{"id":"04b719b9-d8fb-4410-931a-61ba6dd5402d","arxiv_id":"2506.21160","paper_version":3,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":5,"one_line_summary":"Scanning thermoelectric microscopy of a single skyrmion, together with analytic modeling of the anomalous Nernst, planar Nernst, and anisotropic magneto-thermopower contributions, yields a spatial voltage pattern that can distinguish Bloch from Néel skyrmions.","lead":"This paper maps the tiny thermoelectric voltages that a single magnetic skyrmion produces when a heated probe touches it, then compares the pattern to simulations of two skyrmion types. The comparison suggests a standard lab microscope could tell Bloch and Néel skyrmions apart, which would help screen materials for skyrmion devices.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Fingerprinting claim lacks a positive control: no Bloch skyrmion was measured, and S∥−S⊥ is inferred from the same image used for the Néel classification.","rationale":"The reader identified analytic texture fidelity as the weakest assumption; I agree that is a risk, but the more load-bearing point is the absence of a positive control and the circularity of inferring S∥−S⊥ from the same image used to classify the texture. The model itself is internally consistent: Eq. 3b–3c show that for an ideal radial (Néel) texture, m_xm_y and m_y^2 have different angular patterns than for a tangential (Bloch) texture when (S∥−S⊥)≠0, so a distinction is theoretically possible. That part of the argument holds. What is not established is that the technique can actually fingerprint in practice: (i) no Bloch-type skyrmion has been measured; (ii) the only experimental classification uses the same image to fix S∥−S⊥ and then to assign the texture; (iii) Fig. 4 shows that mixed states produce intermediate signals, so the map-to-texture inversion is degenerate. These are addressable with feasible experiments, so I do not recommend rejection. The paper's honest caveats on p.10 about non-circular skyrmions and magnetostatic distortions, and the final limitation that helicity cannot be determined from SThEM alone, are to its credit; the title should perhaps be read as modelling-guided SThEM fingerprinting. The reader's CONDITIONAL verdict already captures this; no adjustment is needed.","tokens_in":13073,"tokens_out":10202,"duration_ms":124919,"concrete_test":"Perform SThEM on a lamella of FeGe (or exfoliated Fe3GaTe2) in which the same skyrmions are independently identified as Bloch-type by Lorentz TEM or NV magnetometry; feed the measured or Tomographic/LTEM-reconstructed texture into the thermoelectric model of Eq. 2–3 with independently measured S∥ and S⊥ on the same material, and check whether the predicted voltage map matches the measured SThEM image and clearly differs from the simulated Néel map. A mismatch, or an inability to separate the two classes above the ~15 nV noise floor, would falsify the fingerprinting claim.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim is that SThEM can distinguish Bloch from Néel skyrmions. In the model, the only spin-texture-dependent distinction comes from the PNE/AMTP terms in Eq. 3b–3c, which are proportional to (S∥−S⊥); when S∥=S⊥ the simulated images for the two textures are identical. The experimental support consists of a single SThEM image of one skyrmion in a Pt/Co/Ir multilayer known to host Néel skyrmions. The authors infer S∥−S⊥ ≈ 0.25 µV/K from the shape of that same image (the Yin–Yang-esque lower-left lobe), then classify the skyrmion as Néel-like. This is circular: the data cannot simultaneously determine the Seebeck anisotropy and validate the fingerprint. No measurement on a skyrmion of independently confirmed Bloch type is presented, so the discriminator has never been tested against a positive control. Moreover, Fig. 4 explicitly shows a continuum of mixed Bloch–Néel responses parameterized by x; without independent input, the 2D voltage map does not uniquely determine the texture. The final discussion also notes that helicity cannot be determined from SThEM alone, which, depending on terminology, sits in tension with the title claim. Until a known Bloch host is scanned with the same pipeline, or S∥ and S⊥ are measured independently on this stack, the fingerprinting result remains a plausible model prediction rather than a validated experimental capability.