{"id":"a7ecd990-a62f-47ac-ba6d-09d2eb456429","arxiv_id":"2411.16184","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"First-principles calculations identify Cr3Te4 as a ferromagnetic Weyl semimetal with long Fermi arcs, large anomalous Hall conductivity, and a parallel Hall conductivity, with measured Curie temperature 327 K.","lead":"This paper predicts that the magnetic material Cr3Te4 is a Weyl semimetal with special transport signatures, and reports that it is ferromagnetic up to about 327 K. A careful reader might care because a room-temperature magnetic Weyl semimetal could be useful for spintronics and topological electronics.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The assumed collinear FM order along a contradicts the canted magnetic structure reported in the paper's own Sec. III A and Ref. [51]; if the true ground state is non-collinear, the symmetry-enforced Weyl points and Hall conductivities are not established.","rationale":"The reader's weakest assumption is exactly the concern we find most load-bearing: the calculation's magnetic configuration is not the experimentally established one. This concern is not a peripheral parameter choice; it controls the symmetry analysis (Sec. III B and III D) that predicts the Weyl point topology and the anomalous and parallel Hall conductivities. If the canted state is the true ground state, the reported tau My and tau C2y symmetries are broken, so the partner-Weyl-point argument and the allowed conductivity tensor components both fail. The paper itself supplies the experimental evidence (Fig. 2, Ref [51]) but does not address it in the calculations, leaving the central claim conditional. A non-collinear calculation is a direct test. Other issues such as missing convergence tests and sparse details on Weyl point positions also matter, but they are secondary. Thus the verdict should remain conditional, i.e., unchanged from the reader's assessment.","tokens_in":13348,"tokens_out":4432,"duration_ms":57101,"concrete_test":"Perform a non-collinear DFT calculation starting from the experimentally reported canted spin state (FM component along a, AFM component along (a+b)) in the C2/m cell, allowing full moment relaxation; then recompute Weyl points, Fermi arcs, and sigma_yz and sigma_xy in the converged state. If the Weyl points and large Hall conductivities survive, the collinear approximation is validated; if they change or vanish, the paper's central predictions are contingent on an unsupported magnetic ground state.","verdict_should_be":"UNCHANGED","load_bearing_attack":"All topological and transport claims rest on a collinear ferromagnetic configuration with Cr moments along the a direction (Sec. III A). Yet the same section presents M(T) data showing a second transition near 70 K and cites neutron diffraction [51] finding a canted spin arrangement with antiferromagnetic components along (a+b). For this canted state the magnetic space group is generically reduced: the anti-unitary symmetries tau My and tau C2y, used in Sec. III D to enforce sigma_zx = 0 and to allow non-zero sigma_yz and sigma_xy, may no longer be symmetries of the Hamiltonian. If those symmetries are lost, the Weyl point partner mapping in Sec. III B no longer holds, and the predicted multiple Weyl points, long Fermi arcs, and parallel anomalous Hall conductivity in a given energy window could disappear or be strongly modified. Since the experimental characterization is part of the paper itself, this is an internal consistency risk, not merely a disagreement with external consensus. The authors do not model the canted state or show that its electronic structure is equivalent for the topological quantities.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper predicts, from PBE-GGA density-functional calculations with spin-orbit coupling and Wannier interpolation, that monoclinic Cr3Te4 in a collinear ferromagnetic state with Cr moments along the a direction is a magnetic Weyl semimetal. The authors report multiple Weyl points near the Fermi level, long Fermi arcs on the (1-bar-1-bar-0) surface (0.83 inverse Angstroms), a conventional anomalous Hall conductivity sigma_yz of about 260 inverse Ohm-centimeter, a parallel anomalous Hall conductivity sigma_xy of about 100 inverse Ohm-centimeter at the Fermi level, and anomalous Nernst conductivities alpha_yz of about 0.39 and alpha_xy of about 0.72 Ampere per meter-Kelvin at 300 K. They support these calculations with experimental XRD and magnetization data, including a Curie temperature of 327 K and a second magnetic transition near 70 K. The symmetry analysis uses the anti-unitary operations tau My and tau C2y to conclude sigma_zx = 0 and to allow nonzero sigma_xy and sigma_yz.","tokens_in":13563,"tokens_out":6289,"duration_ms":59933,"significance":"If the predictions are correct, Cr3Te4 would be a room-temperature magnetic Weyl semimetal with large Berry-curvature charge and thermoelectric responses, including a sizable parallel anomalous Hall effect. Strengths of the paper are that the transport coefficients are computed from the ab initio band structure without fitting any parameter to Hall or Nernst data, and that the symmetry reasoning is transparent and falsifiable by future ARPES and transport experiments. However, the central topological and transport claims rely on a collinear ferromagnetic ground state that appears to be inconsistent with the canted magnetic structure described in the authors' own experimental section, so the significance of the results for the actual material is not yet established.","major_comments":[{"comment":"The symmetry analysis and Weyl-partner mapping presume a collinear ferromagnetic state with all Cr moments along x, but the authors' own Sec. III A states that neutron diffraction [51] finds a canted spin configuration with antiferromagnetic components along (a+b) and that M(T) shows a second transition near 70 K. In a canted or non-collinear ground state, the magnetic space group generically lacks the anti-unitary operations tau My and tau C2y that are used in Sec. III D to enforce sigma_zx=0 and to allow nonzero sigma_xy and sigma_yz. The predicted Weyl points, Fermi arcs, and both Hall conductivities therefore may not survive in the experimentally relevant magnetic phase. The manuscript must either repeat the electronic-structure and transport calculations for the canted magnetic configuration, or provide an explicit justification for why the collinear approximation captures the topological and transport properties.","section":"Sec. III A and Sec. III D"},{"comment":"The quantitative values sigma_yz of about 260, sigma_xy of about 100, alpha_yz of about 0.39, and alpha_xy of about 0.72 are obtained from Brillouin-zone integrals of the Berry curvature over Wannier-interpolated bands, yet the paper reports no convergence tests with respect to k-mesh density or smearing width, and no error estimates. Because the crossings are described as lying slightly away from high-symmetry paths and the Berry curvature is sharply peaked near such crossings, the reported numerical values are not robustly established. The authors should provide a convergence study (for example, increasing the k-mesh for the AHC integration and varying the smearing) and, ideally, a check of the sensitivity to the PBE exchange-correlation choice.","section":"Sec. III D and Sec. III E"},{"comment":"The claim of 'multiple Weyl points' is not documented with a quantitative inventory. No table or list reports the k-space coordinates, energies, chiralities, or pairing of the Weyl points, and the text notes that the actual crossings occur slightly away from the high-symmetry paths shown in Fig. 1(c). In addition, the 0.83 inverse Angstrom Fermi-arc length in Table I is quoted at the Fermi energy, while the text states that arcs are prominent in a 0.0-0.15 eV window and that part of the arcs merge into bulk states; the definition of the measured arc length and the specific Weyl pair connected by the longest arc need to be stated explicitly.","section":"Sec. III B and Sec. III C"}],"minor_comments":[{"comment":"The caption lists panels as (a) Omega_x, (b) Omega_y, and (c) Omega_z, but the text refers to 'Fig. 4(c)' for Omega_y and 'Fig. 4(b) and (d)' for Omega_x and Omega_z; the panel labels and references should be reconciled.","section":"Fig. 4"},{"comment":"The entry 'Cd' for a conventional ferromagnet appears to be a typo for Co, since the text and Ref. [57] refer to Fe, Co, FePt, FePd, and Ni.","section":"Table II"},{"comment":"The notation switches between sigma_zx and sigma_xz; for consistency one symbol should be used throughout.","section":"Sec. III D"},{"comment":"The symbol epsilon is used both for the Levi-Civita symbol and for the band energy, and the sign convention for the Hall tensor is not fixed; please disambiguate the notation.","section":"Eq. (1)"},{"comment":"The sentence beginning 'In our system ferromagnetically aligned magnetic moments are predominantly present on the Cr atoms are aligned along the x direction' is grammatically incomplete and should be rewritten.","section":"Sec. III A"},{"comment":"Table III lists 'Theoretical' and 'Experimental' cell parameters that differ, although the Methods section states that the experimental structure was used; please clarify whether relaxation was performed and, if so, report