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arxiv: 2508.19248 · v4 · pith:QMNKMKCVnew · submitted 2025-08-26 · ❄️ cond-mat.str-el · cond-mat.mtrl-sci

Disorder-induced proximate quantum spin ice phase in Pr2Sn2O7

Yi Luo , Brenden R. Ortiz , Miles Knudtson , Stephen D. Wilson , Jue Liu , Benjamin A. Frandsen , Si Athena Chen , Matthias D. Frontzek
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Andrey A. Podlesnyak Joseph A. M. Paddison Adam A. Aczel
This is my paper

Pith reviewed 2026-05-18 20:36 UTC · model grok-4.3

classification ❄️ cond-mat.str-el cond-mat.mtrl-sci
keywords quantum spin icepyrochloredisorderspin freezingPr2Sn2O7non-Kramers ionsneutron scatteringground state
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The pith

In Pr2Sn2O7, disorder induces spin freezing at 0.15 K while quantum spin-ice correlations persist down to low temperatures.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper examines the non-Kramers pyrochlore Pr2Sn2O7 through bulk measurements and neutron scattering. Below about 1 K the material displays anisotropic spin-ice correlations and two separate dynamical timescales, signatures associated with quantum spin-ice physics. Upon cooling further the system undergoes a complete spin-freezing transition at 0.15 K, at which point the nuclear Schottky anomaly recovers fully, a gapped magnetic excitation appears, and weak (100) magnetic correlations develop. Placing the compound near the spin-frozen edge of a disorder-perturbed phase diagram through comparison with other Pr-based pyrochlores leads to the conclusion that structural disorder can drive the evolution from quantum spin-ice behavior into a frozen state while the system remains close to a quantum spin liquid.

Core claim

The central claim is that in the non-Kramers pyrochlore Pr2Sn2O7, structural disorder produces a proximate quantum spin-ice phase in which hallmark quantum spin-ice correlations and dynamics coexist with a disorder-induced spin-freezing transition at 0.15 K and the recovery of a full nuclear Schottky anomaly.

What carries the argument

The disorder-perturbed phase diagram for non-Kramers pyrochlores, which positions Pr2Sn2O7 near the spin-frozen boundary while still allowing quantum spin-ice correlations to survive.

If this is right

  • Quantum spin-ice behavior can evolve into frozen ground states through the action of structural disorder.
  • Proximity to a quantum spin liquid can coexist with disorder-induced spin freezing in non-Kramers pyrochlores.
  • The ground-state selection in these materials is sensitive to small amounts of disorder that shift the system across phase boundaries.
  • Two distinct dynamical timescales and anisotropic correlations remain observable even after the system freezes.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Similar disorder effects could be tested by deliberately introducing controlled defects into other non-Kramers pyrochlores to map the same boundary.
  • The framework suggests that sample-to-sample variations in freezing temperatures reported across the Pr pyrochlore family may largely reflect differences in disorder levels rather than differences in the underlying exchange parameters.
  • If the phase diagram is general, then reducing disorder in Pr2Sn2O7 should push the system deeper into the quantum spin-ice regime without changing the high-temperature correlations.

Load-bearing premise

The spin freezing at 0.15 K is caused primarily by disorder rather than by an intrinsic feature of the ideal lattice.

What would settle it

A measurement on a substantially cleaner single crystal of Pr2Sn2O7 that shows the absence of spin freezing or a much lower freezing temperature would falsify the disorder-driven interpretation.

Figures

Figures reproduced from arXiv: 2508.19248 by Adam A. Aczel, Andrey A. Podlesnyak, Benjamin A. Frandsen, Brenden R. Ortiz, Joseph A. M. Paddison, Jue Liu, Matthias D. Frontzek, Miles Knudtson, Si Athena Chen, Stephen D. Wilson, Yi Luo.

Figure 1
Figure 1. Figure 1: FIG. 1. A qualitative phase diagram of the antiferromagnetic Ising [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Pair distribution function (PDF) analysis of Pr [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. Magnetic diffuse scattering of Pr [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. Bulk characterization of flux-grown single-crystal Pr [PITH_FULL_IMAGE:figures/full_fig_p005_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. Neutron spectroscopy of single-crystal Pr [PITH_FULL_IMAGE:figures/full_fig_p006_5.png] view at source ↗
read the original abstract

Magnetic pyrochlores with non-Kramers rare-earth ions provide a platform for exploring emergent gauge physics and quantum spin-ice behavior, yet the influence of structural disorder on their ground states remains insufficiently understood. Here we combine bulk characterization and single-crystal neutron-scattering measurements to investigate the non-Kramers pyrochlore Pr2Sn2O7. At temperatures below ~1 K, the system exhibits key hallmarks of quantum spin-ice physics, including anisotropic spin-ice correlations and two distinct dynamical timescales. Upon further cooling, however, we observe a complete spin-freezing transition at T_f ~ 0.15 K, accompanied by recovery of the full nuclear Schottky anomaly, the emergence of a gapped magnetic excitation, and the development of incipient (100) magnetic correlations. Comparison with related Pr-based pyrochlores places Pr2Sn2O7 near the spin-frozen boundary of a disorder-perturbed phase diagram. These results establish a disorder-driven framework for how quantum spin-ice behavior evolves into frozen ground states, demonstrating that proximity to a quantum spin liquid can coexist with disorder-induced spin freezing in non-Kramers pyrochlores.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 2 minor

