{"id":"34e83e85-394f-4221-939c-80e5aad3e407","arxiv_id":"2607.14011","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":2,"one_line_summary":"TbAuPb is a new antiferromagnetic half-Heusler semimetal (TN = 5 K) whose calculated band order flips from inverted to trivial when magnetism is switched on.","lead":"TbAuPb, a newly grown half-Heusler crystal, orders antiferromagnetically at 5 K and shows a field-driven magnetic transition near 5 T. Transport and density-functional calculations suggest it is a semimetal whose band order may switch from inverted to trivial under magnetic field.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Central topological claim is based on DFT for nonmagnetic and ferromagnetic states, while the measured ground state is AFM and the high-field state is non-collinear AFM; the paper itself concedes AFM calculations are inadequate without the magnetic structure.","rationale":"The reader's weakest_assumption identifies the same load-bearing concern that I find most significant: the band-structure calculations are performed for nonmagnetic and ferromagnetic configurations, while the experimentally realized ground state is antiferromagnetic and the high-field state is non-collinear AFM. The manuscript itself contains a clear limitation statement in Section IV admitting that, without the AFM magnetic structure, AFM calculations 'may prove questionable or completely inadequate.' This is not a manufactured objection; it is a direct admission that the central topological claim rests on an unverified substitution of magnetic states. The abstract's phrase 'field-induced ferromagnetic state' also appears inconsistent with the body text, which describes the high-field phase as a different AFM phase, possibly non-collinear. This discrepancy further weakens the link between the DFT result and the physical system. I agree with the CONDITIONAL verdict: the experimental characterization appears solid and the topological claim is explicitly framed as a prediction, but the key calculation has not yet been done for the actual magnetic phases. My concrete test—neutron diffraction followed by AFM band-structure calculations with a topological invariant—would directly settle whether the band inversion survives in the real material. If it does not, the abstract's headline claim would need to be substantially revised; if it does, the paper's conditional status could be upgraded. Thus no change to the reader's verdict is needed.","tokens_in":13015,"tokens_out":4485,"duration_ms":40607,"concrete_test":"Determine the magnetic structure of the low-field AFM phase and the high-field (B > 5 T) phase by neutron diffraction on TbAuPb single crystals. Using that magnetic unit cell, recompute the MBJGGA+U+SOC band structure and compute the Z2 invariant (or Chern number) for the AFM states. If the Γ6/Γ8 order is no longer inverted or the invariant is trivial, the abstract's central claim is unsupported; if it remains inverted and nontrivial, the claim survives.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The abstract states that TbAuPb is a band-inverted semimetal in the nonmagnetic state and becomes topologically trivial in the field-induced ferromagnetic state. But the experiments in Sec. III show the zero-field ground state is AFM (TN = 5 K) and the high-field phase above Bc ≈ 5 T is described as a 'different antiferromagnetic phase' with non-collinear moments, not a ferromagnet; magnetization does not saturate up to 7 T. The DFT calculations in Sec. IV model a hypothetical nonmagnetic state and a ferromagnetic state with M ∥ [001] (MBJGGA+U, Ueff = 7 eV), neither of which corresponds to the measured phases. The authors explicitly state: 'without knowledge of the magnetic structure of this material, the results of such calculations may prove questionable or completely inadequate' (Sec. IV). Thus the central claim would hold only if AFM exchange splitting preserves the nonmagnetic Γ6/Γ8 band inversion and if the high-field non-collinear AFM state is equivalent to the modeled FM state. Neither condition is tested; no topological invariant is computed. The 'transient state between topologically trivial and nontrivial' is inferred from orbital character, not from a Berry-phase or Z2 calculation.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper reports a combined experimental and computational study of the new half-Heusler compound TbAuPb. Single crystals are grown by self-flux, characterized by EDX and single-crystal XRD, and studied via magnetization, specific heat, resistivity, magnetoresistance, angular magnetoresistance, and Hall effect. The compound orders antiferromagnetically at TN = 5 K and shows a field-induced transition near Bc ≈ 5 T into a different, suspected non-collinear antiferromagnetic phase. Transport is semimetallic and hole-dominated, with multiband Hall response at high temperatures. DFT calculations (MBJGGA, MBJGGA+U) are used to argue that nonmagnetic TbAuPb is a band-inverted semimetal and that a hypothetical ferromagnetic state has a topologically trivial band order, placing the compound near a topological critical point. The abstract and summary present band inversion and the field-induced transition to a topologically trivial state as central findings.","tokens_in":13373,"tokens_out":3808,"duration_ms":39994,"significance":"If the topological interpretation were established, TbAuPb would