the relaxation settings.","section":"Appendix A"}],"recommendation":"major_revision","confidential_remarks":"The main risk is the internal inconsistency between the collinear ferromagnetic model used in all calculations and the canted magnetic structure cited in the authors' own Sec. III A. This is a load-bearing issue, not a minor caveat, because the symmetry operations used to enforce the Hall tensor structure and Weyl-point pairing are not guaranteed to survive in the canted state. I would ask the authors to either model the canted phase or substantially weaken the claims about the experimentally relevant ground state. I do not see circularity in the transport calculation, since no parameter is fitted to the Hall or Nernst data."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Fair bit to digest here. The paper predicts multiple Weyl points near the Fermi level in Cr3Te4, with a Fermi arc length of 0.83 inverse angstroms, a conventional anomalous Hall conductivity of 260 per ohm-cm, a parallel anomalous Hall conductivity of 100 per ohm-cm, and sizable anomalous Nernst conductivities at 300 K. If those numbers hold up, Cr3Te4 would be a useful room-temperature magnetic Weyl semimetal. That is the new piece: no one had proposed Weyl points or the parallel Hall effect in this compound before.\n\nThe paper does several things well. The symmetry analysis is refreshingly concrete: they show that tau My forces sigma_zx to vanish and tau C2y allows the xy and yz components, and the computed Berry curvature components match that picture. The surface-state calculations give long, distinct Fermi arcs, and the comparison with other magnetic Weyl materials is helpful. The experimental XRD and magnetization data confirm the monoclinic structure and a Curie temperature near 327 K, which supports the room-temperature relevance.\n\nThe soft spot is the magnetic order. The paper assumes a collinear ferromagnetic alignment of Cr moments along the a-direction. Yet in their own Sec. III A they cite neutron diffraction [51] showing a canted spin configuration with antiferromagnetic components along (a+b). If the true ground state is canted, the antiunitary symmetries tau My and tau C2y are generically lost, and the Weyl points and the Hall conductivity components are no longer symmetry-protected. The authors do not model the canted state or explain why it would not affect the topological properties. That is an internal inconsistency, not just an external debate. It is possible that the canted phase only appears below 70 K and the high-temperature ferromagnetic phase is collinear, but the paper does not make that case.\n\nA second, softer issue is the absence of convergence tests or error estimates for the Berry curvature integrals. For a prediction of this kind, a short statement on k-mesh density and smearing would be expected. The PBE functional without Hubbard U is also a known risk for Cr d-electron systems; a comparison with GGA+U or a brief justification would strengthen the results. The measured saturation moment, 2.68 uB, sits below the calculated moments, which hints that the assumed magnetic configuration is not exact.\n\nOverall, this is a solid first-principles prediction with a real internal-consistency problem. The reader's conditional verdict is about right. The paper deserves a serious referee, but the referee should ask for the canted magnetic structure to be addressed explicitly, plus convergence and functional checks. I would not reject it outright; I would send it back for major revision.","headline":"Prediction of a room-temperature magnetic Weyl semimetal in Cr3Te4 with large Fermi arcs and parallel AHE, but the assumed collinear magnetic order clashes with the canted structure the paper itself cites.","tokens_in":14095,"tokens_out":3277,"would_cite":false,"duration_ms":31252,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"Calculations predict Cr3Te4 is a room-temperature magnetic Weyl semimetal.","keywords":["Cr3Te4","Weyl semimetal","anomalous Hall effect","parallel anomalous Hall effect","anomalous Nernst effect","Berry curvature","ferromagnetism","first-principles calculations"],"falsifier":"A low-temperature neutron or resonant X-ray scattering experiment that resolves the magnetic structure would settle it: if the chromium moments form the canted configuration described in Ref. [51] rather than collinear order along $a$, the combined symmetries $\\tau M_y$ and $\\tau C_{2y}$ are broken, and the predicted Weyl points and in-plane Hall conductivities should disappear. Alternatively, ARPES on the $(\\bar{1}\\bar{1}0)$ surface that fails to find Fermi arcs of roughly $0.83\\ \\mathrm{\\AA}^{-1}$ would