{"id":"18074b5b-ea3a-4372-9fbc-af5987a7c0eb","arxiv_id":"2412.05459","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":7.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"In LaRu3Si2, the superconducting critical temperature peaks in the same pressure range where charge order and magnetoresistance are strongest, indicating they are linked.","lead":"By squeezing kagome superconductor LaRu3Si2 to pressures up to 40 GPa, scientists found its critical temperature rises to 9 K and then falls, forming a dome. The same dome appears in charge-order-related signals, suggesting superconductivity and charge order reinforce each other in this material.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The central correlation between loss of long-range charge order and Tc suppression rests on identifying diffuse X-ray scattering as the same (1/4,0,0)/(1/6,0,0) charge order, which the paper does not demonstrate.","rationale":"The paper's strongest claim is that superconductivity and charge order are 'closely tied' in LaRu3Si2, with Tc optimized when charge order and normal-state responses are optimized. The most direct evidence for this is the coincidence between the loss of long-range charge order (transition to diffuse scattering at ~12.5 GPa) and the onset of Tc suppression. The reader identifies the interpretation of the diffuse scattering as the weakest assumption, and I agree. The text states only that diffuse intensity emerges at the same onset temperature as Tco,II, but never demonstrates that it is centered at the same propagation vectors. Without that, the diffuse scattering could be a distinct structural feature, and the correlation would be spurious. I also note a compounding issue: transport and X-ray measurements used different pressure media (NaCl vs He), so the pressure conditions differ. However, the diffuse-scattering identification is logically prior; if it fails, the central correlation fails regardless of pressure medium. I recommend keeping the CONDITIONAL verdict; the proposed test—checking the wavevector of the diffuse peaks in the existing public dataset—could either validate or invalidate the key correlation without new experiments.","tokens_in":11347,"tokens_out":5797,"duration_ms":56983,"concrete_test":"Perform a quantitative analysis of the diffuse scattering at 19.8 GPa (Fig. 5l and p): fit the diffuse intensity distribution in reciprocal space and extract the peak centers. Compare these centers to the known (1/4,0,0) and (1/6,0,0) wavevectors and to the fundamental Bragg positions. If the diffuse peaks are not located at the same reduced wavevectors (or are at incommensurate positions), the interpretation as short-range versions of the original charge orders is invalid and the central correlation fails. This test can be done on the existing dataset since the raw diffraction images are publicly available at the ESRF link.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The most load-bearing assumption is that the broad diffuse X-ray scattering observed above 12 GPa (Fig. 5l-p) represents short-range remnants of the same (1/4,0,0) and (1/6,0,0) charge orders that exist at lower pressures. The text (Section II) states only that diffuse intensity emerges at the same onset temperature Tco,II, but it never reports the wavevector of this diffuse scattering. If the diffuse intensity is not centered at q=(1/4,0,0)/(1/6,0,0) or its symmetry equivalents, it could be a distinct structural distortion, a pressure-induced lattice disorder, or a different modulation, in which case the correlation between the loss of long-range order and the downturn of Tc is not established. This correlation is the primary evidence for the paper's central claim that superconductivity is 'closely tied' to the charge-ordered state. A second, compounding issue is that the transport measurements (which define Tc) used NaCl as a pressure medium, while the X-ray charge-order measurements used helium; non-hydrostatic stress in NaCl above ~10 GPa could independently broaden and suppress superconductivity, creating a spurious coincidence with the diffuse-scattering onset. Thus the claim requires both that the diffuse scattering is the same charge order and that the Tc suppression is intrinsic.