Summary. The manuscript reports bulk characterization and single-crystal neutron-scattering measurements on the non-Kramers pyrochlore Pr2Sn2O7. Below ~1 K the system displays anisotropic spin-ice correlations and two dynamical timescales, consistent with quantum spin-ice physics. Further cooling reveals a spin-freezing transition at Tf ~ 0.15 K, accompanied by recovery of the full nuclear Schottky anomaly, a gapped magnetic excitation, and incipient (100) magnetic correlations. The authors interpret these findings as a disorder-induced proximate quantum spin ice phase and place Pr2Sn2O7 near the spin-frozen boundary of a disorder-perturbed phase diagram for Pr-based pyrochlores.

Significance. If the central interpretation is confirmed, the work supplies a concrete experimental example of how structural disorder can drive the evolution from quantum spin-ice correlations to a frozen state while preserving proximity to a quantum spin liquid. The combination of bulk thermodynamics and neutron data on a single non-Kramers pyrochlore adds a useful data point to the growing literature on disorder effects in these materials.

major comments (1)
  1. [Abstract and final paragraph] Abstract and final paragraph: The assertion that the Tf ≈ 0.15 K spin freezing is disorder-induced and that the system lies near the spin-frozen boundary relies on qualitative comparison with other Pr pyrochlores and schematic phase-diagram placement. No quantitative disorder metric—such as refined cation/oxygen occupancies from diffraction or an effective random-field strength extracted from specific-heat modeling—is reported for the measured crystal. Without this link the causal attribution to disorder remains an inference rather than a direct consequence of the data.
minor comments (2)
  1. [Methods/Experimental details] The manuscript should provide a dedicated section or appendix detailing the neutron data reduction, background subtraction, and error propagation procedures that underlie the reported anisotropic correlations, two timescales, and gapped mode.
  2. [Figures and captions] Figure captions and text should explicitly state the temperature ranges, wave-vector ranges, and fitting models used to extract the two dynamical timescales and the gapped excitation energy.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful reading of our manuscript and for the positive assessment of its significance. We address the major comment below and propose revisions to strengthen the presentation of our interpretation.

read point-by-point responses

  1. Referee: [Abstract and final paragraph] Abstract and final paragraph: The assertion that the Tf ≈ 0.15 K spin freezing is disorder-induced and that the system lies near the spin-frozen boundary relies on qualitative comparison with other Pr pyrochlores and schematic phase-diagram placement. No quantitative disorder metric—such as refined cation/oxygen occupancies from diffraction or an effective random-field strength extracted from specific-heat modeling—is reported for the measured crystal. Without this link the causal attribution to disorder remains an inference rather than a direct consequence of the data.

    Authors: We appreciate the referee's point regarding the need for a more direct link between the observed spin freezing and disorder. While our manuscript does not include a refined structural analysis for disorder parameters in the specific crystal studied (as the neutron scattering experiment was optimized for magnetic correlations rather than nuclear structure), the interpretation is grounded in the systematic comparison with other Pr pyrochlores where such metrics have been established in the literature. In the revised version, we will modify the abstract and the final paragraph to explicitly state that the placement near the spin-frozen boundary is inferred from this comparative analysis and the characteristic signatures of disorder effects (such as the low freezing temperature and gapped excitations). Additionally, we will consider adding a brief modeling of the specific-heat data to estimate an effective random-field strength if it can be done without introducing new assumptions. This will make the causal attribution clearer while remaining faithful to the data presented. revision: yes

Circularity Check

0 steps flagged

No circularity: purely experimental observations and external comparisons

full rationale

The manuscript is an experimental report based on bulk characterization and single-crystal neutron scattering. All central observations (anisotropic spin-ice correlations below ~1 K, complete spin freezing at T_f ~ 0.15 K, gapped excitations, incipient (100) order, and recovery of the nuclear Schottky anomaly) are presented as direct data products. The interpretive claim of a 'disorder-induced proximate quantum spin ice phase' is reached by qualitative placement relative to other Pr-based pyrochlores and a schematic disorder-perturbed phase diagram; no equations, fitted parameters renamed as predictions, self-definitional loops, or load-bearing self-citation chains appear in the provided text. The derivation chain is therefore self-contained against external benchmarks and contains no reductions by construction.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Experimental condensed-matter study that relies on established interpretation of neutron scattering and thermodynamic data; no new free parameters, axioms beyond standard physics, or invented entities are introduced.

axioms (1)
  • domain assumption Neutron scattering intensity maps magnetic spin correlations in pyrochlore lattices
    Invoked to interpret anisotropic spin-ice correlations and (100) features.

pith-pipeline@v0.9.0 · 5787 in / 1350 out tokens · 35250 ms · 2026-05-18T20:36:01.118661+00:00 · methodology

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Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Influence of controlled disorder on the dipolar spin ice state of Ho-based pyrochlores

    cond-mat.str-el 2026-01 unverdicted novelty 4.0

    Controlled disorder in Ho2GaSbO7 and Ho2ScSbO7 preserves the dipolar spin-ice state but generates disorder-induced quantum fluctuations via splitting of the non-Kramers ground-state doublet.