{"id":"c2657787-17cb-4bf7-a8be-9c7f87d866ee","arxiv_id":"2507.01108","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":8.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":1,"one_line_summary":"Edge-to-edge current injection into FeTe0.55Se0.45 produces a robust, drain-position-dependent conductance plateau attributed to chiral topological superconductor edge modes.","lead":"Researchers made electrical contacts that touch only the clean side edges of the superconductor FeTe0.55Se0.45 and found a flat conductance plateau that appears only when current flows edge to edge, which they attribute to protected chiral edge modes of a topological superconductor. If confirmed, this would be the first transport evidence that the material hosts chiral topological superconductivity, a long-sought ingredient for Majorana-based quantum computing.","discovery_kind":"new_method","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Central claim rests on unverified premise that current enters only through the cleaved edge and that the plateau is a 3D chiral-edge signature; neither the oxide-blocking contact model nor the 2D-to-3D theory transfer is quantitatively established.","rationale":"The strongest parts of the paper are the same-device configuration switching (plateau to zero-bias peak to Andreev double-peak structure) and the topologically trivial FeTe0.4Se0.6 controls; these rule out many trivial explanations. The plateau's disappearance near TKerr rather than Tc and its insensitivity to 8 T fields also independently support a magnetic-order-linked process. However, the central claim identifies that process as protected chiral edge modes, and that identification depends on two premises that are not independently established: edge-only current injection and the validity of 2D single-mode C-TSC theory for a 3D multi-channel sample. The paper itself flags the second premise by stating that a fully quantitative description exceeds the scope of previous single-mode models. The first premise is supported by a single cross-sectional STEM image and is in tension with the observation that top-surface contacts with comparable normal-state resistance show regular Andreev reflection. A normal-metal or degraded-superconducting shell along the plasma-etched edge could reproduce many of the reported signatures and could correlate with magnetization only through the shared magnetic transition, without requiring topological edge modes. This concern is not an accusation; it is the minimal assumption that needs empirical support before the word 'unambiguous' is justified. The proposed focused-ion-beam interruption test, or a quantitative 3D theory benchmark, would settle it. If the test shows the plateau survives edge interruption, the central claim is wrong; if it disappears and a quantitative theory matches, the claim is strongly supported. Since the paper has not performed that test, the conditional verdict is appropriate.","tokens_in":14679,"tokens_out":13462,"duration_ms":223767,"concrete_test":"Fabricate a FeTe0.55Se0.45 device in the double-edge-lead configuration, then use focused-ion-beam milling to cut a narrow insulating trench across the cleaved edge between source and drain while leaving the top surface continuous; if the conductance plateau survives this edge interruption, the signal is not mediated by the crystalline edge and the central premise fails, whereas disappearance of the plateau would confirm that the edge path is required.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Identifying the plateau as protected chiral-edge transport requires two conditions: (i) the contacts are electrically dominated by the crystalline edge, with the native oxide blocking top-surface injection; and (ii) the observed lineshape and height are those expected for C-TSC edge modes in this 3D multi-channel device. Neither condition is quantitatively established. The paper states that 'the top oxide enables transport primarily into the side' and supports this with one cross-sectional STEM image, but the same devices also use top-surface contacts (GSur) that show ordinary Andreev reflection with normal-state resistances similar to the edge contacts, so the top path is demonstrably not inert. If the Ar-plasma etching creates a normal or weakly superconducting shell along the cleaved edge, then a source and drain both touching that shell would naturally produce a low-bias excess conductance that disappears when the drain moves to the bulk; this would be a local contact effect rather than a nonlocal chiral-edge signature. The authors also concede that 'a fully quantitative description of the plateau from C-TSC edge states exceeds the scope of previous single-mode models.' Without a quantitative 3D multi-channel calculation, the claimed threshold signature—bias-independent plateau, thickness-proportional height, field insensitivity—is not uniquely tied to a Weyl or chiral state. The same-device switching and trivial-composition controls are strong evidence against ordinary Andreev processes, but they do not isolate chirality.