be a welcome new member of the small family of magnetic half-Heuslers in which magnetism and band topology can be tuned by a magnetic field, complementing recent work on GdAuPb and RAuSn. The experimental part is carefully done: the structure solution, stoichiometry, thermodynamic transitions, and the systematic magnetotransport dataset are valuable and likely reproducible. The authors also deserve credit for explicitly stating the limitation of DFT without the experimental magnetic structure. However, the paper's headline claim is not supported by the calculations as presented: no topological invariant is computed, and the calculated nonmagnetic and ferromagnetic states do not correspond to the measured ground state or the measured high-field phase. The central claim therefore needs substantial revision or additional work before publication.","major_comments":[{"comment":"The central claim is that TbAuPb is band-inverted in the nonmagnetic state and becomes topologically trivial in the 'field-induced ferromagnetic state.' This does not match the experimental facts reported in §III.A and §III.B: the zero-field ground state is antiferromagnetic (TN = 5 K), and the high-field phase above Bc ≈ 5 T is described as 'a different antiferromagnetic phase' with non-collinear moments; magnetization does not saturate up to 7 T. The DFT in §IV models a hypothetical nonmagnetic state and a ferromagnetic state with M ∥ [001], and the authors themselves state that AFM calculations without the magnetic structure 'may prove questionable or completely inadequate.' Thus the computed band ordering is not demonstrated to apply to the real material. Either the claims about the actual material must be removed/reframed as hypothetical, or the AFM band structure must be computed o","section":"Abstract, §III.A, §IV"},{"comment":"The band-inversion/topological-triviality conclusion is inferred solely from the s/p orbital character of the Γ6/Γ7/Γ8 bands. No topological invariant — Z2 index, Wilson loop, or surface-state calculation — is presented. This is insufficient for half-Heuslers: as the paper itself notes (ref. 43), ARPES on RPtBi shows trivial metallic surface states even when bulk calculations suggest an inverted gap. The phrase 'transient state between topologically trivial and nontrivial band order' is also not defined quantitatively. A concrete topological invariant calculation for the nonmagnetic phase and for the candidate magnetic phases is needed before the words 'topologically trivial/nontrivial' can be used.","section":"§IV, Fig. 5"},{"comment":"The summary states that the Hall resistivity 'indicates the presence of anomalous Hall effect in the AFM state,' but the text in §III.B says the anomalous Hall resistivity 'cannot be reliably separated from the experimental Hall data because of multiband contributions, and also the magnetization does not saturate.' The observed slope change near Bc is explicitly attributed to either a modification of anomalous Hall or Fermi-surface reconstruction. Since the paper highlights anomalous Hall as one of the phenomena to be explored, the claim in the Summary should be softened to a possibility, or a quantitative subtraction/analysis must be provided.","section":"§III.B, Summary"},{"comment":"The two-band Hall analysis is used to support the 'hole-dominated multiband' conclusion, but the fitted parameters in Table I show a very large and non-monotonic variation of n1 (1.5×10^19 at 100 K, 3.8×10^18 at 200 K, 6.5×10^19 at 300 K) with no error bars or stability discussion. In addition, Eq. (1) contains an undefined factor 1/m, where m is described as 'the number of Fermi pocket'; this looks like a typo and should be clarified. The qualitative conclusion of hole-dominated transport is plausible, but the quantitative claim of multiband analysis needs more care.","section":"Eq. (1), Table I"}],"minor_comments":[{"comment":"The abstract first says the high-field phase is 'a different antiferromagnetic phase' and then refers to the 'field-induced ferromagnetic state' in the last sentence. This internal inconsistency should be fixed.","section":"Abstract"},{"comment":"Please define all symbols in Eq. (1) and remove or explain the factor 1/m. As written, the formula does not match the standard two-band Hall conductivity expression.","section":"Eq. (1)"},{"comment":"'The experimental lattice parameter of the face-centered cubic primitive cell' is confusing: the conventional cubic cell has a = 6.745 Å. Please clarify the cell used in the DFT calculations.","section":"§II.A"},{"comment":"Several references are incomplete or malformed: ref. 10 lacks volume/page details ('Adv. Funct. Mater., e22474 (2025)'), ref. 26 similarly lacks volume/page, and ref. 38 has a garbled author string ('G. Y. Y.-C. L. X. Xi').","section":"References"},{"comment":"The caption and text say the FM band structure was calculated for magnetization directions [001], [111], and [011], but only [001] is discussed in detail in the main text. Briefly state whether the same U and convergence parameters were used for all three directions.","section":"Fig. 6"}],"recommendation":"major_revision","confidential_remarks":"The experimental study is solid and likely of interest to the half-Heusler/magnetic topological semimetal community. The main problem is that the paper overclaims the topological conclusion: the headline statement is not supported by the calculations, which concern hypothetical states rather than the measured AFM phases, and no topological invariant is computed. I believe this can be fixed within the scope of a revision by substantially qualifying the language, reframing the DFT results as a scenario/hypothesis, and possibly adding a topological invariant calculation for the nonmagnetic phase. If the authors prefer to keep the strong claims, they would need neutron diffraction or equivalent determination of the magnetic structure and a full AFM band-structure calculation."