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript reports a scanning thermoelectric microscopy (SThEM) measurement of the local thermoelectric voltage from a single skyrmion in a Pt/Co/Ir multilayer, together with a semi-analytical thermoelectric model. The model decomposes the signal into anomalous Nernst, planar Nernst, and anisotropic magneto-thermopower contributions (Eqs. 1-3), and uses analytic Bloch- and Néel-type spin textures as inputs. Simulated images for the two texture types are shown to differ when the in-plane Seebeck anisotropy S∥ - S⊥ is nonzero, and the measured SThEM image is compared qualitatively with the simulations. The paper concludes that SThEM can fingerprint Bloch and Néel skyrmions. The experimental support consists of a single skyrmion image, an inferred value S∥ - S⊥ ≈ 0.25 µV/K, and a visual match to a Néel-type simulation; no Bloch-type skyrmion was measured.","tokens_in":13435,"tokens_out":4063,"duration_ms":49898,"significance":"If the claimed capability is established, SThEM would be a valuable, lab-based addition to the suite of nanoscale spin-texture probes, particularly because the signal decomposition is physically clean: the texture-discriminating contribution is explicitly traced to the m_x m_y term in Eq. (3b), and the model makes a falsifiable prediction that Bloch and Néel responses become identical when S∥ = S⊥. The stated noise floor of ≈15 nV indicates useful sensitivity. However, the central claim currently rests on a single qualitative comparison and on a Seebeck-anisotropy value inferred from the same image used for classification. The distinction between a model prediction and a demonstrated experimental capability is not yet resolved, so the significance is conditional pending a proper positive control or independent parameter determination.","major_comments":[{"comment":"The classification of the measured skyrmion as Néel-like is circular. The text states that the Yin-Yang-like shape and the lower-left lobe suggest a Néel-like texture with S∥ - S⊥ ≈ 0.25 µV/K, but that value is inferred from the same experimental image that is then used to identify the texture. Since Eqs. (3b) and (3c) show that the only texture-discriminating contributions (PNE and AMTP) are proportional to S∥ - S⊥, and Fig. 2(b)(iii)/(d)(iii) shows that the Bloch and Néel simulations coincide when S∥ = S⊥, the experimental image cannot simultaneously determine the anisotropy and validate the discriminator. An independent measurement of S⊥ and S∥ on this stack, or a positive control on a known Bloch-skyrmion host, is required to break this circularity.","section":"Qualitative comparison paragraph (Fig. 1(d); Fig. 4)"},{"comment":"The paper has no positive control for the fingerprinting claim: no Bloch-type skyrmion was measured, and Fig. 4 explicitly shows a continuum of mixed Bloch-Néel responses parameterized by x. With only one skyrmion and a qualitative visual match, the 2D voltage map does not uniquely determine the texture without additional input. The final discussion also concedes that helicity cannot be determined from SThEM alone. The claim that SThEM can 'fingerprint skyrmion types, Bloch and Néel' should therefore be reframed as a model prediction with a consistency check, or supported by a measurement on a known Bloch host using the same pipeline.","section":"Fig. 4 and final discussion paragraph"},{"comment":"The model's predictive power depends on the analytic spin textures faithfully representing the measured skyrmion. The authors note that the measured skyrmion is not a perfect circle and that magnetostatic contributions in multilayers can distort the texture, yet no quantitative fit metric or uncertainty analysis is provided for the comparison between the simulated and measured voltage maps. Because the PNE/AMTP signatures in Eqs. (3b)-(3c) depend on the local m_x m_y distribution, a distorted texture could plausibly mimic a different wall type, weakening the conclusion that the observed lobe pattern uniquely identifies a Néel-like texture.","section":"Model inputs (analytic spin textures from refs. 28 and 40)"}],"minor_comments":[{"comment":"There are several typographical errors, including 'Dzyaloshinskii–Moryia' (should be Moriya), 'skymrion' in the concluding paragraph, 'optolithogrpahy', 'the the local', and 'such at those found'. A careful proofreading pass is recommended.","section":"Throughout"},{"comment":"The phrase 