{"id":"fad3c104-9312-41ce-802f-8686b83bd907","arxiv_id":"2607.26990","paper_version":1,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":6.0,"correctness_risk":"low","formal_verification":"none","parameter_count":3,"one_line_summary":"In clean La3Ni2O7 single crystals, pressure suppresses two density-wave orders and yields zero-resistance superconductivity from a Planckian T-linear strange metal.","lead":"High-quality La3Ni2O7 crystals show two density-wave orders with opposite pressure trends; superconductivity appears only after both are suppressed, from a T-linear strange-metal state at the Planckian limit. The work supplies absolute resistivities and anisotropy that prior powder and small-crystal studies lacked.","discovery_kind":"extension","skeptic_critique":{"model":"grok-4.5","headline":"Planckian α rests on ambient ARPES FS parameters plus a theoretical 20% vF boost at 20 GPa; that rescaling is the softest link in the strongest claim.","rationale":"The reader already isolated the same soft spot: α is model-dependent and imports ambient ARPES plus a theoretical bandwidth boost. Multi-sample transport, the contrasting P-evolution of T1/T2, the anisotropy jump, and zero-resistance SC near DW suppression are documented at normal standards for high-P nickelate work and do not require a verdict change. The Planckian quantitative claim remains conditional on better high-P electronic-structure input, which is exactly why CONDITIONAL is appropriate and why no further downgrade (or upgrade) is warranted. Unpublished structural boundary data are a secondary caveat already noted by the reader and do not displace the α issue as the single most load-bearing concern for the stated strongest claim.","tokens_in":24991,"tokens_out":690,"duration_ms":32783,"concrete_test":"Recompute α at 20 GPa replacing the ambient ARPES (kF, vF) × 1.2 ansatz with Fermi-surface parameters from a DFT+U or DFT+DMFT calculation performed on the experimental tetragonal structure at 20 GPa (or, if available, high-P quantum-oscillation frequencies). If the new α falls outside ~0.5–3, the “Planckian dissipation” clause of the strongest claim is not supported by the present data.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim pairs two results: (i) zero-resistance SC appears where T1 and T2 are suppressed, and (ii) the normal state is Planckian (α = 1.6 ± 0.4). Claim (i) is carried by multi-crystal ρ(T,P) and is comparatively direct. Claim (ii) is not. Supplementary estimation of α inserts ambient-pressure ARPES kF and vF for the α/β sheets (Yang et al.), multiplies vF by a ~20% bandwidth enhancement taken from ambient-to-20 GPa DFT (Zhang et al.; Jiang et al.), and feeds the result into the multi-band Drude form with bilayer spacing d = 10.26 Å. High-P ARPES or quantum oscillation data do not exist in the manuscript, and the structural/electronic reconstruction across the ortho–tetra boundary (itself cited as unpublished Sasaki et al.) can change sheet areas and masses by more than the quoted 20%. Because α scales with Σ kFi vFi, a factor-of-two error in the high-P FS parameters moves α well outside the “order-1” Planckian window even though T-linear ρ and dρ/dT are measured cleanly. The Planckian half of the strongest claim therefore hangs on an uncontrolled extrapolation.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.5","summary":"The manuscript reports high-pressure in-plane and out-of-plane resistivity on multiple high-quality La3Ni2O7 single crystals, establishing a P–T phase diagram that resolves two density-wave anomalies (T1, T2) with contrasting pressure dependences, a strong enhancement of low-T resistivity and anisotropy across the orthorhombic–tetragonal boundary near 8–10 GPa, and zero-resistance superconductivity that appears only after both DW features are suppressed. Above Tc at 18–20 GPa the ab-plane resistivity is T-linear from ~80–300 K with near-zero residual resistivity; using ambient-pressure ARPES Fermi-surface parameters (rescaled by a DFT-motivated ~20% bandwidth enhancement) the authors extract a Planckian coefficient α = 1.6 ± 0.4. Crystal quality is supported by synchrotron XRD (Am2m, no detectable O vacancies), STEM/EDS (no RP intergrowths), and multi-crystal reproducibility of the overall phase diagram.","tokens_in":25290,"tokens_out":1752,"duration_ms":48101,"significance":"Absolute resistivities, ρc/ρab anisotropy via the Montgomery method, and a multi-crystal transport phase diagram fill a genuine gap left by prior polycrystalline and small-crystal work on bilayer nickelates. The demonstration that zero-resistance SC onsets at the full suppression of both DW anomalies, together with a clean T-linear normal state, is a substantial and falsifiable experimental contribution. The crystal-quality documentation (Am2m charge order, stoichiometry, stacking-fault-free