{"id":"478517ac-26af-477b-aecb-c0f9a9bc7742","arxiv_id":"2606.04956","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":4.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":0,"one_line_summary":"Nb0.85Sc0.15 films deposited by Nb/Sc co-sputtering exhibit Tc = 6.35 K, Jc up to 2.5 MA/cm², Hc2(0) = 3.2 T, and coherence length 10.1 nm.","lead":"The paper describes magnetron co-sputtering to make NbSc alloy films and reports their measured superconducting properties including a peak Tc of 6.35 K at ~15% Sc. Engineers working on low-temperature electronics may find the reported critical current and field values relevant for device design.","discovery_kind":"unclear","skeptic_critique":{"model":"grok-4.3","headline":"Auger-determined Sc concentration may reflect surface rather than bulk film composition","rationale":"The reader’s weakest assumption is identical to the identified concern. Because the measurement method is surface-sensitive and no bulk confirmation is referenced in the supplied abstract, the central composition–Tc correlation remains unverified. This moves the verdict from UNVERDICTED to CONDITIONAL pending the depth-profile or independent-composition check; no other internal inconsistency was apparent from the given text.","tokens_in":1740,"tokens_out":347,"duration_ms":26971,"concrete_test":"Acquire Auger depth profiles (Ar+ sputtering) on the same Nb0.85Sc0.15 film used for Tc measurement; if the Sc/Nb ratio changes by >3 at.% between the top 5 nm and the film interior, recompute the Tc-vs-x plot using the interior value and check whether the maximum remains at the originally reported 15 %.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The headline result ties the observed Tc maximum (6.35 K) specifically to ~15 at.% Sc. Auger spectroscopy is surface-sensitive (typical information depth 1–5 nm for Nb/Sc), while the microbridge films are 30 nm thick. The abstract and claim provide no mention of Ar-ion depth profiling, calibration against standards (e.g., RBS or EDS), or cross-check against XRD-derived lattice parameters. If surface segregation, oxidation, or preferential sputtering occurs, the reported concentration does not correspond to the volume-averaged composition that sets Tc. This is the load-bearing link because the entire Tc-vs-x curve and the “optimal 15 %” statement rest on it.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.3","summary":"The manuscript reports the synthesis of Nb_{1-x}Sc_x thin films by magnetron co-sputtering from separate Nb and Sc targets, followed by structural characterization (XRD, XRR) and superconducting transport/magnetic measurements on 30 nm microbridges. The central experimental result is a maximum Tc of 6.35 K at ~15 at.% Sc (determined by Auger spectroscopy), together with Jc up to 2.5 MA/cm², Hc2(0) = 3.2 T, D = 1.1 cm²/s and ξ_GL = 10.1 nm; the material is presented as promising for cryogenic electronics.","tokens_in":1868,"tokens_out":483,"duration_ms":20888,"significance":"If the composition-Tc correlation is reliable, the work adds an experimental data point on Nb-based alloy films with moderately enhanced Tc and usable critical current density. The measurements employ standard techniques (four-probe transport, magnetoresistance, perpendicular-field magnetization) and report concrete numbers that could be useful for device design, but the absence of bulk-composition verification limits the strength of the composition-dependent claim.","major_comments":[{"comment":"Abstract: The headline claim that Tc reaches its maximum (6.35 K) specifically at ~15 % Sc rests entirely on Auger spectroscopy. Auger is surface-sensitive (typical probe depth 1–5 nm) while the microbridge films are 30 nm thick; the text provides no Ar-ion depth profiling, calibration against bulk standards (RBS/EDS), or cross-check with XRD lattice parameters. If surface segregation or oxidation is present, the reported concentration does not correspond to the volume-averaged composition that sets Tc, rendering the Tc-vs-x curve and the “optimal 15 %” statement unsupported.","section":"Abstract"}],"minor_comments":[{"comment":"Abstract: Typo “concentarions” should read “concentrations”.","section":"Abstract"},{"comment":"Abstract: The statement that “the technology has been developed” is vague; a brief description of the co-sputtering power ratios or deposition rates used to achieve the different Sc contents would improve reproducibility.","section":"Abstract"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for the careful review and constructive feedback on our manuscript. We address the single major comment below.","responses":[{"response":"We agree that Auger spectroscopy is surface-sensitive (probe depth typically 1-5 nm) and that the manuscript does not report Ar-ion depth profiling, RBS/EDS calibration, or explicit cross-checks with XRD lattice parameters. The reported ~15 at.% Sc value is therefore based on surface measurements, and the possibility of segregation or oxidation affecting the volume-averaged composition cannot be ruled out from the presented data. In the revised version we will (i) qualify the abstract statement to read that the maximum Tc of 6.35 K was observed for the sample whose surface composition (by AES) was approximately 15 at.% Sc, (ii) add a brief methods paragraph noting the surface sensitivity of AES and the assumption of uniform composition supported by XRR/XRD, and (iii) explicitly state that bulk-sensitive verification would strengthen the composition-Tc correlation. These changes make the limitation transparent without altering the experimental results.","revision_made":"yes","referee_comment":"[Abstract] Abstract: The headline claim that Tc reaches its maximum (6.35 K) specifically at ~15 % Sc rests entirely on Auger spectroscopy. Auger is surface-sensitive (typical probe depth 1–5 nm) while the microbridge films are 30 nm thick; the text provides no Ar-ion depth profiling, calibration against bulk standards (RBS/EDS), or cross-check with XRD lattice parameters. If surface segregation or oxidation is present, the reported concentration does not correspond to the volume-averaged composition that sets Tc, rendering the Tc-vs-x curve and the “optimal 15 %” statement unsupported."