'Yin–Yangesque' is informal and not precisely defined; consider replacing it with a more quantitative description of the lobe pattern.","section":"Introduction, first paragraph"},{"comment":"The sentence 'S N it the anomalous Nernst Seebeck coefficient' contains a typo and should read 'S N is the anomalous Nernst Seebeck coefficient'.","section":"Equation (3a) area"},{"comment":"The caption states that line profiles are 'averaged' but does not specify how many profiles were averaged or over what region; adding this detail would improve reproducibility.","section":"Figure 1 caption"},{"comment":"The data availability statement ends with an ellipsis and does not provide a working repository link; it should be completed before publication.","section":"Data Availability statement"}],"recommendation":"major_revision","confidential_remarks":"The manuscript is within the journal's scope and the transport model is sound, but the experimental demonstration is not yet sufficient to support the fingerprinting claim as stated. The most effective revision would add a positive control on a known Bloch-skyrmion host or an independent measurement of S∥ and S⊥ on the same multilayer, and would temper the abstract/conclusion language accordingly. A more complete data availability statement would also be appropriate."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The paper gives you a clean decomposition of the scanned thermoelectric signal into ANE, PNE, and AMTP, and it correctly shows why the PNE/AMTP patterns differ between Bloch and Néel textures. That part is new and well explained. The experimental image of a single skyrmion in a Pt/Co/Ir stack, with its asymmetric lobe structure, is a solid data point and worth reporting. The problem is the fingerprinting claim. The stress-test is right: the classification is not independently validated. The same voltage map that is used to infer S∥−S⊥ ≈ 0.25 µV/K is then compared to the model to conclude the skyrmion is Néel-like. That is circular. There is no measurement on a known Bloch skyrmion, so the discriminator has never seen a positive control. The authors are transparent about much of this, and they even note that helicity cannot be determined from SThEM alone, which sits uncomfortably with the title. The missing data repository link is a smaller but real practical issue. What is solid: the transport equations are standard, the parametrization of the spin textures follows prior work, and the qualitative match with the data is plausible. The paper also correctly acknowledges that real skyrmions may deviate from ideal textures, so the model is a fingerprinting suggestion rather than a proven capability. In my view the central argument—that SThEM can distinguish Bloch from Néel—is not yet established. It is a plausible model prediction that deserves to be tested on a Bloch-host material or with independently measured Seebeck coefficients. A serious referee should engage, not desk-reject, but the authors need to either provide that control or tone down the title and conclusions. I would not cite the fingerprinting claim as fact, but I would cite the model if I needed the PNE/AMTP decomposition. Bring it to reading group as a good case study in circular inference and probe-based imaging.","headline":"Clean transport model and a suggestive single-skyrmion image, but the experimental fingerprint claim is circular—the same map sets S∥−S⊥ and then uses it to classify the texture.","tokens_in":595,"tokens_out":1337,"would_cite":false,"duration_ms":36173,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["72.20.Pa","75.70.-i","75.75.-c"],"model":"deepseek-v4-flash","headline":"A skyrmion's thermoelectric map reveals its Bloch or Néel character.","keywords":["scanning thermoelectric microscopy","skyrmion","Bloch skyrmion","Néel skyrmion","anomalous Nernst effect","planar Nernst effect","spin caloritronics","thermoelectric fingerprinting"],"falsifier":"Measure SThEM on a material with independently confirmed Bloch skyrmions, such as a B20 lamella or a two-dimensional ferromagnet, with the wall type verified by Lorentz TEM or MFM, and check whether the measured lobe pattern is inverted relative to a Néel-textured device with the same Seebeck coefficients. If the two look identical even when $S_\\perp / S_\\parallel \\neq 1$, the fingerprinting claim fails.","tokens_in":12914,"feed_emoji":"🔥","tokens_out":6612,"duration_ms":66596,"temperature":0.7,"pith_summary":"The