{"id":"37804fe5-b917-4063-acae-6458dd03b8e7","arxiv_id":"2607.01302","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":6.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":0,"one_line_summary":"Bulk crystal with enforced unidirectional AA stacking of NbS2 layers exhibits Ising superconductivity exceeding the Pauli limit and a field-induced anomalous metallic state.","lead":"Researchers synthesized a bulk Sr0.75ClNbS2 crystal using a Sr-Cl network to force all NbS2 layers into unidirectional AA stacking, breaking inversion symmetry and preserving Ising spin-orbit coupling throughout the 3D material. This creates a macroscopic platform that mimics isolated monolayer electronics for studying exotic superconductivity.","discovery_kind":"unclear","skeptic_critique":{"model":"grok-4.3","headline":"Whether Sr-Cl network produces uniform, defect-free AA stacking (vs. mixed domains or other changes) is unverified at atomic scale","rationale":"The reader's weakest assumption directly identifies the same structural prerequisite that must hold for the monolayer-like electronic environment to exist throughout the bulk; the provided abstract supplies no independent atomic-scale confirmation, so the concern remains load-bearing and the UNVERDICTED status is unchanged.","tokens_in":1821,"tokens_out":298,"duration_ms":20265,"concrete_test":"Acquire atomic-resolution HAADF-STEM images or single-crystal XRD with full stacking-sequence refinement on multiple regions; if any AB or mixed domains are detected at >1 % level, the uniform noncentrosymmetric bulk claim is falsified.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim requires that the planar Sr-Cl network drives a complete, global reorganization of every NbS2 layer from native AB to unidirectional AA stacking, thereby breaking inversion symmetry uniformly so that local Ising SOC fields add rather than cancel. If stacking faults, AB domains, or intercalation-induced disorder persist, the spin-split bands would remain locally cancelled in portions of the crystal and the observed quasi-2D transport (γ ≈ 77, Hc2∥ > Pauli limit) could instead arise from doping gradients, partial decoupling, or defect scattering. The abstract and transport/band-structure data alone do not rule out these alternatives.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.3","summary":"The manuscript reports synthesis of bulk Sr0.75ClNbS2 featuring unidirectional parallel AA stacking of NbS2 layers enforced by a planar Sr-Cl network, converting native centrosymmetric 2H-NbS2 into a noncentrosymmetric D3h crystal that replicates the electronic environment of an isolated monolayer. This is claimed to preserve strong Ising SOC and spin-split bands throughout the bulk, yielding extreme superconducting anisotropy (γ ≈ 77), in-plane Hc2 ≈ 10.65 T exceeding the Pauli limit, clean-limit superconductivity, a field-induced anomalous metallic state with vanishing Hall response, and corroborating band-structure data.","tokens_in":1983,"tokens_out":451,"duration_ms":37837,"significance":"If the uniform defect-free AA stacking and resulting global symmetry breaking are established, the work provides a new route to realizing quasi-2D Ising superconductivity and related phases in macroscopic bulk crystals via stacking-geometry engineering, with potential generality to other van der Waals systems.","major_comments":[{"comment":"Abstract: the central claim that the planar Sr-Cl network drives a complete, global reorganization from native AB to unidirectional AA stacking (preventing cancellation of local Ising fields) is load-bearing for interpreting the quasi-2D transport (γ ≈ 77, Hc2 exceeding Pauli limit) as arising from persistent monolayer-like SOC rather than defects or partial decoupling; however, no atomic-resolution data (e.g., STEM or high-resolution XRD ruling out stacking faults or mixed domains) are referenced to confirm uniformity across the crystal.","section":"Abstract"},{"comment":"Abstract (transport and band-structure claims): key quantitative results (anisotropy ~77, Hc2 ~10.65 T, clean-limit behavior, vanishing Hall response) are stated without reference to raw data, error bars, fitting procedures, or specific figures/sections detailing how these were extracted; this directly affects the strength of the evidence for high crystalline quality and the anomalous metallic state.","section":"Abstract"}],"minor_comments":[],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for their careful reading of the manuscript and for highlighting these important points regarding evidence for stacking uniformity and data presentation. We respond to each major comment below.","responses":[{"response":"We agree