactions between the spin and lattice degrees of freedom are suggested by complementary Raman spectroscopic studies that show distinct signs of spin-phonon coupling, including phonon softening in the magnetically ordered phase. These results highlight the magnetocaloric effect as a thermodynamic probe of entropy-driven lattice dynamics in two-dimensional Ising-type antiferromagnets and show that it functions as a thermodynamic probe of spin-lattice coupling in $\mathrm{FeP}{\mathrm{S}}_3$.

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• Magnetic coupling
• Magnetic interactions
• Magnetocaloric effect
• Spintronics
• Antiferromagnets
• Magnetic refrigeration
• Single crystal materials
• van der Waals systems
• High-resolution transmission electron microscopy
• Magnetization measurements
• Specific heat measurements