{"id":"af78d92a-dbcc-4002-939d-5f5338f8cf5a","arxiv_id":"2411.18950","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":4,"one_line_summary":"Field cooling TbMn6Sn6 creates a remanent near-saturation magnetic state that persists up to about 200 K and produces a zero-field anomalous Hall signal that collapses sharply at that temperature.","lead":"Cooling the kagome magnet TbMn6Sn6 in a moderate magnetic field pins its magnetization close to saturation, and the material keeps this state until heated above roughly 200 K, where it switches off suddenly. Because the magnetized state survives in zero applied field, it also produces a zero-field Hall voltage, which the authors connect to strong magnetic anisotropy and exchange interactions.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The 'arrested state' interpretation is not supported over conventional hysteresis remanence: the ~200 K collapse coincides with the vanishing coercivity, yet no glass diagnostics (aging, memory, ac-susceptibility) are provided.","rationale":"The paper reports reproducible TRM and zero-field Hall data with good internal consistency (TRH tracks the anomalous Hall coefficient from hysteresis loops), and the two-batch reproducibility is a real strength. The load-bearing weakness is the attribution of the state to an exotic cluster-glass arrest: all reported features—TRM ≈ Msat, the collapse near 200 K, the sign-mirroring for opposite cooling fields, and the absence of TRM along the ab-plane—are also generic consequences of the large uniaxial anisotropy and coercivity of a conventional hard ferrimagnet. The collapse temperature coincides with where the paper's own M–H loops show the coercivity vanishing, and no standard spin-glass diagnostics (aging, memory, frequency-dependent ac susceptibility) are presented. Thus the central claim is plausible but not yet established. The reader's conditional verdict is appropriate; the proposed coercivity-crossing measurement would settle the interpretation.","tokens_in":9752,"tokens_out":7895,"duration_ms":76413,"concrete_test":"Measure TRM collapse temperature Tc as a function of heating field H_heat = 0, 20, 50, 100, 200 Oe after identical field cooling in 5 kOe, and simultaneously extract the coercive field Hc(T) from low-field M-H loops. If Tc follows Hc(Tc) ≈ H_heat (or, for H_heat = 0, Hc(Tc) ≈ the demagnetizing field), then conventional hysteresis remanence is established; field independence of Tc while Hc(Tc) is not small would support a genuinely arrested state.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim is that field cooling produces an exotic, cluster-glass-like 'arrested state' in TbMn6Sn6, evidenced by TRM equal to Msat and a sharp collapse near 200 K. The alternative, conventional explanation is that the sample is simply left in the positive remanence branch of its hysteresis loop after cooling in 5 kOe. The paper's own Fig. 1(b) shows a square loop at 50 K with coercivity 4.3 kOe that 'almost vanishes above about 200 K'; a 100 Oe or 20 Oe heating field is far too small to move the magnetization off the remanence branch at low T, so M stays near saturation until Hc(T) falls to the order of the applied (or demagnetizing) field, at which point the remanent state collapses. Fig. 3(d) shows that the zero-field TRH matches the H=0 intercept of the isothermal Hall loops, i.e., TRH is just the remanent AHE expected for any ferromagnet with remanent magnetization. Nothing in the data distinguishes this from ordinary domain-wall pinning: no aging, no memory effect, no frequency-dependent ac susceptibility, and no nonlinear susceptibility are reported. The paper itself notes the collapse temperature coincides with where coercivity vanishes and where muon-spin-rotation experiments had indicated enhanced fluctuations, which is exactly the regime expected for loss of hysteresis, not a new arrested state.