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript reports a high-pressure study of the kagome superconductor LaRu3Si2 combining electrical resistivity, magnetoresistance, and single-crystal X-ray diffraction. The authors find that Tc rises from 6.5 K at ambient pressure to about 9 K at 2 GPa, stays nearly constant to about 12 GPa, and then decreases to about 2 K at 38-40 GPa, yielding a dome-shaped phase diagram. The resistivity anomaly at T* (~35 K) and the low-temperature magnetoresistance both show a similar dome-shaped pressure dependence. X-ray diffraction shows that the (1/4,0,0) and (1/6,0,0) charge orders remain sharp up to ~12 GPa, above which only broad diffuse scattering is observed. The authors interpret this as a transition to short-range charge order and argue that superconductivity is not competitive but 'closely tied' to charge order, with Tc optimized when charge order and normal-state electronic responses are strongest.","tokens_in":11666,"tokens_out":8315,"duration_ms":77191,"significance":"If the central claim holds, this is a valuable experimental case of a positive correlation between charge order and superconductivity in a kagome system, contrasting with the more common competition scenario in cuprates, TMDs, and AV3Sb5. The pressure-dependent data set is comprehensive and includes direct X-ray evidence for the charge-order wavevectors, and the proposed strain route to further enhance Tc is a concrete falsifiable prediction. However, the key interpretation that the diffuse scattering above 12 GPa represents short-range order of the same (1/4,0,0)/(1/6,0,0) charge orders is not demonstrated, and the pressure-media mismatch between transport (NaCl) and X-ray (He) measurements complicates the quantitative correlation. The paper is therefore significant if the diffuse-scattering identification can be corroborated.","major_comments":[{"comment":"The identification of the diffuse scattering at high pressure as short-range order of the same (1/4,0,0) and (1/6,0,0) charge orders is not demonstrated. The text states that 'broad, diffuse scattering intensity emerges at the same onset temperature (Tco,II)' but does not report the wavevector of this diffuse intensity. The only low-temperature diffraction data above 12 GPa appear to be at 19.8 GPa (Fig. 5l-p), so the placement of the 'short-range charge order' region in Fig. 1 rests on a single pressure point. To support the central claim that the loss of long-range charge order correlates with the suppression of Tc, the authors should show reciprocal-space maps or line cuts at low temperature above 12 GPa with the diffuse intensity centered at q=(1/4,0,0) and (1/6,0,0) (or symmetry equivalents), and ideally extract a correlation length. Without this, the diffuse scattering could be a distinct structural distortion or pressure-induced disorder, and the claimed correlation would not be established.","section":"Section II, Fig. 5(l-p)"},{"comment":"The transport measurements that determine Tc use NaCl as the pressure-transmitting medium, while the X-ray charge-order measurements use helium (Section V.B). NaCl becomes non-hydrostatic at pressures above roughly 10 GPa, and deviatoric stress can broaden and suppress superconductivity independently of the intrinsic pressure response. The downturn of Tc above approximately 10-12 GPa could therefore be influenced by the pressure medium rather than being a purely electronic effect. Since the paper draws a quantitative correlation between the Tc downturn and the charge-order transition at ~12.5 GPa measured under helium, the mismatch of pressure conditions is a confound. The authors should either present transport data under a more hydrostatic medium (e.g., helium or neon) or provide an estimate of the non-hydrostatic stress in NaCl at these pressures and discuss its possible effect on Tc.","section":"Section V.A, Fig. 1(c)"},{"comment":"The conclusion that Tc is 'closely tied' to charge order relies in part on assigning the T* resistivity anomaly and the magnetoresistance to charge-order-related electronic responses. These assignments are inherited from previous work (refs 7 and 31); the present paper does not independently show that T* tracks the charge-order wavevector under pressure. The observation that T* and MR display a dome-shaped pressure dependence is thus not, by itself, evidence for a connection between superconductivity and charge order, since T* could be a generic electronic crossover with a similar pressure dependence. The authors should compare the pressure evolution of T* with the X-ray-determined Tco,II (or Tco,I) and, if they do not match, moderate the claim accordingly.","section":"Section III, Fig. 1(d,e)"}],"minor_comments":[{"comment":"The use of 'hydrostatic pressures up to 40 GPa' is misleading because NaCl is used as the pressure medium in transport; it should be described as 'quasi-hydrostatic' or simply 'pressures'.","section":"Abstract and Section V.A"},{"comment":"No error bars are shown for Tc, T*, or the anomaly strength. The authors should state the precision of the determinations (e.g., transition width, thermometer accuracy) and add error bars or at least a statement in the text.","section":"Figures 1(c)-(e) and 2"},{"comment":"The abstract states that Tc 'decreases to 2 K at 40 