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript reports differential-conductance measurements on FeTe0.55Se0.45 flakes with contacts placed on cleaved crystalline edges. It claims the first observation of protected, non-local transport mediated by chiral topological superconductor (C-TSC) edge modes emerging from a potential Weyl-superconducting state. The central signature is a bias-independent conductance plateau in the double-edge-lead configuration, which switches to a zero-bias conductance peak when the drain is moved to the bulk and to ordinary Andreev double-peak spectra when the source is on the top surface. The plateau is reported to be insensitive to magnetic fields up to 8 T, to vanish near the magnetization temperature TKerr ≈ 10 K rather than Tc ≈ 14.2 K, to scale with flake thickness, and to be absent in topologically trivial Fe(Te,Se) controls. The authors propose a device design in which a native oxide blocks top-surface injection so that current enters through the cleaved edge.","tokens_in":14755,"tokens_out":5775,"duration_ms":70590,"significance":"If the interpretation is correct, this is a landmark result: the first unambiguous transport demonstration of chiral topological superconductor edge states in an iron-based superconductor, with a non-local, field-robust signature that goes beyond previous point-contact zero-bias anomalies. The paper's internal controls are substantial: the same device switches between plateau, ZBCP, and Andreev double-peak configurations; the plateau is reproduced in multiple devices and laboratories; trivial-composition samples with similar Tc and magnetization do not show the plateau; and the temperature dependence tracks the Kerr signal rather than Tc. These controls make the observation unlikely to be a generic contact artifact, and the authors are appropriately cautious in calling the material a 'potential Weyl superconductor.' However, the central claim rests on two premises that are not quantitatively established: the electrical exclusivity of the edge contacts and the transfer of 2D single-mode C-TSC theory to the 3D multi-channel device. The paper would need additional experimental or theoretical support before the claim can be accepted as definitive.","major_comments":[{"comment":"The premise that current enters primarily through the cleaved edge is not quantitatively demonstrated. The text states that 'the top oxide enables transport primarily into the side' and supports this with a cross-sectional STEM image, but the same devices' top-surface contacts (GSur) show ordinary Andreev reflection with normal-state resistances similar to the edge contacts, implying the top path is electrically active. If the Ar-plasma etch creates a normal or weakly superconducting shell along the cleaved edge, two contacts on that shared shell could produce a low-bias conductance plateau that disappears when the drain is moved to the bulk, which would be a local contact effect rather than a chiral-edge signature. The trivial-composition controls do not fully resolve this unless identical etch and oxide properties are demonstrated across compositions. A quantitative injection test, such as comparing edge vs top contact resistances in the normal state or using a geometry that isolates edge current, should be provided.","section":"Device Design, Fig. 1d"},{"comment":"The authors concede that 'a fully quantitative description of the plateau from C-TSC edge states exceeds the scope of previous single-mode models.' Because the central claim is that the plateau is the specific signature of 3D multi-channel C-TSC edge modes, the paper should provide a quantitative model or a concrete falsifiable prediction that distinguishes the proposed mechanism from a plasma-damaged edge shell or multi-channel Andreev processes. Without such a calculation, the observed combination of bias independence, thickness scaling, and field insensitivity is not uniquely tied to a chiral topological state. A transport calculation for a 3D multi-channel chiral edge, even a minimal lattice model, or a predicted quantized or stepped conductance would materially strengthen the identification.","section":"Non-Local Response"},{"comment":"The temperature argument for topological protection is not fully controlled. The plateau width is approximately ±0.4 mV, so by T ≈ 10 K the thermal energy (≈0.86 meV) already exceeds the feature width; a non-topological narrow conductance feature would also be thermally washed out near 10 K. The correlation with the Kerr signal is suggestive, but to conclude that the plateau is 'protected from thermal smearing' unless magnetic order is suppressed, the authors should compare the observed temperature broadening to an