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper reports thermo-remanent magnetization (TRM) and zero-field Hall resistivity (TRH) measurements on single-crystal TbMn6Sn6 after field cooling in ±5 kOe. On heating in 20–100 Oe or zero field, the magnetization and Hall resistivity retain near-saturation values up to about 200 K and then collapse abruptly within roughly 0.5 K. The authors interpret this as evidence for an arrested, cluster-glass-like magnetic state induced by field cooling, and they describe the zero-field Hall signal as a spontaneous anomalous Hall effect. They also fit the TRH and TRM data to scaling relations (Eqs. 2 and 3) to argue that the two quantities vary conjointly and that the intrinsic contribution dominates.","tokens_in":10042,"tokens_out":3430,"duration_ms":33081,"significance":"The measurements are careful and reproducible across two independently grown batches (B1 and B2), and the observation that the zero-field Hall resistivity follows the remanent magnetization in the same temperature window is a useful confirmation of anomalous Hall scaling in a ferrimagnet. If the arrested-state interpretation were established, the sharp collapse near 200 K would be an interesting phenomenon. However, the central interpretation is not yet supported: the data are quantitatively consistent with ordinary ferromagnetic remanence controlled by the temperature-dependent coercivity, and no discriminating glass diagnostics (aging, memory, ac susceptibility, nonlinear susceptibility) are presented. The paper would be significantly strengthened either by adding such measurements or by reframing the claims as a study of remanence and its Hall signature.","major_comments":[{"comment":"The claim that field cooling produces an 'arrested state' is not distinguished from conventional remanence. The paper's own hysteresis data in Fig. 1(b) show a rectangular loop at 50 K with coercivity 4.3 kOe, with the loop almost vanishing above about 200 K. Cooling in 5 kOe and then applying 20–100 Oe leaves the sample on the positive remanence branch of the hysteresis loop; the magnetization will remain near saturation until Hc(T) falls to the order of the applied (or demagnetizing) field, at which point the remanence collapses. The observed jump near 200 K is therefore exactly where coercivity vanishes, as the authors themselves note. No aging, memory, or ac-susceptibility measurements are presented that would distinguish cluster-glass arrest from ordinary domain-wall pinning. This is a load-bearing interpretive step and must either be supported by such experiments or substantially moderated.","section":"Sec. 3 (TRM results, Fig. 2)"},{"comment":"The zero-field Hall resistivity that matches the H=0 intercept of isothermal Hall loops is the remanent anomalous Hall effect expected from Eq. (1), ρxy = R0H + 4πRsM, with H=0 and M equal to the remanent magnetization. The agreement in Fig. 3(d) confirms the AHE scaling but does not by itself require any exotic arrested state. Calling this a 'spontaneous anomalous Hall effect' is misleading unless the authors demonstrate that the remanence itself cannot be produced by ordinary hysteresis in the same temperature range. Please either provide such a demonstration or use more neutral terminology such as 'remanent anomalous Hall effect.'","section":"Sec. 4 and Fig. 3(d)"},{"comment":"The conclusion that TRH and TRM 'vary conjointly' rests on a two-parameter fit of ρtr_xy/Mtr against ρxx using Eq. (3). Because Mtr appears in the denominator of the plotted quantity, the fit is a weak test: any smooth temperature dependence of Mtr can be absorbed by the two free parameters SH and α′. The manuscript does not report fit residuals, parameter uncertainties, or an independent check where the measured ρtr_xy is compared with the prediction computed from separately measured Mtr and ρxx. Please provide these; otherwise the 'conjointly' claim is not established beyond the visual overlap in Figs. 2 and 3.","section":"Eq. (3) fit and Fig. 4"}],"minor_comments":[{"comment":"The sentence 'The ultrasharp jump in magnetization is also get reflected in our Hall data' contains a grammatical error; it should read 'is also reflected.'","section":"Abstract and main text"},{"comment":"The antisymmetrization procedure used to obtain the green and orange curves is not fully described. Please specify how the data from positive and negative cooling fields were combined and whether the symmetrized curve includes both cooling and heating branches.","section":"Fig. 3(c) caption"},{"comment":"The statement that 'Mtr is as high as Msat' would benefit from a quantitative comparison with error bars, since the red triangles and the heating curve appear to overlap but no numerical difference or uncertainty is given.","section":"Sec. 3, Fig. 2(b) discussion"},{"comment":"The quality of the fit to Eq. (2) is not quantified. Please report the goodness-of-fit (e.g., R² or chi-square) and the temperature range used, and enlarge the inset so that the data and fit line are legible.","section":"Eq. (2) and Fig. 4 inset"}],"recommendation":"major_revision","confidential_remarks":"The underlying measurements appear sound and the paper could be suitable for a rapid-communication format if the interpretation is made more modest. As written, the central 'arrested state' claim is likely to draw criticism because the data are explained by conventional coercivity-controlled remanence. I would suggest the authors consider performing a simple control: after zero-field cooling, apply a 5 kOe field at low temperature, remove it, and measure the thermal decay of the resulting isothermal remanence. If that curve reproduces the TRM and TRH behavior, the 'arrested' description loses its specificity. Also, the claim of a 'spontaneous' Hall effect should be toned down unless the authors can distinguish their zero-field signal from the standard remanent AHE."