}],"tokens_in":1475,"tokens_out":375,"duration_ms":27726,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"This paper reports fabrication of Nb1-xScx films by magnetron co-sputtering, structural checks with XRD and X-ray reflectometry, and superconducting measurements on 30 nm microbridges. They varied Sc content, saw a Tc peak of 6.35 K near 15% Sc by Auger, and give Jc up to 2.5 MA/cm², Hc2(0) of 3.2 T, plus D and ξGL for the main sample.\n\nThe work is competent on the experimental side. They cover synthesis, basic characterization, and transport plus magnetoresistance data in a usable way for this alloy. The numbers are specific and could matter for people making thin-film devices.\n\nThe soft spot is the concentration measurement. Auger spectroscopy only sees a few nm into the surface. With 30 nm films and no mention of depth profiling, standards, or cross-checks like RBS, the reported 15% may not be the average composition that actually controls Tc. That link carries the \"optimal at 15%\" statement, so it needs verification.\n\nOtherwise there are no big overclaims or circular arguments. The paper stays within what the data show.\n\nThis is for researchers working on Nb-based thin films or cryogenic electronics who need parameters for this specific composition. It is incremental but the data points are the kind that get checked in the literature.\n\nI would send it to peer review. The Auger issue is addressable with extra measurements or clarification, and the rest is solid enough to be worth referee time.","headline":"This is a straightforward experimental report on Nb-Sc thin films with concrete numbers, but the 15% Sc claim rests on Auger data that may not reflect bulk composition in 30 nm films.","tokens_in":2393,"tokens_out":402,"would_cite":false,"duration_ms":27237,"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":"Nb0.85Sc0.15 films made by magnetron co-sputtering reach a superconducting transition temperature of 6.35 K.","keywords":["NbSc","superconductor","thin film","magnetron sputtering","critical temperature","critical current density","upper critical field","coherence length"],"falsifier":"An independent bulk composition measurement on the same 6.35 K sample that finds a scandium fraction significantly different from 15 percent would falsify the reported composition optimum.","tokens_in":2667,"feed_emoji":"","tokens_out":424,"duration_ms":24991,"temperature":0.7,"pith_summary":"A co-sputtering process from separate niobium and scandium targets was used to deposit Nb1-xScx thin films with controlled composition. X-ray methods established film thickness, phase, and crystal structure, while Auger spectroscopy fixed the scandium fraction. Critical temperature measurements across samples identified a peak Tc of 6.35 K near 15 percent scandium. Microbridge transport data gave a critical current density of 2.5 MA per square centimeter, and perpendicular-field magnetometry supplied the upper critical field, diffusion coefficient, and coherence length. The alloy is presented as a candidate material for cryogenic electronics components.","feed_headline":"Nb-Sc alloy film reaches 6.35 K superconducting transition","feed_subtitle":"Co-sputtered 15 percent scandium films also deliver 2.5 MA/cm² critical current density and 10 nm coherence length.","key_machinery":"Magnetron co-sputtering from separate Nb and Sc targets that controls scandium fraction in the deposited Nb1-xScx film.","core_discovery":"The Nb0.85Sc0.15 film achieves a maximum critical temperature Tc of 6.35 K; microbridge measurements yield a critical current density of 2.5 MA/cm² while magnetic measurements give Hc2(0) = 3.2 T, D = 1.1 cm²/s, and ξGL = 10.1 nm.","pith_inferences":[],"forward_implications":[],"fun_headline_variants":["Nb0.85Sc0.15 film reaches 6.35 K Tc","NbSc microbridge critical current at 2.5 MA/cm2","Co-sputtered NbSc film has 6.35 K transition","Nb0.85Sc0.15 yields Hc2 of 3.2 T","10.1 nm coherence length in NbSc film"],"cache_read_input_tokens":2112,"weakest_assumption_plain":"The scandium concentration measured by Auger spectroscopy accurately reflects the bulk film composition that determines the superconducting transition temperature.","fun_headline_variants_meta":{"raw":{"variants":["Nb0.85Sc0.15 film reaches 6.35 K Tc","NbSc microbridge critical current at 2.5 MA/cm2","Co-sputtered NbSc film has 6.35 K transition","Nb0.85Sc0.15 yields Hc2 of 3.2 T","10.1 nm coherence length in NbSc film"]},"model":"grok-4.3","cost_usd":0.007627,"raw_usage":{"total_tokens":3441,"prompt_tokens":727,"num_sources_used":0,"completion_tokens":96,"cost_in_usd_ticks":76265500,"prompt_tokens_details":{"text_tokens":727,"audio_tokens":0,"image_tokens":0,"cached_tokens":64},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":2618,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":727,"tokens_out":96,"duration_ms":26557,"temperature":1.0,"reasoning_tokens":2618,"cache_read_input_tokens":64,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-06-28T03:43:46.689667+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"An independent bulk composition measurement on the same 6.35 K sample that finds a scandium fraction significantly different from 15 percent would falsify the reported composition optimum.","supporting_citations":[],"review_version":1}