GPa', but the transport data in Fig. 1(c) and Fig. 2(a) extend to 51 GPa and show Tc ~2 K at 38 GPa. Please clarify the maximum pressure and the value at 40 GPa.","section":"Abstract and Fig. 1(c)"},{"comment":"The onset of the Tc suppression is described as 'beyond 10 GPa' in Section II and 'up to 12 GPa' in the Abstract and Introduction. These statements should be reconciled.","section":"Section II and Abstract"},{"comment":"The anomaly strength is defined as the difference in dR/dT between its maximum at T* and its value at 120 K. The choice of the 120 K reference is not justified; the authors should state whether the result is robust to this choice.","section":"Section II, Fig. 1(d)"},{"comment":"The magnetoresistance is measured with the field perpendicular to what crystallographic direction? The orientation relative to the kagome planes should be stated.","section":"Figure 4 and Section II"},{"comment":"Some references are arXiv preprints (refs 7 and 31); if they have been published in the meantime, the published versions should be cited.","section":"References"}],"recommendation":"major_revision","confidential_remarks":"The paper presents a rich data set and a potentially important phase diagram, but the central interpretation is fragile because the diffuse X-ray scattering is not characterized in q-space. I would recommend asking the authors to provide the wavevector analysis of the diffuse intensity and to address the NaCl vs He pressure-medium issue before publication. The manuscript is not suitable for acceptance in its current form, but the concerns are addressable within the scope of a revision."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The genuinely new result here is the pressure axis: a dome-shaped Tc(P) between 2 and 40 GPa, a matching dome in the T* anomaly and magnetoresistance, and a crossover from long-range to diffuse charge-order scattering above 12 GPa. The transport and X-ray data look carefully collected, and the X-ray data are deposited at ESRF, which is real evidence anyone can check. The paper earns credit for that.\n\nWhere I part ways with the authors is the interpretive leap. The phrase 'pronounced interdependence' overstates what the data show. You have a correlation: Tc starts to drop in the same pressure range where the sharp superlattice peaks turn into diffuse scattering. But the diffuse scattering is never identified as the same (1/4,0,0)/(1/6,0,0) charge order. The text just says broad intensity appears at Tco,II; it never reports the wavevector or the line shape. It could be the same order losing correlation length, or it could be a different distortion, or pressure-induced disorder. Without that identification, the central correlation is not established.\n\nThere is also a technical inconsistency the authors never address: transport used NaCl, X-ray used helium. NaCl is not hydrostatic above ~10 GPa. Non-hydrostatic stress can broaden and suppress Tc on its own, which could create a spurious coincidence between the Tc downturn and the diffuse-scattering onset. This is not fatal, but it is a real confound that a referee will catch.\n\nI would not call the paper circular, but it is somewhat self-referential: T* and Tco,II are defined in the authors' earlier papers, and those definitions are assumed when interpreting the new pressure data. That is fine if the assignments are solid, but the paper does not re-examine them under pressure.\n\nMissing error bars on Tc(P) and T*(P) are a minor annoyance; the trends are probably real, but the precision is overstated.\n\nWho is this for? Experimentalists working on kagome superconductors, charge order, or high-pressure physics. They will get a useful phase diagram and a testable hypothesis. Theory people will not find a mechanism.\n\nRecommendation: send it to peer review. The data deserve referee time, and the diffuse-scattering identification is exactly the kind of question a careful referee can push on. With that fixed, or at least honestly caveated, the paper is a solid contribution.","headline":"New high-pressure phase diagram for LaRu3Si2, but the claim that superconductivity is 'closely tied' to charge order leans on an unverified identification of diffuse scattering.","tokens_in":12203,"tokens_out":1126,"would_cite":true,"duration_ms":14123,"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":"In LaRu3Si2, superconductivity and charge order cooperate under pressure, peaking together at 9 K before both weaken.","keywords":["kagome superconductor","charge order","high pressure","dome-shaped phase diagram","magnetoresistance","LaRu3Si2","superconductivity","diffuse scattering"],"falsifier":"Measure the diffuse scattering above 12 GPa with enough momentum resolution to determine whether the broad intensity is