{"id":"e18ac247-1a13-4af5-8ebe-cdf9bc564340","arxiv_id":"2605.25906","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":5.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":0,"one_line_summary":"Se doping in ZrTe2 drives a transition to superconductivity coexisting with nontrivial topology, with Tc maximum of 4.8 K at x=0.15 and a mapped phase diagram from CDW to semiconductor.","lead":"Se substitution in ZrTe2 crystals induces superconductivity with Tc peaking at 4.8 K for x=0.15, alongside a phase diagram showing transition from CDW to Dirac semimetal plus SC coexistence and then to semiconductor. The work identifies ZrTe1.85Se0.15 as a possible platform for topological superconductivity due to its Z2 invariant and surface states.","discovery_kind":"new_application","skeptic_critique":{"model":"grok-4.3","headline":"Wannier interpolation between ZrTe2/ZrSe2 end points may fail to capture the correct Z2 at x=0.15 if band inversions are sensitive to local Se placement or disorder.","rationale":"The reader's weakest assumption is exactly the load-bearing step. No other part of the argument (resistivity, calorimetry, or phase-diagram mapping) can substitute for a validated topological invariant at the relevant doping. The proposed supercell check directly tests whether the interpolation artifact exists.","tokens_in":1743,"tokens_out":300,"duration_ms":23967,"concrete_test":"Construct a 2\times2\times1 supercell of ZrTe1.85Se0.15 (one Se per four Te sites), relax the structure, compute the parity eigenvalues at all TRIM points from DFT, and evaluate the Z2 invariant; if it differs from the interpolated result, the topology assignment is unreliable.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The strongest claim rests on the interpolated Hamiltonian yielding a nontrivial Z2 with protected (001) surface states at the superconducting composition ZrTe1.85Se0.15. Linear or virtual-crystal interpolation of Wannier parameters assumes that topology varies smoothly with average Se concentration, yet the Z2 invariant is determined by parity eigenvalues at the eight TRIM points; any nonlinear shift in band ordering or gap closing induced by actual atomic substitution can flip the invariant without being reproduced by the interpolation.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.3","summary":"The manuscript reports the growth of ZrTe_{2-x}Se_x single crystals via isothermal chemical vapor transport and the emergence of superconductivity upon Se substitution, with Tc reaching a maximum of 4.8 K at x=0.15. Resistive, structural, and calorimetric data are combined with ab initio calculations and Wannier Hamiltonian interpolation between ZrTe2 and ZrSe2 to construct a doping-dependent phase diagram spanning CDW, Dirac semimetal plus superconductivity, and semiconducting regimes. The central claim is that ZrTe1.85Se0.15 lies in a region of nontrivial Z2 topology with nonvanishing (001) surface states, making it a candidate platform for topological superconductivity.","tokens_in":1862,"tokens_out":512,"duration_ms":25061,"significance":"If the topological classification is robust, the work would identify an experimentally accessible doped Dirac semimetal in which superconductivity coexists with protected surface states, offering a platform to test theoretical predictions for topological superconductivity. The integration of crystal growth, multiple experimental probes, and first-principles modeling is a positive feature; however, the significance hinges on whether the interpolated Hamiltonian reliably captures the Z2 invariant inside the superconducting dome.","major_comments":[{"comment":"Abstract (phase diagram construction paragraph): the nontrivial Z2 invariant and protected (001) surface states at x=0.15 are obtained from linear/virtual-crystal Wannier interpolation between the ZrTe2 and ZrSe2 end points. Because the Z2 index is fixed by parity eigenvalues at the eight TRIM points, any nonlinear shift in band ordering or gap closing caused by actual atomic substitution or local Se placement can flip the invariant without being reproduced by the interpolation; no direct parity or Wilson-loop calculation at the interpolated composition is shown to confirm the result.","section":"Abstract / ab initio calculations section"}],"minor_comments":[{"comment":"The manuscript should specify the precise method used to extract the Z2 invariant from the interpolated Hamiltonian (e.g., parity eigenvalues versus Wilson loop) and report the parity eigenvalues at each TRIM point for the x=0.15 composition.","section":"Theory section"},{"comment":"Figure captions and text should explicitly state whether error bars on Tc, resistivity, and specific-heat data are included and how the superconducting volume