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Two things to know. The measurements are likely real and reproducible: two batches, TRM sits at Msat up to ~200 K, and the zero-field Hall resistivity matches the anomalous Hall from loops. That is a fine, if not earth-shattering, result. The second thing is that the 'arrested state' interpretation is not supported by the paper's own data. The collapse near 200 K coincides with where the hysteresis loop coercivity vanishes (Fig. 1b). After cooling in 5 kOe onto the saturated branch of a square loop, heating in 20–100 Oe simply tracks that branch until Hc(T) falls below the applied/demagnetizing field. That is conventional remanence, not a glassy arrested phase. There is no aging, memory, or ac-susceptibility data to justify the cluster-glass language, and the muon-fluctuation citation is too circumstantial.\n\nWhat earns credit: the observation is new for TbMn6Sn6, the two-batch consistency is good, and the AHE remanence connection is clearly demonstrated. The fit to Eqns. (2) and (3) is standard and gives sane parameters; it doesn't prove 'conjoint variation' but that's a minor overstatement.\n\nThe 'spontaneous anomalous Hall' is just the remanent AHE of any ferromagnet with Msat-like remanence; it is nicely captured here but not a new mechanism. So the title and abstract oversell. The material is known to have high anisotropy and a spin-reorientation transition; the simple explanation should have been the default.\n\nI would send this to review, because the raw data deserve a public record and the interpretation is fixable. A referee should insist on either glass diagnostics (ac susceptibility, aging) or a revised narrative that says 'large remanence and zero-field AHE' without the exotic-arrested-state claim. If the authors won't budge on that, the paper is not acceptable. But as a measurement paper with a corrected interpretation, it would be a reasonable short report.","headline":"Believable measurements of large remanent magnetization and zero-field Hall in TbMn6Sn6, but the 'arrested state' framing is just ordinary hysteresis remanence until the interpretation is fixed.","tokens_in":10641,"tokens_out":4283,"would_cite":false,"duration_ms":41360,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"Field cooling locks TbMn6Sn6's full magnetization until a half-kelvin collapse near 200 K.","keywords":["thermo-remanent magnetization","spontaneous anomalous Hall effect","kagome ferrimagnet","TbMn6Sn6","field-cooled arrested state","zero-field Hall resistivity","spin reorientation","uniaxial anisotropy"],"falsifier":"After field cooling in 5 kOe, stop the zero-field heating at 150 K and monitor magnetization for several hours; if $M_{\\text{tr}}$ relaxes toward the value expected from the hysteresis loop, or if pausing the heating at 150 K erases or weakens the subsequent 200 K jump, the arrested-state interpretation fails. A complementary check is to measure ac susceptibility or a field-stop memory protocol: a true glassy arrest produces aging and memory, whereas ordinary coercivity-driven remanence does not.","tokens_in":9523,"feed_emoji":"🧲","tokens_out":10504,"duration_ms":88161,"temperature":0.7,"pith_summary":"The paper reports that cooling the kagome ferrimagnet TbMn6Sn6 in a moderate magnetic field (5 kOe) leaves it with a magnetization equal to its saturation value, and that this state survives on rewarming in fields as small as 20 Oe or even zero. The retained magnetization collapses within 0.5 K near 200 K, and exactly at that temperature an equally sharp step appears in the Hall resistivity measured in zero field. The paper interprets the two observations as one phenomenon: a field-induced arrested magnetic state whose large remanent moment drives a spontaneous anomalous Hall effect, both of which release together at a well-defined temperature. If correct, the compound gives a