Anomalies in the thermal conductivity of honeycomb antiferromagnet MnPS₃
Pith reviewed 2026-05-20 10:06 UTC · model grok-4.3
The pith
In MnPS3, thermal Hall conductivity shows sign reversals below 2 K inside the spin-flop phase due to magnon Berry curvature redistribution.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Below 2 K, 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. These anomalies are caused by the redistribution of Berry curvature in magnon bands.
What carries the argument
Redistribution of Berry curvature in magnon bands, which alters the topological contributions to thermal transport under applied magnetic fields.
If this is right
- Thermal Hall effect measurements can detect subtle changes in magnon band topology in magnetic insulators.
- Sign reversals in thermal Hall conductivity indicate field-induced shifts in Berry curvature distribution.
- Multiple valleys in longitudinal thermal conductivity correlate with the same magnon band changes.
- Such anomalies are observable only at very low temperatures where magnon contributions dominate over phonons.
Where Pith is reading between the lines
- This approach could be applied to other two-dimensional antiferromagnets to map their magnon topology.
- Understanding these redistributions may help design materials with tailored thermal Hall responses for spintronic applications.
- Explicit calculations of magnon bands in MnPS3 under field could confirm the curvature changes responsible for the sign flips.
Load-bearing premise
The low-temperature anomalies stem mainly from magnon Berry curvature redistribution instead of phonon effects or experimental issues.
What would settle it
Direct computation of the magnon Berry curvature as a function of magnetic field in the spin-flop phase to check if it predicts the observed sign reversal points.
read the original abstract
Intrinsic two-dimensional magnets serve as a good platform to explore collective, charge-neutral and low-energy excitations. Distinguishing the crucial role of them in experimental aspect remains a challenge for decades. Here, we study the thermal transport in honeycomb antiferromagnet MnPS$_{3}$ with $T_N$=78 K down to very low temperatures (<0.01$T_N$). At high temperatures (>0.1$T_N$), 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.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript reports thermal transport measurements on the honeycomb antiferromagnet MnPS₃ (T_N = 78 K) down to T < 0.01 T_N. It reproduces prior observations of a linear phonon Hall effect and a feature at the spin-flop transition for T > 0.1 T_N. Below 2 K, within the spin-flop phase, the field dependence of the thermal Hall conductivity κ_xy exhibits sign reversals while the longitudinal thermal conductivity κ_xx shows multiple valleys; the authors suggest these anomalies arise from field-induced redistribution of Berry curvature in the magnon bands.
Significance. The low-temperature data set extends prior work and supplies clear experimental signatures of field-dependent anomalies in both κ_xy and κ_xx. If the magnon-Berry-curvature interpretation can be placed on a quantitative footing, the results would illustrate the sensitivity of thermal Hall measurements to topological features of magnon spectra in insulating magnets.
major comments (1)
- [Discussion of low-T anomalies] The central interpretation—that the sign reversals in κ_xy(H) and the multiple valleys in κ_xx(H) below 2 K are caused by redistribution of Berry curvature in magnon bands—is presented without supporting linear spin-wave calculations, field-dependent magnon dispersions, or explicit Berry-curvature integrals for the spin-flop phase. This inference from temperature and field sweeps alone leaves open alternative explanations (field-dependent phonon scattering, residual phonon Hall contributions, or magnon-phonon hybridization) that are not quantitatively excluded.
minor comments (1)
- [Abstract] The abstract uses the shorthand 0.1 T_N and <0.01 T_N without stating the numerical value of T_N (given as 78 K in the main text); inserting the explicit temperature scales would aid immediate readability.
Simulated Author's Rebuttal
We thank the referee for their positive assessment of the significance of our low-temperature data and for the constructive feedback on the interpretation. We address the major comment below.
read point-by-point responses
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Referee: [Discussion of low-T anomalies] The central interpretation—that the sign reversals in κ_xy(H) and the multiple valleys in κ_xx(H) below 2 K are caused by redistribution of Berry curvature in magnon bands—is presented without supporting linear spin-wave calculations, field-dependent magnon dispersions, or explicit Berry-curvature integrals for the spin-flop phase. This inference from temperature and field sweeps alone leaves open alternative explanations (field-dependent phonon scattering, residual phonon Hall contributions, or magnon-phonon hybridization) that are not quantitatively excluded.
Authors: We agree that the manuscript presents the interpretation as a suggestion based on the experimental observations rather than on explicit calculations. The anomalies are observed exclusively below 2 K (i.e., <0.03 T_N) and only inside the spin-flop phase, a regime in which magnon excitations are expected to dominate the thermal transport while phonon contributions become comparatively featureless. The multiple valleys in κ_xx(H) and the accompanying sign changes in κ_xy(H) are consistent with field-induced modifications to the magnon band structure. Nevertheless, we acknowledge that quantitative linear spin-wave calculations, field-dependent dispersions, and Berry-curvature integrals for the spin-flop phase are not provided, leaving alternative mechanisms such as field-dependent phonon scattering or magnon-phonon hybridization unexcluded at a quantitative level. In the revised manuscript we will expand the discussion to include a more detailed qualitative argument based on the expected magnon spectrum in the canted state, to state the limitations of the present interpretation explicitly, and to outline the type of theoretical work that would be required to place the Berry-curvature scenario on a firmer footing. revision: partial
Circularity Check
No circularity: experimental anomalies interpreted via field/T dependence without reduction to fitted inputs or self-citations
full rationale
The manuscript presents direct low-temperature measurements of longitudinal and Hall thermal conductivities in MnPS3, documenting sign reversals in κ_xy(H) and multiple valleys in κ_xx(H) below 2 K inside the spin-flop phase. These features are contrasted with high-T behavior that reproduces an external prior report. The attribution to magnon Berry curvature redistribution is offered as a qualitative suggestion based on the observed T and H dependence, not as a mathematical derivation whose equations reduce to the data by construction. No parameters are fitted to a subset and then relabeled as predictions, no self-citation chain is invoked to justify uniqueness or an ansatz, and the central claim does not collapse into a renaming of known results. The analysis remains grounded in independent experimental observations.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Strong spin-lattice coupling produces a spin-flop transition whose signature appears in thermal transport.
Reference graph
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discussion (0)
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