Intrinsic two-dimensional magnets serve as a good platform to explore collective, charge-neutral, and low-energy excitations. Distinguishing their crucial role in the experimental aspect remains a challenge for decades. Here, we study the thermal transport in honeycomb antiferromagnet ${\mathrm{MnPS}}_3$ with $T_{\mathrm{N}}=78$ K down to very low temperatures ($<0.01T_{\mathrm{N}}$). At high temperatures ($>0.1T_{\mathrm{N}}$), the field dependence of the thermal Hall conductivity exhibits a linear phonon Hall effect and a peak associated with the spin-flop transition due to a strong spin-lattice coupling, well reproducing the previous report [Phys. Rev. B 110, 165147 (2024)]. Notably, below 2 K, we find that the field dependence of the thermal Hall conductivity exhibits sign reversals within the spin-flop phase, at which the field dependence of the longitudinal thermal conductivity also shows multiple valleys. We suggest that these anomalies are caused by the redistribution of Berry curvature in magnon bands, demonstrating the superior performance of the thermal Hall measurements to detect the Berry curvature distributions in magnetic insulators.

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• Berry curvature
• Magnetic susceptibility
• Magnons
• Spin-phonon coupling
• Thermal Hall effect
• Thermal conductivity
• Antiferromagnets