bilayers) and cross-sample comparison (including polycrystalline data) are particular strengths. If the phase-diagram and anisotropy results hold, they become reference data for theories of intertwined DW order and pairing in La3Ni2O7; the Planckian placement is secondary and more assumption-dependent.","major_comments":[{"comment":"Supplementary estimation of α (and Fig. 4c): α = 1.6 ± 0.4 is obtained from the measured dρab/dT by inserting ambient-pressure ARPES kF and vF for the α/β sheets (Yang et al.), multiplying vF by a ~20% enhancement taken from ambient-to-20 GPa DFT, and using bilayer spacing d = 10.26 Å in the multi-band Drude form of Bruin et al. No high-P Fermi-surface or mass data are provided. Because α ∝ Σi kFi vFi, a factor-of-two change in high-P sheet parameters (plausible across the ortho–tetra reconstruction) moves α well outside the order-1 window even though T-linear ρ is measured cleanly. The abstract and conclusion state that the scattering rate “falls within a regime of the Planckian limit” as a defining feature. Please (i) report a sensitivity band on α under reasonable variations of kF, vF, and n; (ii) separate the model-independent observation (T-linear ρ, small residual) from the model-d","section":"Supplementary: Estimation of the scattering rate; Fig. 4c,f; Abstract; Conclusion"},{"comment":"Figs. 4b,d,e and main text (“slight sample-dependent response”): crystal 2#-e at 18–20 GPa closely matches crystal 2#-a at 12–14 GPa in magnitude, T-dependence, and SC onset—an offset of several GPa. The paper still advertises a “high-precision” P–T diagram. The overall topology is reproducible, but the absolute pressure scale for DW suppression and SC onset is sample-dependent at a level comparable to the claimed precision. Quantify the pressure uncertainty (calibration, medium, local strain) and state explicitly which features are robust in absolute P and which only in relative ordering (T1 vs T2 vs Tc).","section":"Reproducibility and sample-dependent pressure response; Fig. 4b,d,e"},{"comment":"The orthorhombic–tetragonal boundary near 8–10 GPa is central to the interpretation of the jump in T1, the rise in low-T ρ and ρc/ρab, and the exclusive appearance of SC in the tetragonal phase, yet it is cited only as unpublished Sasaki et al. [34]. For a load-bearing structural assignment, either include the essential diffraction evidence (even as a brief Extended Data panel) or clearly mark the boundary as adopted from external work and discuss how much of the transport interpretation survives if the structural line shifts by a few GPa.","section":"Introduction; Fig. 2e; Fig. 3; Ref. [34]"},{"comment":"Assignment of T1 and T2 (Extended Data Figs. 1, 3, 7): T2 is identified with SDW following prior work; T1 is a “DW-like” anomaly whose microscopic character is left open, yet both are treated symmetrically as “density-wave phases” whose full suppression coincides with zero-resistance SC. Several additional features (resistivity max/min, high-T upturn, “tiny anomalies” below T1) are plotted on the phase diagram without a clear hierarchy. Tighten the operational definitions (derivative criteria, reproducibility across ρab vs ρc) and avoid over-interpreting T1 as a long-range DW order parameter until microscopic probes under pressure are available.","section":"Transport signature of density-wave phases; Extended Data Fig. 1; Fig. 2e"}],"minor_comments":[{"comment":"Fig. 1 panel labels in the caption (b,c,e,d,f,g) do not match the order described in the text; renumber for consistency.","section":"Fig. 1 caption"},{"comment":"In the Planckian paragraph, “0.28 μΩ cm/K” is quoted in the text while Fig. 4f reports 0.264 and 0.287 μΩ cm K−1 at 18 and 20 GPa; state which slope enters α.","section":"Planckian dissipation; Fig. 4f"},{"comment":"Montgomery geometry and the correction for pressure-induced lattice contraction are mentioned only briefly; a short Extended Data note on contact placement, aspect-ratio uncertainty, and the size of the contraction correction would help others reproduce ρc/ρab.","section":"Methods; Fig. 3 inset"},{"comment":"Several references are preprints or “unpublished” (e.g. [27], [34], [37]); update status where possible and ensure that claims resting on them are flagged as such in the main text.","section":"References"},{"comment":"Typographical inconsistencies: “deceases” → “decreases” (p. 5); mixed “behavio(u)r”; “Orth o” spacing in figure labels; “T S” → “Ts”.","section":"Main text; figure labels"},{"comment":"Abstract claims “large single crystals” enabling absolute resistivity; give typical lateral dimensions in the abstract or opening results paragraph so the advance over prior work is quantitative.","section":"Abstract; Oxygen-stoichiometric… section"}],"recommendation":"minor_revision","confidential_remarks":"Strong experimental paper; the multi-crystal phase diagram, absolute ρ, and anisotropy are journal-appropriate even if the Planckian half is caveated. The main risk is over-selling α = 1.6 ± 0.4 built on ambient ARPES + DFT rescaling. I would not require new high-P ARPES as a condition of acceptance, but the authors must separate measured T-linear transport from the model-dependent scattering-rate claim. Fit to a high-impact condensed-matter audience is good."