single material where a full magnetic polarization and its associated Berry-curvature Hall signal can be written by field cooling and read back with no applied field.","feed_headline":"Magnet holds full magnetization to 200 K, then loses it in 0.5 K","feed_subtitle":"Field cooling the kagome magnet TbMn6Sn6 freezes a saturation-sized state that emits a zero-field Hall signal.","key_machinery":"The central object is the field-cooled arrested state: cooling in 5 kOe along the easy $c$ axis aligns the strongly anisotropic spins and freezes them into a configuration that stays at saturation when the field is removed. The named measurement objects are thermo-remanent magnetization ($M_{\\text{tr}}$), the magnetization retained while heating in a small or zero field after field cooling, and thermo-remanent Hall resistivity ($\\rho_{xy}^{\\text{tr}}$), the zero-field Hall response of that same state. The argument that $\\rho_{xy}^{\\text{tr}}$ is a genuine spontaneous anomalous Hall effect is carried by the scaling relation $\\rho_{xy} = S_H M \\rho_{xx}^2(1+\\alpha'/\\rho_{xx})$, from Eq. (3) of the paper, which is fitted to the joint temperature dependence of $\\rho_{xy}^{\\text{tr}}/M_{\\text{tr}}$ and $\\rho_{xx}$ and traces the data well below 200 K; this ties the Hall signal directly to the retained magnetization rather than to an applied field. The sharp release near 200 K is attributed to cooperative de-arrest, supported by the strong intersite exchange ($J \\sim -29$ meV) and by the onset of magnetic fluctuations in that temperature range.","core_discovery":"Stated in the authors' terms: TbMn6Sn6, a collinear ferrimagnet with a kagome Mn lattice and a spin-reorientation transition near 310 K, is a topological magnet whose anomalous Hall conductivity comes from Berry curvature. When the crystal is cooled under $H_{\\text{cool}} = 5$ kOe applied along the $c$ axis and then heated in 20–100 Oe or in zero field, the magnetization $M_{\\text{tr}}$ stays pinned at the saturation value $M_{\\text{sat}}$ up to about 200 K, then falls by more than an order of magnitude in a jump that occurs within 0.5 K. The zero-field Hall resistivity during the same protocol, called the thermo-remanent Hall effect $\\rho_{xy}^{\\text{tr}}$, matches the anomalous Hall resistivity extracted from hysteresis loops, both in magnitude and in its sharp collapse near 200 K; cooling in the opposite field produces the mirror-image response. The authors conclude that field cooling arrests the spin system in an energy minimum, that the arrest is broken only when the uniaxial anisotropy weakens or thermal fluctuations grow, and that the remanent magnetization itself is enough to produce a spontaneous anomalous Hall effect.","pith_inferences":["Because the 200 K collapse coincides with the temperature where the hysteresis loop and coercivity nearly vanish, the 'arrested' state may be the high-coercivity branch of ordinary magnetization reversal; an aging or time-decay experiment would decide without invoking new physics.","The sign of the cooling field sets the sign of both the remanent magnetization and the zero-field Hall voltage, so field cooling could serve as a write step and zero-field Hall measurement as a read step; repeated cycling would test whether the write-read sequence is durable.","If the zero-field Hall signal faithfully reproduces the anomalous Hall effect, the field-cooling protocol gives a way to measure Berry-curvature Hall response without applying a field, which could simplify transport studies of kagome magnets at high temperatures."],"forward_implications":["A field-cooled sample heated in 20 Oe or 100 Oe follows the 5 kOe cooling curve to about 200 K, so the remanent state carries the full saturation moment rather than a reduced fraction.","The zero-field Hall resistivity after field cooling matches the anomalous Hall resistivity from hysteresis loops, so the intrinsic Berry-curvature Hall signal can be read with no applied field.","The magnetization and the Hall signal both collapse within 0.5 K near 200 K, so the same event switches off the magnetic polarization and the spontaneous Hall voltage.","The effect is absent for fields perpendicular to the c axis and present for fields along the c axis, identifying the uniaxial anisotropy as the ingredient that makes the arrested state possible.","Fits of the thermo-remanent Hall to the anomalous Hall scaling relation indicate the intrinsic contribution dominates in the zero-field state as well."],"supporting_citations":[{"why":"Supplies the standard thermo-remanent