that direct atomic-resolution confirmation of uniform, defect-free AA stacking is essential to support the interpretation of persistent monolayer-like Ising SOC in the bulk. The current manuscript relies on bulk diffraction and transport signatures, but does not yet include the requested STEM or high-resolution XRD data. In the revised manuscript we will add these measurements to explicitly rule out stacking faults or mixed domains.","revision_made":"yes","referee_comment":"[Abstract] Abstract: the central claim that the planar Sr-Cl network drives a complete, global reorganization from native AB to unidirectional AA stacking (preventing cancellation of local Ising fields) is load-bearing for interpreting the quasi-2D transport (γ ≈ 77, Hc2 exceeding Pauli limit) as arising from persistent monolayer-like SOC rather than defects or partial decoupling; however, no atomic-resolution data (e.g., STEM or high-resolution XRD ruling out stacking faults or mixed domains) are referenced to confirm uniformity across the crystal."},{"response":"We concur that the abstract and main text should provide explicit pointers to the supporting data and analysis methods. In the revised manuscript we will add direct references to the relevant figures, sections, and supplementary material that detail the extraction of γ, Hc2, the clean-limit analysis, error bars, fitting procedures, and the vanishing Hall response.","revision_made":"yes","referee_comment":"[Abstract] Abstract (transport and band-structure claims): key quantitative results (anisotropy ~77, Hc2 ~10.65 T, clean-limit behavior, vanishing Hall response) are stated without reference to raw data, error bars, fitting procedures, or specific figures/sections detailing how these were extracted; this directly affects the strength of the evidence for high crystalline quality and the anomalous metallic state."}],"tokens_in":1504,"tokens_out":430,"duration_ms":19331,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"The new element here is the synthesis method that uses a planar Sr-Cl network to flip native AB stacking in NbS2 layers into parallel AA across a macroscopic crystal, producing a globally noncentrosymmetric bulk sample with D3h symmetry. If the structural claim holds, this does give a scalable 3D platform that mimics monolayer Ising SOC without the usual cancellation.\n\nTransport data show extreme anisotropy around 77 and an in-plane Hc2 of 10.65 T above the Pauli limit, plus a field-induced anomalous metal with zero Hall response. Band-structure measurements are said to support the quasi-2D, layer-decoupled picture. These numbers are the concrete results worth noting.\n\nThe soft spot is exactly the one the stress-test flags: nothing in the abstract or reported measurements demonstrates that the AA stacking is complete and uniform at the atomic scale rather than mixed domains or defect-ridden. Without that, the observed anisotropy and Hc2 excess could come from doping gradients or partial decoupling instead. The abstract also skips raw data, error bars, and fitting details for the key claims.\n\nThis is for groups working on spin-orbit effects in superconductors or symmetry engineering. It is worth sending to peer review because the synthesis route and the transport signatures are specific enough to test, even if the structural interpretation needs more work.","headline":"The paper claims a bulk crystal route to persistent Ising superconductivity via Sr-Cl enforced unidirectional AA stacking in Sr0.75ClNbS2, but the abstract gives no atomic-scale proof that the stacking is uniform and defect-free enough to prevent local cancellation.","tokens_in":2535,"tokens_out":363,"would_cite":false,"duration_ms":18020,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.3","headline":"Unidirectional AA stacking in bulk Sr0.75ClNbS2 creates persistent Ising superconductivity with an in-plane critical field above the Pauli limit.","keywords":["Ising superconductivity","unidirectional stacking","NbS2","anomalous metallic state","spin-orbit coupling","noncentrosymmetric crystal","bulk superconductor","layered materials"],"falsifier":"High-resolution X-ray diffraction or scanning tunneling microscopy that reveals persistent domains of AB stacking or retained inversion symmetry in the bulk would show the reorganization is incomplete and falsify the claim that the AA stacking alone produces the monolayer-like behavior.","tokens_in":2733,"feed_emoji":"","tokens_out":754,"duration_ms":29295,"temperature":0.7,"pith_summary":"The paper shows that a planar Sr-Cl network can force every NbS2 layer in a bulk crystal into the same parallel AA orientation instead of the usual alternating AB arrangement. This