},"author_rebuttal":null,"desk_editor":{"model":"grok-4.5","letter":"The useful part of this paper is the transport data, not the Planckian slogan. They grew large, stacking-fault-free, oxygen-stoichiometric La3Ni2O7 crystals (STEM, EDS, synchrotron Am2m refinement), measured absolute ρ_ab and ρ_c under hydrostatic pressure by the Montgomery method on multiple pieces, and mapped two DW anomalies with opposite pressure slopes plus zero-resistance SC that appears only after both are gone. That is the first quantitative anisotropic P–T diagram for this compound and will be cited as benchmark numbers.\n\nWhat they do well: multi-crystal reproducibility (2#-a, d, e) plus a polycrystal comparison; clear definitions of T1, T2, Tc onset/zero from ρ and dρ/dT with extended-data figures; the low-T anisotropy jump across the ~8–10 GPa ortho–tetra boundary is cleanly shown and reasonably tied to DW stacking rather than bare bond-angle change. Residual resistivities are low enough that the T-linear slope at 18–20 GPa is believable.\n\nSoft spots, in proportion. Sample-to-sample pressure offsets exist (2#-e lags 2#-a by a few GPa), so absolute P values carry the usual cubic-anvil uncertainty; they are honest about it. The structural boundary itself is cited to an unpublished Sasaki et al. note—annoying but not fatal once the transport signatures are in hand. The Planckian half of the abstract is weaker: α = 1.6 ± 0.4 is assembled from ambient ARPES kF/vF, a DFT-motivated 20 % vF boost at 20 GPa, and the Bruin multi-band formula. High-P FS parameters are unknown, so the number can easily move by a factor of two. T-linear ρ itself is solid; the claim that the scattering rate is Planckian is an order-of-magnitude statement, not a precision result. That is a minor over-sell, not a load-bearing flaw.\n\nCitation pattern is normal for a fast-moving nickelate paper; methods are standard and documented. For anyone working on nickelate SC, DW competition, or strange-metal transport this is required reading. I would send it to referees without hesitation; the data deserve the scrutiny and will survive it.","headline":"Clean single-crystal anisotropic transport and a reproducible DW/SC phase diagram are the real advance; the Planckian α is a secondary, model-dependent add-on.","tokens_in":26066,"tokens_out":613,"would_cite":true,"duration_ms":13857,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["74.70.-b","74.62.Fj","74.25.F-","71.45.Lr"],"model":"grok-4.5","headline":"Superconductivity in bilayer La3Ni2O7 emerges with zero resistance only after two density-wave orders are fully suppressed, from a T-linear strange-metal state at the Planckian limit.","keywords":["La3Ni2O7","bilayer nickelate","density-wave order","Planckian dissipation","strange metal","anisotropic transport","high-pressure superconductivity","Ruddlesden-Popper"],"falsifier":"A high-pressure measurement of the Fermi surface and velocities (for example ARPES or quantum oscillations near 20 GPa) that, when inserted into the same multi-band Drude formula, yields a Planckian coefficient α far from order one, or cleaner crystals in which clear density-wave anomalies persist through a true zero-resistance superconducting state.","tokens_in":25846,"feed_emoji":"⚡","tokens_out":1133,"duration_ms":37510,"temperature":0.7,"pith_summary":"This paper maps how charge and spin density-wave orders, anisotropic resistivity, and superconductivity evolve together under pressure in high-quality La3Ni2O7 single crystals. Using absolute in-plane and out-of-plane transport, it shows two distinct density-wave anomalies with opposite pressure trends, a sharp rise in low-temperature resistivity anisotropy across the orthorhombic-to-tetragonal transition, and superconductivity that appears only once those density-wave signatures are gone. Above Tc the normal-state resistivity is linear in temperature over a wide range, and the inferred scattering rate sits near the Planckian bound. The work supplies the missing quantitative transport backbone—absolute resistivities, anisotropy, and scattering rate—for a material whose superconductivity had been hard to pin down because of crystal quality and sample-to-sample scatter. A sympathetic reader cares because it places this nickelate in the same strange-metal family as other unconventional superconductors and ties the superconducting