paper tries to show that the nanoscale thermoelectric voltage produced when a hot scanning probe touches a magnetic skyrmion carries enough spatial information to tell which kind of skyrmion it is. It combines scanning thermoelectric microscopy of one skyrmion in a platinum/cobalt multilayer with a model that decomposes the signal into anomalous Nernst, planar Nernst, and anisotropic magneto-thermopower contributions. The model predicts that Bloch and Néel skyrmions give different spatial patterns whenever the in-plane Seebeck coefficients are unequal, and the measured pattern is consistent with a Néel-like texture. If true, this turns an ordinary lab-based atomic force microscope into a fast, non-synchrotron tool for characterising skyrmion spin textures and accelerating skyrmion device development.","feed_headline":"Hot probe fingerprints Bloch vs Néel skyrmions","feed_subtitle":"Nanoscale thermoelectric voltage from a single skyrmion encodes its spin texture, so a lab AFM can label the wall type.","key_machinery":"The central object is the Seebeck tensor $\\mathbf{S}$ that converts a local thermal gradient $\\nabla T$ into an electric field $\\mathbf{E} = \\mathbf{S}\\,\\nabla T$, built from three thermoelectric effects: the anomalous Nernst effect (transverse field from out-of-plane magnetisation), the planar Nernst effect, and the anisotropic magneto-thermopower, with coefficients $S_N$, $S_\\perp$, and $S_\\parallel$. The argument works by feeding analytic Bloch and Néel skyrmion spin textures into the voltage integral and comparing the resulting spatial maps. The ratio $S_\\perp / S_\\parallel$ is the control knob: at $S_\\perp / S_\\parallel = 1$ the two textures produce identical maps, while away from unity the planar Nernst and anisotropic magneto-thermopower terms create inverted lobe patterns that fingerprint the wall type.","core_discovery":"The authors claim that the spatially resolved thermoelectric voltage from a single skyrmion is a convolution of the skyrmion's internal spin texture with the localised thermal gradient from a heated probe, and that this voltage can be used to distinguish Bloch from Néel skyrmions. Through modelling, they show that the anomalous Nernst effect is identical for both textures, while the planar Nernst effect produces an antisymmetric multi-lobe pattern that is inverted between the two types, and the anisotropic magneto-thermopower responds differently because it depends only on the y-component of the in-plane magnetisation. The measured zero-field SThEM image of a single skyrmion shows a Yin–Yang-like response with an additional lower-left lobe, suggesting a Néel-like texture with $S_\\parallel - S_\\perp \\approx 0.25\\,\\mu\\text{V}\\,\\text{K}^{-1}$, though the authors note that the real skyrmion is not a perfect circle and may deviate from the ideal texture. They also show that the fingerprint disappears when $S_\\perp / S_\\parallel = 1$, that helicity cannot be determined from SThEM alone because the $m_x m_y$ product is identical for both types, and that combining SThEM with MFM would give both wall type and helicity.","pith_inferences":["Because the planar Nernst lobe pattern is antisymmetric and simply changes sign between Bloch and Néel walls, a reader could train an automated classifier on the model maps to label skyrmion type from raw SThEM images, which the paper does not do.","The same Seebeck-tensor framework should extend to other chiral textures such as antiskyrmions, merons, or hybrid Bloch-Néel walls, where the in-plane spin winding differs in predictable ways.","The authors' observation that vertical temperature gradients and the spin Seebeck effect were left out suggests insulating skyrmion hosts could give additional texture contrast, since those systems suppress charge currents but not magnon heat transport.","If the technique matures, it could serve as an inline metrology step in the skyrmion-device fabrication cycle, replacing destructive or slow magnetic imaging for routine checks."],"forward_implications":["A standard scanning probe microscope can fingerprint individual skyrmions as Bloch or Néel without needing synchrotron or neutron facilities.","The same measurement can estimate the relative size of the in-plane Seebeck coefficients from the skyrmion's cross-sectional profile.","Combining SThEM with MFM would give both