fraction was estimated from calorimetry.","section":"Experimental results"}],"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 identifying a key methodological point regarding the topological classification. We respond to the major comment below and indicate the planned revision.","responses":[{"response":"We agree that the virtual-crystal Wannier interpolation constitutes an approximation and that, in principle, nonlinear band shifts or local Se disorder could alter parity eigenvalues at the TRIM points. In the calculations presented, the interpolated Hamiltonian is used to obtain the bands at x=0.15, from which the Z2 invariant is evaluated via parity eigenvalues; the interpolation shows continuous evolution without gap closure at the TRIM points, preserving the invariant of the end members. Nevertheless, to directly address the concern, the revised manuscript will include an explicit tabulation (in the supplementary information) of the parity eigenvalues at the eight TRIM points for the interpolated x=0.15 Hamiltonian, together with a short discussion of the limitations of the virtual-crystal approximation at this doping level. This addition provides the requested direct confirmation while clarifying the scope of the result.","revision_made":"yes","referee_comment":"[Abstract / ab initio calculations section] Abstract (phase diagram construction paragraph): the nontrivial Z2 invariant and protected (001) surface states at x=0.15 are obtained from linear/virtual-crystal Wannier interpolation between the ZrTe2 and ZrSe2 end points. Because the Z2 index is fixed by parity eigenvalues at the eight TRIM points, any nonlinear shift in band ordering or gap closing caused by actual atomic substitution or local Se placement can flip the invariant without being reproduced by the interpolation; no direct parity or Wilson-loop calculation at the interpolated composition is shown to confirm the result."}],"tokens_in":1427,"tokens_out":361,"duration_ms":95198,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"The main takeaway is that Se substitution in ZrTe2 induces superconductivity with a clear Tc peak of 4.8 K at x=0.15, plus a phase diagram that tracks the move from CDW through a Dirac semimetal plus SC region into a semiconductor. The ab initio plus Wannier interpolation is used to argue that ZrTe1.85Se0.15 keeps a nontrivial Z2 with (001) surface states, making it a topological SC candidate.\n\nThe experimental side is the part that holds up. Crystal growth by ICVT, resistivity, structural, and calorimetric data are presented to show how low-level Se doping alters both electronic and phonon contributions while producing the SC dome. That gives a concrete composition and doping dependence not in the earlier ZrTe2 literature.\n\nThe soft spot is the topology claim. The Z2 is obtained by interpolating the Wannier Hamiltonian between the ZrTe2 and ZrSe2 end members. This assumes smooth evolution with average concentration, yet the invariant depends on parity at TRIM points and can flip from local Se placement or disorder that linear interpolation does not capture. The stress-test note flags exactly this issue, and without disordered supercell checks or direct parity calculations at the actual x=0.15 structure the conclusion stays provisional.\n\nThis is for groups working on doped topological semimetals and candidate platforms for topological superconductivity. The experimental phase diagram is usable even if the topology part needs tightening.\n\nI would send it for peer review. The new composition and measured Tc(x) are solid enough to justify referee time, with the calculation details as the main item for scrutiny.","headline":"The paper maps superconductivity in ZrTe2-xSex with Tc max 4.8 K at x=0.15 and claims topological character, but the Z2 result from endpoint Wannier interpolation is the main uncertainty.","tokens_in":2426,"tokens_out":420,"would_cite":false,"duration_ms":30174,"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":"Substituting selenium for tellurium turns ZrTe2 into a superconductor at x=0.15 while preserving a nontrivial Z2 invariant and surface states.","keywords":["ZrTe2-xSex","topological superconductivity","Dirac semimetal","phase diagram","charge density wave","selenium substitution","superconductivity"],"falsifier":"An experimental determination that the Z2 invariant becomes trivial or that surface states on the (001) planes vanish once superconductivity sets in at x=0.15 would falsify the claim of a candidate platform for topological superconductivity.","tokens_in":2663,"feed_emoji":"","tokens_out":824,"duration_ms":30428,"temperature":0.7,"pith_summary":"The paper shows that adding small amounts of selenium to zirconium ditelluride crystals creates a