explicit model of the edge-plateau lineshape at finite temperature, and ideally to a trivial narrow-feature control with the same width.","section":"Temperature Evolution and Magnetic Order, Fig. 3"}],"minor_comments":[{"comment":"The first paragraph contains a typo: 'An promising approach' should read 'A promising approach.'","section":"Introduction"},{"comment":"The notation Gij,mn is introduced, but the main text does not clearly state the sign convention and which indices correspond to current versus voltage leads; please define this explicitly in the main text and in the Fig. 2 caption.","section":"Non-Local Response and Fig. 2"},{"comment":"The sentence 'the ZBCP is not entirely understood may be explained by several mechanisms... such as Andreev edge states (AES)' is grammatically incomplete, and the abbreviation AES is not defined; please revise and define all abbreviations.","section":"Non-Local Response"},{"comment":"The abstract claims 'first observation of protected, non-local transport,' while the Discussion claims 'first unambiguous, long-sought evidence of C-TSC edge states'; harmonize these claims given the prior reports of helical hinge zero modes cited in Ref. 48.","section":"Discussion and Outlook"}],"recommendation":"major_revision","confidential_remarks":"This is a high-visibility claim with strong internal controls and reproducibility across laboratories. I do not recommend rejection because the same-device switching and trivial-composition controls are compelling; however, the edge-injection model and the 2D-to-3D theory transfer are load-bearing and need to be made quantitative. The editors may wish to secure a referee with specific expertise in point-contact spectroscopy and plasma-etched contacts on iron-based superconductors to assess the contact model."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The thing you should know up front: this is a serious experimental paper, and the core observation is probably real — a conductance plateau that appears only when source and drain both touch a cleaved edge of FeTe0.55Se0.45, turns into a zero-bias peak when the drain goes to the top surface, and survives 8 T and thermal smearing until the Kerr magnetization drops at ~10 K, not at Tc. What is genuinely new is the drain-position dependence and the same-device switching between plateau, ZBCP, and Andreev double-peak, plus control samples with similar Tc and magnetism but trivial band structure. If the plateau is what they claim, it is the first clean non-local transport signature of chiral edge modes in an iron-based superconductor.\n\nCredit where due: the internal controls are strong. The configuration switching is on the same flake. The trivial-composition controls are the right kind of control. The correlation with the magnetization temperature is falsifiable and not something you can fit away. They also openly concede that a quantitative description needs 3D multi-channel theory, which the single-mode models don't provide.\n\nNow the soft spots. The load-bearing premise is that the Ar-etched contacts are electrically dominated by the cleaved edge, with the native oxide blocking the top surface. The evidence is one cross-sectional STEM image and the statement that the top oxide enables transport primarily into the side. But the same devices have top-surface contacts that show ordinary Andreev reflection at similar resistances, so the top path is demonstrably not inert. If the etch leaves a normal or altered superconducting shell along the edge, two edge contacts could give a low-bias excess conductance that would also look non-local when the drain moves to the bulk. The trivial controls do argue against a plain shell short, but they don't eliminate the possibility of a composition-dependent shell.\n\nThe second soft spot is the theory link. The plateau height and thickness scaling are only qualitative, and the authors admit the single-mode C-TSC predictions don't directly apply to their 3D multi-channel devices. So the chiral-edge interpretation is plausible, but not uniquely pinned by the data. Minor issues: no error bars or device yield statistics, and the plateau is not quantized.