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague, the useful news here is the material itself. TbAuPb is new, the single-crystal growth looks clean, and the experimental core - structure, TN = 5 K AFM order, field-induced transition near 5 T, heat capacity, resistivity, Hall data - is coherent and internally consistent. The two-band Hall fits are only used above 100 K where they are defensible, and the paper does not oversell the extracted carrier parameters. The authors also say outright that without the magnetic structure, AFM band calculations would be questionable or inadequate. That is the right kind of honesty, and it covers the main weakness of the theoretical section. Where the paper wobbles is in the abstract. It says TbAuPb becomes topologically trivial in the 'field-induced ferromagnetic state,' but the experiments do not show a ferromagnetic state - magnetization does not saturate up to 7 T, and the authors describe the high-field phase as a different, likely non-collinear AFM phase. So the headline claim is being made for a state that was not observed. The DFT models a hypothetical nonmagnetic state and an FM state with moments along [001], neither of which corresponds to the measured ground state or the actual high-field phase. That gap matters. The 'band inversion' conclusion is also based on orbital character and band ordering, not on a computed Z2 invariant or Berry curvature, and the paper itself calls for further Berry curvature calculations. The Ueff = 7 eV choice is asserted, not tested. That said, the experimental contribution does not depend on the DFT story. If you read the paper as a characterization study with a speculative topological gloss, it holds up well. The main revision points for peer review are: fix the abstract so it does not describe the high-field phase as ferromagnetic, explicitly label the topological statements as model-dependent, and ideally either compute a topological invariant for the modeled states or soften the claim. The pressure-dependent band structure shown in the supplement is a nice addition, though brief. This is the kind of paper I would send to a serious referee rather than desk reject. It is the first experimental report on a new half-Heusler compound, the data quality looks good, and the limitations are mostly stated in the text if not in the abstract. A careful referee could push the authors to make the presentation match the evidence, and the result would be a useful paper for the rare-earth half-Heusler community. I would bring it to a reading group focused on magnetic topological materials, and I would cite it if I worked on RAuPb or related series.","headline":"Solid first characterization of a new half-Heusler, but the topological headline is a conditional DFT statement about states that were not measured; the authors mostly admit this, and the abstract overstates it.","tokens_in":702,"tokens_out":1728,"would_cite":true,"duration_ms":32730,"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":"The half-Heusler TbAuPb is calculated to be a band-inverted semimetal whose band topology flips when ferromagnetic order sets in.","keywords":["half-Heusler","TbAuPb","topological semimetal","band inversion","antiferromagnetism","magnetoresistance","angular magnetoresistance","Hall effect"],"falsifier":"Determine the magnetic structure of the antiferromagnetic ground state by neutron diffraction and compute the band structure with that order and spin-orbit coupling; if the Γ6/Γ8 inversion disappears in the antiferromagnetic state, TbAuPb is not a band-inverted semimetal in its real ground state. An independent check is angle-resolved photoemission: a nontrivial band inversion would yield an odd number of surface-state crossings at the Fermi level, which ARPES can observe.","tokens_in":12935,"feed_emoji":"🧲","tokens_out":8886,"duration_ms":81129,"temperature":0.7,"pith_summary":"TbAuPb is a newly grown half-Heusler compound, and this paper sets out to establish that it is a band-inverted semimetal sitting near a topological critical point. First-principles calculations show that if the material were nonmagnetic, the Γ6 and Γ8 states at the zone centre would be inverted—the configuration that makes half-Heuslers topologically nontrivial—while in the field-induced ferromagnetic state the band order becomes trivial. The experiments characterise the actual material: it orders antiferromagnetically at 5 K, undergoes a spin-reorientation near 5 T, and shows semimetallic, hole-dominated, multiband transport with a butterfly-shaped angular magnetoresistance above the transition. A sympathetic reading is that TbAuPb is a promising platform for studying how magnetism toggles band topology, with the caveat that the topology claim rests on calculations of magnetic states that bracket, but do not include, the real antiferromagnetic ground