contradict the surface-state prediction.","tokens_in":13147,"feed_emoji":"🧲","tokens_out":8806,"duration_ms":70003,"temperature":0.7,"pith_summary":"The paper aims to establish that the layered, monoclinic ferromagnet Cr$_3$Te$_4$ is an intrinsic magnetic Weyl semimetal, with multiple Weyl points—gapless band crossings that act as sources and sinks of Berry curvature—close to the Fermi level and Fermi arcs long enough to be seen in photoemission. It argues that the Berry curvature produced by these Weyl points generates both a conventional anomalous Hall conductivity of about $260\\ \\Omega^{-1}\\mathrm{cm}^{-1}$ and an unconventional 'parallel' anomalous Hall conductivity of about $100\\ \\Omega^{-1}\\mathrm{cm}^{-1}$ along an in-plane direction. It further derives anomalous Nernst conductivities of about $0.39$ and $0.72\\ \\mathrm{A\\,m^{-1}K^{-1}}$ at 300 K from the same Berry curvature via the Mott relation. Complementary magnetization measurements put the Curie temperature near 327 K, so a correct prediction would make Cr$_3$Te$_4$ a candidate for room-temperature topological and spintronic applications.","feed_headline":"Cr3Te4 predicted as room-temperature magnetic Weyl semimetal","feed_subtitle":"Calculations find long Fermi arcs plus large Hall and Nernst responses near 300 K.","key_machinery":"The load-bearing object is the magnetic space group of monoclinic Cr$_3$Te$_4$ in its assumed ferromagnetic state. The centrosymmetric crystal (space group C2/m) becomes magnetic when chromium moments order along $a$, breaking time reversal but preserving the combined symmetries $\\tau M_y$ and $\\tau C_{2y}$. These combined symmetries dictate which Berry curvature components survive, constrain the Weyl-point partners, enforce $\\sigma_{zx}=0$, and permit the coexistence of the conventional Hall conductivity $\\sigma_{yz}$ and the parallel Hall conductivity $\\sigma_{xy}$; the parallel component is the low-symmetry effect called the parallel anomalous Hall effect. The numerical machinery is first-principles electronic structure with tight-binding interpolation, followed by Berry curvature integration; the Nernst conductivities are obtained from the Hall conductivities through the Mott relation.","core_discovery":"On its own terms, the paper claims that ferromagnetic Cr$_3$Te$_4$, with chromium moments aligned along the $a$ axis, hosts multiple pairs of Weyl points near the Fermi level. Under the combined symmetry operations $\\tau M_y$ and $\\tau C_{2y}$ (time reversal followed by a mirror or a twofold rotation), the Berry curvature components $\\Omega_x$ and $\\Omega_z$ are allowed to be nonzero while $\\Omega_y$ vanishes, which forces $\\sigma_{zx}=0$ and leaves two independent transverse Hall conductivities: the conventional $\\sigma_{yz}\\sim260\\ \\Omega^{-1}\\mathrm{cm}^{-1}$ at the Fermi level and the unconventional parallel $\\sigma_{xy}\\sim100\\ \\Omega^{-1}\\mathrm{cm}^{-1}$. The same Berry curvature yields anomalous Nernst conductivities $\\alpha_{yz}\\sim0.39$ and $\\alpha_{xy}\\sim0.72\\ \\mathrm{A\\,m^{-1}K^{-1}}$ at 300 K. Surface calculations on the $(\\bar{1}\\bar{1}0)$ face show Fermi arcs extending about $0.83\\ \\mathrm{\\AA}^{-1}$, roughly three-quarters of the surface reciprocal vector, which the authors expect to be detectable by ARPES and STM.","pith_inferences":["The symmetry argument implies a strong sensitivity to magnetic structure: if the low-temperature canted phase suggested by neutron diffraction is the true ground state, the combined symmetries $\\tau M_y$ and $\\tau C_{2y}$ may be lost and the predicted Weyl points and parallel Hall effect may not survive.","A natural extension is to compute the band topology using the experimentally reported canted magnetic configuration; this would directly show whether the Weyl phase is a property of the actual magnetic ground state or only of the idealized collinear order.","The same symmetry analysis could be applied to other chromium telluride intercalates (such as CrTe, Cr$_2$Te$_3$, and Cr$_5$Te$_8$) to search for parallel Hall effects and Weyl points as a family-wide feature.","Because the parallel Hall conductivity is allowed only when mirror and twofold rotational symmetries are broken by the moment direction, rotating the magnetization with an external field should switch the pattern of allowed Hall components; this is a testable prediction the paper does not spell out."],"forward_implications":["If the prediction holds, Cr$_3$Te$_4$ becomes a bulk, room-temperature magnetic Weyl semimetal, a category with very few confirmed members.","The long Fermi arcs should be observable in surface-sensitive ARPES and STM experiments, providing