dome to the collapse of robust density-wave order.","feed_headline":"Nickelate SC appears only after density waves vanish","feed_subtitle":"Pressure kills two orders and leaves a T-linear metal at the Planckian scattering limit","key_machinery":"The high-precision pressure–temperature transport phase diagram built from absolute in-plane (ρ_ab) and out-of-plane (ρ_c) resistivities—including Montgomery-method anisotropy—on large, homogeneous bilayer crystals free of oxygen vacancies and Ruddlesden–Popper intergrowths. That map resolves T1 and T2, tracks their suppression, and supplies the resistivity slope used to extract the Planckian coefficient α.","core_discovery":"On oxygen-stoichiometric, stacking-fault-free La3Ni2O7 single crystals, high-pressure transport establishes a precise pressure–temperature phase diagram in which two density-wave anomalies (T1 and T2) have contrasting pressure dependences, the structural transition strongly enhances low-T resistivity and its anisotropy via modified density-wave order, and zero-resistance superconductivity emerges only near the boundary where both density-wave phases are fully suppressed. Above Tc the resistivity is T-linear over a wide range and the scattering rate falls in the Planckian regime, so robust density-wave correlations and Planckian dissipation are defining features of the material.","pith_inferences":["If density-wave fluctuations survive as the pairing glue after long-range order is gone, high-pressure inelastic probes should still see soft charge or spin modes inside the superconducting dome.","The large low-T anisotropy jump suggests interlayer decoupling analogous to stripe cuprates; c-axis coherence length or Josephson plasma data under pressure would test that analogy directly.","Reproducing α with pressure-tuned carrier density (rather than only bandwidth rescaling) would tighten or refute the Planckian assignment without new spectroscopies.","The same single-crystal protocol applied to related bilayer or trilayer nickelates should reveal whether Planckian strange metallicity is universal once density waves are suppressed."],"forward_implications":["Zero-resistance superconductivity in La3Ni2O7 is confined to the tetragonal side of the phase diagram after both density-wave anomalies disappear.","The normal state above Tc is a wide-range T-linear strange metal whose scattering rate is of order k_B T/ℏ.","The orthorhombic-to-tetragonal transition mainly boosts low-temperature transport anisotropy by changing density-wave order (possibly c-axis stacking), not by simple band hybridization alone.","Absolute resistivities and anisotropy values become reliable benchmarks for theory of bilayer nickelates under pressure.","Sample-to-sample pressure offsets can shift onsets, but the overall hierarchy—density waves first, then strange metal and superconductivity—is intrinsic."],"fun_headline_variants":["La3Ni2O7 SC emerges only after both density waves vanish","Pressure kills twin density waves, leaves Planckian T-linear metal","Two density-wave orders yield to zero-resistance nickelate SC","Structural shift boosts resistivity anisotropy before SC appears","Planckian dissipation and robust density waves define La3Ni2O7"],"cache_read_input_tokens":16512,"weakest_assumption_plain":"The claim that scattering sits at the Planckian limit depends on converting the measured resistivity slope into a scattering rate with ambient-pressure Fermi-surface parameters scaled by a theoretical high-pressure bandwidth increase.","fun_headline_variants_meta":{"raw":{"variants":["La3Ni2O7 SC emerges only after both density waves vanish","Pressure kills twin density waves, leaves Planckian T-linear metal","Two density-wave orders yield to zero-resistance nickelate SC","Structural shift boosts resistivity anisotropy before SC appears","Planckian dissipation and robust density waves define La3Ni2O7"]},"model":"grok-4.5","effort":"low","cost_usd":0.003513,"raw_usage":{"total_tokens":1234,"prompt_tokens":864,"num_sources_used":0,"completion_tokens":72,"cost_in_usd_ticks":35128000,"prompt_tokens_details":{"text_tokens":864,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":298,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":864,"tokens_out":72,"duration_ms":6048,"temperature":1.0,"reasoning_tokens":298,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-07-30T14:46:43.918070+00:00","model_set":{"reader":"grok-4.5"},"falsifier":"A high-pressure measurement of the Fermi surface and velocities (for example ARPES or quantum oscillations near 20 GPa) that, when inserted into the same multi-band Drude formula, yields a Planckian coefficient α far from order one, or cleaner crystals in which clear density-wave anomalies persist through a true zero-resistance superconducting state.","supporting_citations":[],"review_version":1}