state.","feed_headline":"A magnetic field may flip this semimetal's band order","feed_subtitle":"New half-Heusler TbAuPb is band-inverted when nonmagnetic and topologically trivial when ferromagnetic.","key_machinery":"The engine of the claim is band inversion between the Γ6 and Γ8 states at the zone centre, the established ordering criterion for topology in half-Heusler compounds. Strong spin-orbit coupling, amplified by the heavy Tb, Au and Pb atoms, pushes the Γ8 manifold above the Γ6 state in the nonmagnetic calculation; exchange splitting in the ferromagnetic calculation reverses this order. The paper also uses the band-inversion strength parameter t = (Z_T + Z_X)V, whose value for TbAuPb (~49 nm^3) is close to those of known band-inverted half-Heuslers, to argue that the compound is near the threshold where external tuning can switch the topology.","core_discovery":"The central claim is that TbAuPb, a heavy half-Heusler with all three constituents from the lower part of the periodic table, has inverted Γ6/Γ8 band order in its nonmagnetic state, making it a topological semimetal candidate; in the ferromagnetic state the calculation restores a trivial band order, though with a transient character near the Γ7/Γ6 states. The paper backs this with the experimental finding of a semimetallic, hole-dominated transport and an antiferromagnetic ground state whose spin reorientation at about 5 T is strongly coupled to the transport. The calculations also show the band inversion survives moderate pressure but can collapse at higher pressure, and the authors place t","pith_inferences":["The real zero-field ground state is antiferromagnetic, not nonmagnetic; unless the AFM exchange splitting preserves the Γ6/Γ8 inversion, the 'band-inverted semimetal' description may hold only for a hypothetical paramagnetic phase, leaving the material's true zero-field topology open.","The field-induced high-field state is described as non-collinear and its magnetization does not saturate, so the collinear ferromagnetic calculation may not represent the state the field actually produces; a calculation with the true non-collinear order could alter the predicted triviality.","The supplementary pressure calculation suggests that a few-percent lattice compression changes the Γ6 band position; strain engineering in thin films might thereby be a practical way to switch the topology, a route not explored in the paper.","The butterfly-shaped angular magnetoresistance resembles what has been attributed to magnetic band reconstruction in other half-Heuslers; testing whether it tracks the calculated band-order change as a function of field direction would separate topology-driven from purely magnetic effects."],"forward_implications":["If the calculations are right, TbAuPb is a new member of the rare-earth half-Heusler family in which magnetism can drive a topological-to-trivial transition in a single material.","Its position close to a topological critical point means moderate hydrostatic pressure or chemical substitution could push it across the transition in zero field, offering a knob for topology.","The observed anomalies in the Hall effect and the butterfly-shaped angular magnetoresistance near the spin-reorientation field could serve as transport fingerprints of the topology switch, testable by future experiments.","Because the crystals are clean single crystals, ARPES and quantum oscillation measurements can directly check the predicted Fermi-surface pockets and band inversion."],"fun_headline_variants":["TbAuPb flips from band-inverted to trivial with field","Magnetic field toggles TbAuPb's topological band order","Half-Heusler TbAuPb: field turns semimetal trivial","Spin reorientation rewires TbAuPb's charge transport"],"cache_read_input_tokens":2304,"weakest_assumption_plain":"The band-topology conclusion is drawn from density-functional calculations of the nonmagnetic and ferromagnetic states, but the material's actual zero-field ground state is antiferromagnetic with an unknown spin arrangement; if the antiferromagnetic exchange splitting changes the Γ6/Γ8 ordering, the central claim about band inversion collapses.","fun_headline_variants_meta":{"raw":{"variants":["TbAuPb flips from band-inverted to trivial with field","Magnetic field toggles TbAuPb's topological band order","Half-Heusler TbAuPb: field turns semimetal trivial","Spin reorientation rewires TbAuPb's charge transport"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000208,"raw_usage":{"total_tokens":1209,"prompt_tokens":679,"completion_tokens":530,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":423,"completion_tokens_details":{"reasoning_tokens":452}},"tokens_in":423,"tokens_out":530,"duration_ms":5423,"temperature":1.0,"reasoning_tokens":452,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-02T03:00:38.824120+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Determine the magnetic structure of the antiferromagnetic ground state by neutron diffraction and compute the band structure with that order and spin-orbit coupling; if the Γ6/Γ8 inversion disappears in the antiferromagnetic state, TbAuPb is not a band-inverted semimetal in its real ground state. An independent check is angle-resolved photoemission: a nontrivial band inversion would yield an odd number of surface-state crossings at the Fermi level, which ARPES can observe.","supporting_citations":[],"review_version":1}