superconducting state at low temperatures, with the transition temperature reaching a maximum of 4.8 kelvin when 15 percent of the tellurium is replaced. Measurements and calculations map out how the material changes from a charge density wave state through a region where Dirac semimetal behavior coexists with superconductivity, and finally to a semiconductor as more selenium is added. A sympathetic reader would care because this points to a specific composition where superconductivity appears alongside a nontrivial Z2 topological invariant and surface states on certain crystal faces.","feed_headline":"4.8 K superconductivity in ZrTe2 at 15 percent Se with preserved topology","feed_subtitle":"At this composition the material enters a regime of Dirac semimetal plus superconductivity coexistence while retaining a nontrivial Z2 invar","key_machinery":"The phase diagram constructed from resistive, structural, and thermal measurements combined with ab initio calculations and Wannier Hamiltonian interpolation between ZrTe2 and ZrSe2, which tracks the evolution of the electronic topology and its persistence into the superconducting regime.","core_discovery":"The central claim is that in the ZrTe_{2-x}Se_x series, selenium substitution drives a transition from semimetal to superconductor, with an extensive phase diagram showing coexistence between the Dirac semimetal and superconductivity up to the semiconductor phase. At x=0.15, the compound ZrTe1.85Se0.15 exhibits superconductivity with Tc=4.8 K and hosts a nontrivial Z2 invariant with nonvanishing surface states in its (001) planes, establishing it as a candidate platform for topological superconductivity.","pith_inferences":["If surface states remain gapless when the bulk becomes superconducting, the material offers a concrete setting in which to test whether topology and pairing can be combined without external fields or proximity effects.","The interpolation approach between the two end compounds supplies a practical route to scan topology across other isostructural alloy series without recomputing every intermediate composition from scratch.","Transport or tunneling measurements focused on the (001) face could directly test whether the predicted nonvanishing states survive into the superconducting regime.","The same substitution window may be worth checking in chemically related transition-metal dichalcogenides to see whether similar coexistence regions appear."],"forward_implications":["Superconductivity emerges upon Se substitution in the ZrTe2 matrix with a clear dependence of Tc on selenium concentration.","The critical temperature peaks at x=0.15 with Tc of 4.8 K.","Calorimetric data indicates modification of both electronic contribution and vibrational modes at low Se substitution.","The system transitions from charge density wave to Dirac semimetal plus superconductivity coexistence and then to semiconductor phase.","ZrTe1.85Se0.15 is identified as hosting a nontrivial Z2 invariant with nonvanishing surface states in (001) planes."],"fun_headline_variants":["ZrTe2-xSex shows 4.8 K superconductivity at x=0.15 with Z2 invariant","Coexistence of Dirac semimetal and 4.8 K superconductivity in ZrTe1.85Se0.15","Phase diagram of ZrTe2-xSex shows semimetal superconductor coexistence","ZrTe1.85Se0.15 exhibits 4.8 K SC with nontrivial Z2 and surface states"],"cache_read_input_tokens":2112,"weakest_assumption_plain":"The ab initio calculations combined with Wannier Hamiltonian interpolation between ZrTe2 and ZrSe2 correctly capture the electronic topology and its persistence into the superconducting regime.","fun_headline_variants_meta":{"raw":{"variants":["ZrTe2-xSex shows 4.8 K superconductivity at x=0.15 with Z2 invariant","Coexistence of Dirac semimetal and 4.8 K superconductivity in ZrTe1.85Se0.15","Phase diagram of ZrTe2-xSex shows semimetal superconductor coexistence","ZrTe1.85Se0.15 exhibits 4.8 K SC with nontrivial Z2 and surface states"]},"model":"grok-4.3","cost_usd":0.008961,"raw_usage":{"total_tokens":4054,"prompt_tokens":724,"num_sources_used":0,"completion_tokens":105,"cost_in_usd_ticks":89612000,"prompt_tokens_details":{"text_tokens":724,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":3225,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":724,"tokens_out":105,"duration_ms":24196,"temperature":1.0,"reasoning_tokens":3225,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-06-29T19:19:23.393581+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"An experimental determination that the Z2 invariant becomes trivial or that surface states on the (001) planes vanish once superconductivity sets in at x=0.15 would falsify the claim of a candidate platform for topological superconductivity.","supporting_citations":[],"review_version":1}