a direct test of the Weyl topology.","Electron or hole doping could tune the Hall responses substantially, for example raising $\\sigma_{xy}$ to about $320\\ \\Omega^{-1}\\mathrm{cm}^{-1}$ at a Fermi-level shift of 0.14 eV and $\\alpha_{xy}$ to about $1.19\\ \\mathrm{A\\,m^{-1}K^{-1}}$ at a shift of 65 meV.","The coexistence of conventional and parallel anomalous Hall effects, plus sizable anomalous Nernst responses, suggests possible Berry-curvature-based thermoelectric and spintronic devices operating near room temperature."],"supporting_citations":[{"why":"Establishes that Weyl points produce non-closed Fermi arcs, the surface signature used to identify the topological phase.","marker":"[8]"},{"why":"Provides the kagome-lattice magnetic Weyl semimetal Co3Sn2S2, whose Fermi-arc length is the benchmark for Cr3Te4's longer arcs.","marker":"[25]"},{"why":"Supplies the experimental crystal structure of Cr3Te4 on which all calculations are based.","marker":"[45]"},{"why":"Reports the canted magnetic structure with antiferromagnetic components, the experimental evidence that bears on the assumed collinear order.","marker":"[51]"},{"why":"Gives the symmetry transformation rule for Hall conductivity components under rotations, used to derive which components vanish.","marker":"[54]"},{"why":"Defines the unconventional anomalous Hall effect with magnetization parallel to the electric field, the phenomenon identified as the parallel AHE here.","marker":"[59]"},{"why":"Provides the Berry-phase transport relation used to compute the anomalous Nernst conductivities from the Hall conductivities.","marker":"[61]"}],"fun_headline_variants":["Cr3Te4: room-temp Weyl semimetal with dual Hall effects","Parallel Hall effect in Cr3Te4, a ferromagnetic Weyl semimetal","Cr3Te4 Weyl semimetal: large anomalous Nernst effect","Dual Hall and Nernst signals in room-temp Weyl semimetal Cr3Te4"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The prediction rests on the assumption that the magnetic ground state is collinear ferromagnetic order with all chromium moments along the $a$ axis, while the paper's own magnetization data and cited neutron diffraction suggest a canted configuration with antiferromagnetic components along $a+b$.","fun_headline_variants_meta":{"raw":{"variants":["Cr3Te4: room-temp Weyl semimetal with dual Hall effects","Parallel Hall effect in Cr3Te4, a ferromagnetic Weyl semimetal","Cr3Te4 Weyl semimetal: large anomalous Nernst effect","Dual Hall and Nernst signals in room-temp Weyl semimetal Cr3Te4"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000813,"raw_usage":{"total_tokens":3623,"prompt_tokens":1060,"completion_tokens":2563,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":676,"completion_tokens_details":{"reasoning_tokens":2469}},"tokens_in":676,"tokens_out":2563,"duration_ms":17036,"temperature":1.0,"reasoning_tokens":2469,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-12T13:27:03.436924+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A low-temperature neutron or resonant X-ray scattering experiment that resolves the magnetic structure would settle it: if the chromium moments form the canted configuration described in Ref. [51] rather than collinear order along $a$, the combined symmetries $\\tau M_y$ and $\\tau C_{2y}$ are broken, and the predicted Weyl points and in-plane Hall conductivities should disappear. Alternatively, ARPES on the $(\\bar{1}\\bar{1}0)$ surface that fails to find Fermi arcs of roughly $0.83\\ \\mathrm{\\AA}^{-1}$ would contradict the surface-state prediction.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Provides the kagome-lattice magnetic Weyl semimetal Co3Sn2S2, whose Fermi-arc length is the benchmark for Cr3Te4's longer arcs."},{"cited_title":"Babot, M","cited_arxiv_id":null,"evidence_quote":"Supplies the experimental crystal structure of Cr3Te4 on which all calculations are based."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Reports the canted magnetic structure with antiferromagnetic components, the experimental evidence that bears on the assumed collinear order."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Gives the symmetry transformation rule for Hall conductivity components under rotations, used to derive which components vanish."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Defines the unconventional anomalous Hall effect with magnetization parallel to the electric field, the phenomenon identified as the parallel AHE here."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Provides the Berry-phase transport relation used to compute the anomalous Nernst conductivities from the Hall conductivities."}],"review_version":1}