centered at the same two wavevectors as the low-pressure superlattice peaks; if the diffuse signal is not charge order of the same two types, or if an alternative nonhydrostatic pressure medium removes the diffuse signal while Tc keeps its dome shape, the claimed correlation between short-range charge order and Tc suppression would be refuted.","tokens_in":11178,"feed_emoji":"🔬","tokens_out":4170,"duration_ms":41759,"temperature":0.7,"pith_summary":"The paper reports that in the kagome superconductor LaRu3Si2, superconductivity and charge order reinforce each other under pressure rather than compete. Tc rises from 6.5 K at ambient pressure to 9 K by 2 GPa, stays near 9 K up to about 12 GPa, then falls to 2 K by 40 GPa, forming a dome-shaped phase diagram. The normal-state resistivity anomaly at T* and the magnetoresistance follow the same dome, and X-ray diffraction shows that long-range charge order gives way to short-range diffuse scattering just where Tc starts to decline. The authors conclude that Tc is maximized when charge order and the associated electronic responses are optimized, in contrast to cuprates, transition-metal dichalcogenides, and other kagome systems where superconductivity typically competes with charge order.","feed_headline":"Pressure dome links LaRu3Si2 superconductivity to charge order","feed_subtitle":"Tc peaks at 9 K when charge order and electronic responses are strongest, then falls as order becomes short-range.","key_machinery":"The load-bearing objects are the two charge-density-wave propagation vectors in the kagome planes, q=(1/4,0,0) and q=(1/6,0,0), together with the normal-state transport anomalies at Tco,II about 80 K and T* about 35 K. Pressure is the tuning knob: X-ray diffraction maps the crossover from sharp superlattice peaks (long-range order) to broad diffuse scattering above about 12 GPa, while resistivity and magnetoresistance track the strength of the electronic responses that follow the same dome as Tc. The convergence of Tco,I and Tco,II at 12.5 GPa marks the endpoint of long-range order and the start of the short-range diffuse regime where Tc begins to fall.","core_discovery":"The central claim is that LaRu3Si2 displays a pronounced interdependence between superconductivity and charge order: the superconducting critical temperature peaks in the same pressure window in which the charge-order transitions, the T* resistivity anomaly, and magnetoresistance are all strongest, and the onset of Tc suppression coincides with the crossover from long-range to short-range charge order near 12.5 GPa. This is cast as coexistence plus synergy rather than competition, and the authors point to pressure-tuned Ru–Ru bond disproportionation as the microscopic coupling: out-of-plane Ru–Ru distortions associated with the charge-ordered kagome band structure favor a higher Tc.","pith_inferences":["Extension: the paper does not identify the pairing mechanism, but its picture suggests that if the diffuse scattering above 12 GPa represents short-range charge-order fluctuations, then Tc may track the fluctuation spectrum rather than static order; a correlation-length measurement across the dome would test this.","Extension: the authors argue that out-of-plane Ru–Ru distortions matter, so in-plane uniaxial strain should shift Tc more strongly than hydrostatic pressure; this is a direct, testable prediction that goes beyond the reported experiments.","Extension: if the positive coupling between charge order and superconductivity is generic, other kagome superconductors with high-temperature charge order might be optimized by pressure or strain rather than suppressed, which would expand the search space for enhanced Tc."],"forward_implications":["If the claim holds, Tc in LaRu3Si2 is directly tied to the lattice distortions that stabilize charge order, so tuning those distortions should tune superconductivity.","The system becomes a model case where charge order and superconductivity cooperate, providing a counterpoint to the AV3Sb5 kagome family where they compete.","The dome-shaped Tc under pressure, together with its coincidence with optimal electronic responses, suggests the pairing may be unconventional and driven by the same electronic correlations that produce charge order.","The specific pressure landmark at about 12.5 GPa, where long-range order vanishes and Tc starts to decrease, gives a concrete target for future spectroscopic and thermodynamic probes."],"supporting_citations":[{"why":"Establishes LaRu3Si2 as a kagome superconductor with Tc about 6.5 K and nodeless pairing, providing the baseline superconducting state studied here.","marker":"[4]"},{"why":"Reports the primary charge order with (1/4,0,0) propagation and its exceptionally high onset temperature Tco,I about 400 