skyrmion type and helicity, enabling fast material screening.","The modelled distinguishability sets a material requirement: candidate devices should show a significant $S_\\parallel - S_\\perp$ difference to make the two textures separable.","The technique's roughly 15 nV noise floor means the predicted signals are measurable in realistic multilayer stacks."],"supporting_citations":[{"why":"Establishes the SThEM technique, the device-edge response, the thermal point-spread function, and the noise floor this paper builds on.","marker":"[48]"},{"why":"Supplies the analytic skyrmion spin-texture form used as the model input.","marker":"[28]"},{"why":"Provides the analytic texture and the MFM route for independently determining skyrmion helicity.","marker":"[40]"},{"why":"Documents hybrid Bloch-Néel walls in multilayers, used to explain possible deviations from ideal textures.","marker":"[31]"},{"why":"Prior measurement of a thermoelectric signature from an individual skyrmion that this work extends.","marker":"[26]"},{"why":"Provides the custom finite-difference solver used to simulate the heated-probe thermal gradient.","marker":"[54]"},{"why":"Supplies the Seebeck-tensor decomposition separating anisotropic magnetothermopower and planar Nernst effect.","marker":"[55]"},{"why":"Reports measured spin Seebeck coefficients in CoFeB/non-magnetic-metal bilayers that justify the parameter range.","marker":"[64]"},{"why":"Calculates the Seebeck-coefficient anisotropy magnitude used to justify a non-zero $S_\\perp / S_\\parallel$ difference.","marker":"[66]"}],"fun_headline_variants":["Thermoelectric fingerprint tells Bloch from Néel","Hot probe reads skyrmion wall type","SThEM maps single skyrmion heat response","Planar Nernst effect labels skyrmion texture","Yin-Yang thermovoltage IDs skyrmion type"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The analytic Bloch and Néel spin textures used in the model are assumed to match the real skyrmion, which in the measurement is not a perfect circle and may be distorted by magnetostatic effects, so the modelled fingerprint might not line up with actual images.","fun_headline_variants_meta":{"raw":{"variants":["Thermoelectric fingerprint tells Bloch from Néel","Hot probe reads skyrmion wall type","SThEM maps single skyrmion heat response","Planar Nernst effect labels skyrmion texture","Yin-Yang thermovoltage IDs skyrmion type"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000278,"raw_usage":{"total_tokens":1710,"prompt_tokens":1060,"completion_tokens":650,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":676,"completion_tokens_details":{"reasoning_tokens":573}},"tokens_in":676,"tokens_out":650,"duration_ms":6833,"temperature":1.0,"reasoning_tokens":573,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-06T22:32:32.405465+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure SThEM on a material with independently confirmed Bloch skyrmions, such as a B20 lamella or a two-dimensional ferromagnet, with the wall type verified by Lorentz TEM or MFM, and check whether the measured lobe pattern is inverted relative to a Néel-textured device with the same Seebeck coefficients. If the two look identical even when $S_\\perp / S_\\parallel \\neq 1$, the fingerprinting claim fails.","supporting_citations":[{"cited_title":"Puttock , author C","cited_arxiv_id":null,"evidence_quote":"Establishes the SThEM technique, the device-edge response, the thermal point-spread function, and the noise floor this paper builds on."},{"cited_title":"Romming , author A","cited_arxiv_id":null,"evidence_quote":"Supplies the analytic skyrmion spin-texture form used as the model input."},{"cited_title":"Barton , author A","cited_arxiv_id":null,"evidence_quote":"Provides the analytic texture and the MFM route for independently determining skyrmion helicity."},{"cited_title":"Fern\\'andez Scarioni , author C","cited_arxiv_id":null,"evidence_quote":"Prior measurement of a thermoelectric signature from an individual skyrmion that this work extends."},{"cited_title":"Klapetek , author J","cited_arxiv_id":null,"evidence_quote":"Provides the custom finite-difference solver used to simulate the heated-probe thermal gradient."},{"cited_title":"Reimer , author D","cited_arxiv_id":null,"evidence_quote":"Supplies the Seebeck-tensor decomposition separating anisotropic magnetothermopower and planar Nernst effect."}],"review_version":1}