global change breaks inversion symmetry throughout the three-dimensional material and stops neighboring layers from canceling each other's local Ising spin-orbit fields. The result is a bulk crystal whose electronic bands remain spin-split and whose superconductivity exhibits the strong anisotropy and high critical fields normally seen only in isolated monolayers. Magnetotransport data further reveal a magnetic-field-induced metallic state that shows finite resistance yet zero Hall response. The work demonstrates that deliberate layer reorganization can embed two-dimensional quantum behavior inside macroscopic crystals.","feed_headline":"Unidirectional stacking yields bulk Ising superconductor above Pauli limit","feed_subtitle":"Sr-Cl network forces parallel AA layers throughout NbS2 crystal, preserving monolayer spin-orbit splitting and extreme anisotropy in three d","key_machinery":"Unidirectional parallel AA stacking of NbS2 layers enforced by the planar Sr-Cl network, which globally breaks inversion symmetry and prevents cancellation of local Ising fields to reproduce monolayer electronics in bulk.","core_discovery":"The synthesis of Sr0.75ClNbS2 enforces unidirectional parallel AA stacking of all NbS2 layers via a planar Sr-Cl network, globally breaking inversion symmetry and converting the centrosymmetric 2H structure into a noncentrosymmetric D3h bulk crystal whose electronic environment matches that of an isolated monolayer; consequently strong Ising spin-orbit coupling and spin-split bands survive in three dimensions, producing extreme superconducting anisotropy, an in-plane upper critical field exceeding the Pauli limit, clean-limit superconductivity, and a novel field-induced anomalous metallic state with vanishing Hall response.","pith_inferences":["The same planar-network approach could be tested on other transition-metal dichalcogenides to create additional noncentrosymmetric bulk superconductors.","The anomalous metallic state might be compared with similar phases in electrostatically gated monolayer samples to isolate the role of stacking geometry.","Varying the Sr-Cl content could provide a route to tune the strength of the Ising spin-orbit coupling or the extent of the metallic state."],"forward_implications":["The bulk crystal exhibits superconducting anisotropy gamma approximately 77.","The in-plane upper critical field reaches approximately 10.65 T and exceeds the Pauli paramagnetic limit.","Transport signatures indicate clean-limit superconductivity consistent with high crystalline quality.","A magnetic-field-induced anomalous metallic state appears with finite dissipation yet vanishing Hall response.","Direct band-structure measurements confirm the layer-decoupled quasi-2D electronic nature."],"fun_headline_variants":["Unidirectional stacking in Sr0.75ClNbS2 enables bulk Ising pairing","Planar SrCl network reorganizes NbS2 into parallel AA structure","Noncentrosymmetric bulk crystal exhibits Ising superconductivity","Stacking reorganization preserves Ising spin orbit in bulk NbS2","Artificial unidirectional AA stacking in Sr0.75ClNbS2 superconductor"],"cache_read_input_tokens":64,"weakest_assumption_plain":"The planar Sr-Cl network produces a complete, defect-free reorganization from native AB to unidirectional AA stacking across the entire crystal, and this stacking change alone accounts for the observed quasi-2D electronic structure and transport signatures.","fun_headline_variants_meta":{"raw":{"variants":["Unidirectional stacking in Sr0.75ClNbS2 enables bulk Ising pairing","Planar SrCl network reorganizes NbS2 into parallel AA structure","Noncentrosymmetric bulk crystal exhibits Ising superconductivity","Stacking reorganization preserves Ising spin orbit in bulk NbS2","Artificial unidirectional AA stacking in Sr0.75ClNbS2 superconductor"]},"model":"grok-4.3","cost_usd":0.010861,"raw_usage":{"total_tokens":4846,"prompt_tokens":788,"num_sources_used":0,"completion_tokens":90,"cost_in_usd_ticks":108612000,"prompt_tokens_details":{"text_tokens":788,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":3968,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":788,"tokens_out":90,"duration_ms":32189,"temperature":1.0,"reasoning_tokens":3968,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-07-03T01:36:16.332935+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"High-resolution X-ray diffraction or scanning tunneling microscopy that reveals persistent domains of AB stacking or retained inversion symmetry in the bulk would show the reorganization is incomplete and falsify the claim that the AA stacking alone produces the monolayer-like behavior.","supporting_citations":[],"review_version":1}