magnetization behavior of spin glasses that the paper invokes as the glassy-arrest template for TbMn6Sn6.","marker":"[22]"},{"why":"Provides the magnetic-glass/arrested-transition framework used to describe the field-cooled state as an arrest in an energy landscape.","marker":"[23]"},{"why":"A second arrested-state reference used alongside [23] for field-induced arrest and its sharp release.","marker":"[24]"},{"why":"Earlier study predicting cluster-glass-like features in TbMn6Sn6 and reporting anomalous thermal transport, cited to assign the TRM to a glassy magnetic state.","marker":"[14]"},{"why":"Gives Eq. (3), the relation between Hall resistivity, magnetization, and longitudinal resistivity used to show TRH and TRM vary conjointly.","marker":"[21]"},{"why":"Muon-spin-rotation observation of magnetic fluctuations in the same temperature range, supporting the 200 K de-arrest threshold.","marker":"[26]"},{"why":"Reports the strong intersite exchange J ~ -29 meV that the paper uses to explain cooperative spin behavior behind the sharp jump.","marker":"[27]"},{"why":"Establishes TbMn6Sn6 as a topological magnet with Chern-gapped Dirac fermions and provides the saturation moment and high-field magnetization baselines used throughout.","marker":"[9]"}],"fun_headline_variants":["Kagome magnet shrugs off heat until 200 K, then plunges","Zero-field Hall signal appears in field-frozen TbMn6Sn6","Arrested spin state yields spontaneous Hall effect in TbMn6Sn6","TbMn6Sn6: trapped magnetization breaks in 0.5 K at 200 K","Ultrasharp 0.5 K magnetization collapse in kagome magnet at 200 K"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The interpretation rests on the premise that the saturated magnetization retained after field cooling is a genuinely arrested magnetic state, rather than ordinary remanence from a wide hysteresis loop, because the paper relies on the sharp collapse to label the state exotic and does not include relaxation, aging, or memory measurements to separate the two.","fun_headline_variants_meta":{"raw":{"variants":["Kagome magnet shrugs off heat until 200 K, then plunges","Zero-field Hall signal appears in field-frozen TbMn6Sn6","Arrested spin state yields spontaneous Hall effect in TbMn6Sn6","TbMn6Sn6: trapped magnetization breaks in 0.5 K at 200 K","Ultrasharp 0.5 K magnetization collapse in kagome magnet at 200 K"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.001682,"raw_usage":{"total_tokens":6667,"prompt_tokens":941,"completion_tokens":5726,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":557,"completion_tokens_details":{"reasoning_tokens":5614}},"tokens_in":557,"tokens_out":5726,"duration_ms":39352,"temperature":1.0,"reasoning_tokens":5614,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-12T10:42:16.915232+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"After field cooling in 5 kOe, stop the zero-field heating at 150 K and monitor magnetization for several hours; if $M_{\\text{tr}}$ relaxes toward the value expected from the hysteresis loop, or if pausing the heating at 150 K erases or weakens the subsequent 200 K jump, the arrested-state interpretation fails. A complementary check is to measure ac susceptibility or a field-stop memory protocol: a true glassy arrest produces aging and memory, whereas ordinary coercivity-driven remanence does not.","supporting_citations":[{"cited_title":"Mathieu , author P","cited_arxiv_id":null,"evidence_quote":"Supplies the standard thermo-remanent magnetization behavior of spin glasses that the paper invokes as the glassy-arrest template for TbMn6Sn6."},{"cited_title":"Chaddah , author K","cited_arxiv_id":null,"evidence_quote":"Provides the magnetic-glass/arrested-transition framework used to describe the field-cooled state as an arrest in an energy landscape."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"A second arrested-state reference used alongside [23] for field-induced arrest and its sharp release."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Gives Eq. (3), the relation between Hall resistivity, magnetization, and longitudinal resistivity used to show TRH and TRM vary conjointly."},{"cited_title":"Mielke III , author W","cited_arxiv_id":null,"evidence_quote":"Muon-spin-rotation observation of magnetic fluctuations in the same temperature range, supporting the 200 K de-arrest threshold."},{"cited_title":"Huang , author W","cited_arxiv_id":null,"evidence_quote":"Reports the strong intersite exchange J ~ -29 meV that the paper uses to explain cooperative spin behavior behind the sharp jump."}],"review_version":1}