\n\nOverall, this paper deserves a serious referee. The question is not whether the observation is real — it is — but whether the contact geometry and theory transfer can be tightened enough to support the 'first unambiguous' language. I'd send it out with a request for quantitative contact characterization (oxide transmission, edge-shell conductance) and, ideally, a 3D model calculation. If those come back clean, this becomes a landmark transport result.","headline":"A well-controlled, likely real observation of a non-local conductance plateau, but the chiral-edge interpretation rests on a contact geometry premise that the paper does not fully close.","tokens_in":15616,"tokens_out":3513,"would_cite":true,"duration_ms":43413,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"This paper reports the first observation of edge-mode-mediated nonlocal transport in the potential Weyl superconductor FeTe0.55Se0.45.","keywords":["topological superconductivity","chiral topological superconductor edge states","nonlocal transport","iron-based superconductor","FeTe0.55Se0.45","time-reversal symmetry breaking","differential conductance plateau","Andreev reflection"],"falsifier":"Measure the plateau in a device where the top surface is made deliberately conducting by removing the oxide while keeping the same edge-contact geometry; if the plateau persists unchanged, the claim that transport is edge-mediated is falsified. Alternatively, reproduce the double-edge-lead measurement on a topologically trivial FeTe0.4Se0.6 flake with identical plasma etching; a plateau there would show the signal is an etching artifact rather than a topological signature.","tokens_in":14297,"feed_emoji":"🧲","tokens_out":5936,"duration_ms":66991,"temperature":0.7,"pith_summary":"The paper argues that a bias-independent conductance plateau appearing only when two contacts sit on the same sharp crystalline edge of FeTe0.55Se0.45 is the long-sought transport signature of chiral topological superconductor edge states. The plateau disappears and becomes a zero-bias peak when the drain moves to the bulk, showing the transport is nonlocal and mediated by the edge rather than by local Andreev reflection. The signal is unaffected by magnetic fields up to 8 T, vanishes at the magnetic ordering temperature near 10 K rather than at the superconducting transition near 14.2 K, and is absent in topologically trivial FeTe0.4Se0.6 with similar superconducting and magnetic properties. If correct, this constitutes the first unambiguous demonstration of protected chiral edge transport in an iron-based superconductor and a new way to detect topological superconductivity.","feed_headline":"First edge-mode transport plateau found in FeTe0.55Se0.45","feed_subtitle":"Plateau survives 8 T, dies at 10 K magnetic order, only with edge-to-edge contacts.","key_machinery":"The mechanism is the chiral topological superconductor edge state: a propagating, gapless channel along the side surface whose self-Hermitian property suppresses normal reflection and lets current enter, travel ballistically, and leave resonantly. The experiment's enabling tool is a contact geometry that reads this channel: argon-plasma etching that keeps the native oxide on the top surface while making ohmic contact to a preselected straight crystalline edge, so the measured differential conductance is dominated by the edge.","core_discovery":"The central claim is that resonant charge injection, ballistic propagation, and extraction through the edge modes of a Weyl-superconducting phase produce a distinctive nonlocal conductance plateau in FeTe0.55Se0.45. The plateau appears only in the double-edge-lead configuration on topologically nontrivial samples; switching the drain to the surface turns it into a zero-bias conductance peak, and placing both source and drain on the surface yields ordinary Andreev double-peak spectra. Its height scales roughly with flake thickness, consistent with multiple edge channels, and its temperature dependence tracks the spontaneous magnetization rather than the superconducting gap. The authors present this correlation, together with device reproducibility, absence in trivial samples, and insensitivity to 8 T fields, as evidence that the plateau is carried by topologically protected edge states rather than by Andreev bound states, helical hinge modes, or heating artifacts.","pith_inferences":["A clean test of the edge-mediation claim would be to measure the same device before and after deliberately removing the top oxide; if the plateau persists with a fully conducting top surface, the interpretation in terms of exclusive edge injection would be harder to maintain.","The near-linear growth of plateau height with flake thickness suggests a stacked-layer picture in which each superconducting layer adds a transport channel; thinning the flake and tracking the plateau height could test this directly.","If the edge modes are Majorana in nature, the same geometry should also show quantized thermal conductance, a measurable prediction the paper does not make.","The same double-edge-lead geometry could be applied to other candidate chiral superconductors to look for a plateau with the same magnetic-field and temperature robustness."],"forward_implications":["The plateau can serve as a routine transport diagnostic for chiral topological superconductor edge states in FeTe0.55Se0.45 and related iron-based superconductors.","Because the signal survives source-drain separations of 5 micrometers, more than a thousand times the coherence length, edge-mediated nonlocal transport could route current through protected channels in