K, the key high-temperature order tracked under pressure.","marker":"[7]"},{"why":"Documents the secondary (1/6,0,0) charge order, the T* anomaly, and the associated magnetic responses, which this paper extends to high pressure.","marker":"[31]"},{"why":"Provides the comparative framework of unconventional charge order and superconductivity in kagome-lattice systems that this paper contrasts with the cooperative behavior in LaRu3Si2.","marker":"[2]"},{"why":"Supplies the theoretical perspective on charge order and superconductivity in kagome materials, framing the expectation of competition that LaRu3Si2 is claimed to defy.","marker":"[15]"},{"why":"Introduces the AV3Sb5 kagome superconductors where charge order and superconductivity are typically competitive, serving as the main contrasting family.","marker":"[10]"},{"why":"Describes the ID27 beamline and high-pressure X-ray diffraction setup used to obtain the reciprocal-space maps and diffuse-scattering data central to the charge-order characterization.","marker":"[39]"}],"fun_headline_variants":["Superconductivity dome tracks charge order in LaRu3Si2","Charge order and superconductivity rise and fall together in kagome metal","Same pressure dome controls superconductivity and charge order in LaRu3Si2","In kagome superconductor, charge order and Tc peak together under pressure","LaRu3Si2 shows superconductivity and charge order move in sync"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"Above 12 GPa, the broad diffuse X-ray scattering that appears at the same onset temperature as Tco,II is assumed to be short-range charge order of the same (1/4,0,0) and (1/6,0,0) types, rather than a separate lattice distortion or pressure-induced disorder.","fun_headline_variants_meta":{"raw":{"variants":["Superconductivity dome tracks charge order in LaRu3Si2","Charge order and superconductivity rise and fall together in kagome metal","Same pressure dome controls superconductivity and charge order in LaRu3Si2","In kagome superconductor, charge order and Tc peak together under pressure","LaRu3Si2 shows superconductivity and charge order move in sync"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.001084,"raw_usage":{"total_tokens":4594,"prompt_tokens":1066,"completion_tokens":3528,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":682,"completion_tokens_details":{"reasoning_tokens":3430}},"tokens_in":682,"tokens_out":3528,"duration_ms":21877,"temperature":1.0,"reasoning_tokens":3430,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T20:42:23.427417+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the diffuse scattering above 12 GPa with enough momentum resolution to determine whether the broad intensity is centered at the same two wavevectors as the low-pressure superlattice peaks; if the diffuse signal is not charge order of the same two types, or if an alternative nonhydrostatic pressure medium removes the diffuse signal while Tc keeps its dome shape, the claimed correlation between short-range charge order and Tc suppression would be refuted.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Establishes LaRu3Si2 as a kagome superconductor with Tc about 6.5 K and nodeless pairing, providing the baseline superconducting state studied here."},{"cited_title":"Charge order above room-temperature in a prototypical kagome superconductor La(Ru$_{1-x}$Fe$_{x}$)$_{3}$Si$_{2}$","cited_arxiv_id":"2309.09255","evidence_quote":"Reports the primary charge order with (1/4,0,0) propagation and its exceptionally high onset temperature Tco,I about 400 K, the key high-temperature order tracked under pressure."},{"cited_title":"and Luetkens, H","cited_arxiv_id":null,"evidence_quote":"Provides the comparative framework of unconventional charge order and superconductivity in kagome-lattice systems that this paper contrasts with the cooperative behavior in LaRu3Si2."},{"cited_title":"Charge order and superconductivity in kagome materials","cited_arxiv_id":null,"evidence_quote":"Supplies the theoretical perspective on charge order and superconductivity in kagome materials, framing the expectation of competition that LaRu3Si2 is claimed to defy."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Introduces the AV3Sb5 kagome superconductors where charge order and superconductivity are typically competitive, serving as the main contrasting family."},{"cited_title":"et al., The high flux nano-X-ray diffraction, fluorescence and imaging beamline ID27 for science under extreme conditions on the ESRF Extremely Brilliant Source","cited_arxiv_id":null,"evidence_quote":"Describes the ID27 beamline and high-pressure X-ray diffraction setup used to obtain the reciprocal-space maps and diffuse-scattering data central to the charge-order characterization."}],"review_version":1}