future devices.","The correlation with magnetization implies the edge states exist only in the time-reversal-symmetry-broken phase, so superconductivity alone does not guarantee the protected transport signature.","A quantitative model of the multi-channel, three-dimensional plateau remains to be built; the experiment constrains such models by tying plateau width to magnetization and plateau height to flake thickness."],"supporting_citations":[{"why":"Predicts resonant-crossed Andreev reflection in topological superconductors, the theoretical basis for edge-mediated nonlocal current injection and extraction.","marker":"[14]"},{"why":"Predicts quantum perfect crossed Andreev reflection in topological junctions, underlying the expected conductance plateau from edge modes.","marker":"[15]"},{"why":"Shows anomalous nonlocal conductance as a fingerprint of chiral Majorana edge states, the central signature the experiment targets.","marker":"[16]"},{"why":"Establishes the self-Hermitian mechanism by which chiral edge modes suppress normal reflections.","marker":"[13]"},{"why":"Reports bulk time-reversal symmetry breaking whose temperature scale the plateau's suppression at about 10 K is matched against.","marker":"[38]"},{"why":"Establishes the nontrivial topological band structure of Fe(Te,Se), the topological ingredient the plateau is claimed to require.","marker":"[31]"},{"why":"Provides the local Andreev reflection spectra and superconducting gap scale used as the trivial reference.","marker":"[43]"},{"why":"Documents the earlier zero-bias anomaly in Fe(Te,Se) that this work distinguishes from the nonlocal plateau.","marker":"[48]"},{"why":"Shows the rapid oxidation of thin Fe(Te,Se), motivating the oxide-blocking edge-contact design.","marker":"[49]"}],"fun_headline_variants":["Edge-mode plateau in Weyl superconductor FeTeSe","Protected edge transport plateau in FeTe0.55Se0.45","Nonlocal edge modes signal Weyl superconductivity","Edge modes carry nonlocal current in FeTe0.55Se0.45"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The experiment assumes the plasma-etched contacts are electrically dominated by the cleaved crystalline edge, with the native oxide blocking top-surface injection; if that oxide conducts or the etched near-surface region has altered superconducting properties, the configuration-dependent plateau could arise from non-topological effects.","fun_headline_variants_meta":{"raw":{"variants":["Edge-mode plateau in Weyl superconductor FeTeSe","Protected edge transport plateau in FeTe0.55Se0.45","Nonlocal edge modes signal Weyl superconductivity","Edge modes carry nonlocal current in FeTe0.55Se0.45"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000391,"raw_usage":{"total_tokens":2041,"prompt_tokens":916,"completion_tokens":1125,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":532,"completion_tokens_details":{"reasoning_tokens":1051}},"tokens_in":532,"tokens_out":1125,"duration_ms":10543,"temperature":1.0,"reasoning_tokens":1051,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-06T21:01:58.282700+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the plateau in a device where the top surface is made deliberately conducting by removing the oxide while keeping the same edge-contact geometry; if the plateau persists unchanged, the claim that transport is edge-mediated is falsified. Alternatively, reproduce the double-edge-lead measurement on a topologically trivial FeTe0.4Se0.6 flake with identical plasma etching; a plateau there would show the signal is an etching artifact rather than a topological signature.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Predicts resonant-crossed Andreev reflection in topological superconductors, the theoretical basis for edge-mediated nonlocal current injection and extraction."},{"cited_title":"& Sun, Q.-F","cited_arxiv_id":null,"evidence_quote":"Predicts quantum perfect crossed Andreev reflection in topological junctions, underlying the expected conductance plateau from edge modes."},{"cited_title":"& Manske, D","cited_arxiv_id":null,"evidence_quote":"Shows anomalous nonlocal conductance as a fingerprint of chiral Majorana edge states, the central signature the experiment targets."},{"cited_title":"& Beenakker, C","cited_arxiv_id":null,"evidence_quote":"Establishes the self-Hermitian mechanism by which chiral edge modes suppress normal reflections."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Establishes the nontrivial topological band structure of Fe(Te,Se), the topological ingredient the plateau is claimed to require."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Documents the earlier zero-bias anomaly in Fe(Te,Se) that this work distinguishes from the nonlocal plateau."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Shows the rapid oxidation of thin Fe(Te,Se), motivating the oxide-blocking edge-contact design."}],"review_version":1}