{"id":"96da6308-2ae1-4f4f-a39e-fb333b66f632","arxiv_id":"2605.25953","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":6.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":0,"one_line_summary":"Epitaxial alpha-MnTe films on Si(111) exhibit anomalous Hall effect from uncompensated Berry curvature due to altermagnetic symmetry breaking.","lead":"This paper reports epitaxial growth of alpha-MnTe thin films on Si(111) substrates and the observation of a hysteretic anomalous Hall effect in this altermagnetic material despite zero net magnetization. The work could enable integration of Berry-phase spintronic effects into existing silicon semiconductor platforms.","discovery_kind":"new_application","skeptic_critique":{"model":"grok-4.3","headline":"Distinguishing intrinsic altermagnetic Berry curvature from possible extrinsic interface/defect contributions remains the least-secured step in the central claim.","rationale":"The reader’s weakest_assumption directly isolates the same attribution gap that the abstract itself flags as needing structural and transport data to resolve. Because the provided information (abstract plus the statement that full text exists) contains no additional quantitative controls or scaling arguments that would close this gap, the load-bearing concern remains exactly as identified and does not warrant shifting the UNVERDICTED verdict.","tokens_in":1724,"tokens_out":390,"duration_ms":20492,"concrete_test":"Re-measure the Hall conductivity on the same MnTe/Si(111) films after intentional interface modification (e.g., insertion of a 2–3 nm amorphous Si or oxide buffer) while confirming that the altermagnetic order parameter (via neutron diffraction or magnetometry) remains unchanged; if the hysteretic AHE amplitude drops by >50 % while the longitudinal resistivity and structural quality stay comparable, the extrinsic-interface contribution cannot be ruled out.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The strongest claim asserts that the observed hysteretic Hall response constitutes clear evidence of finite Berry curvature generated by symmetry breaking in the thin-film geometry, despite zero net magnetization. This interpretation rests on the assumption that structural/spectroscopic confirmation of phase-pure epitaxial NiAs-type growth plus first-principles calculations of uncompensated Berry curvature are sufficient to exclude extrinsic sources (interface states at Si(111), minor uncompensated moments, or measurement artifacts). The abstract notes correlated hysteresis in transverse and longitudinal channels with temperature evolution, yet provides no quantitative scaling, control-sample data, or explicit exclusion of those alternatives; the calculations are described only as “consistent with” the altermagnetic state, leaving open whether the measured signal magnitude and temperature dependence actually match the predicted intrinsic contribution.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.3","summary":"The manuscript reports molecular-beam-epitaxy growth of phase-pure α-MnTe thin films on Si(111), structural confirmation of hexagonal NiAs-type symmetry, and the observation of a hysteretic anomalous Hall effect (AHE) in the absence of net magnetization. The AHE is attributed to uncompensated Berry curvature arising from altermagnetic symmetry breaking in the thin-film geometry, with first-principles calculations cited as consistent with the measured transport response and temperature evolution.","tokens_in":1881,"tokens_out":415,"duration_ms":17030,"significance":"If the central interpretation holds, the work establishes a silicon-compatible altermagnetic platform that integrates Berry-phase-driven spintronic functionality with mainstream semiconductor technology, addressing a key materials bottleneck for scalable altermagnetic devices.","major_comments":[{"comment":"Abstract and magnetotransport section: the claim that the observed hysteretic Hall response constitutes 'clear evidence' of intrinsic uncompensated Berry curvature is not secured by quantitative comparison of the measured Hall resistivity magnitude or its temperature dependence against the first-principles Berry-curvature integral; without such scaling or error analysis, extrinsic interface or defect contributions cannot be excluded at the level required for the central claim.","section":"Abstract / magnetotransport measurements"},{"comment":"Structural and spectroscopic characterization: while phase purity and epitaxial registry are reported, no quantitative bounds are given on possible minority phases, interface reconstruction, or strain-induced moments that could produce an extrinsic AHE; these bounds are load-bearing for the assertion that the response originates solely from altermagnetic symmetry breaking.","section":"High resolution structural and spectroscopic characterization"}],"minor_comments":[{"comment":"The abstract refers to 'correlated hysteresis in both transverse and longitudinal channels' without specifying the longitudinal resistivity component or its scaling with the Hall signal; a brief clarification would improve readability.","section":"Abstract"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for their careful reading and constructive feedback. We address each major comment point by point below.","responses":[{"response":"We agree that the manuscript would benefit from a more explicit quantitative comparison between the measured Hall resistivity and the Berry-curvature integral from first-principles calculations. The existing calculations demonstrate that altermagnetic symmetry breaking produces uncompensated Berry curvature whose sign and temperature evolution are consistent with the data, but we did not perform a direct scaling or error analysis. In the revised manuscript we will add this comparison, including an estimate of the expected AHE magnitude from the calculated Berry curvature and a discussion of possible extrinsic contributions. We will also revise the abstract wording from 'clear evidence' to language that reflects the consistency with the intrinsic mechanism while acknowledging the need for further exclusion of extrinsic effects.","revision_made":"partial","referee_comment":"[Abstract / magnetotransport measurements] Abstract and magnetotransport section: the claim that the observed hysteretic Hall response constitutes 'clear evidence' of intrinsic uncompensated Berry curvature is not secured by quantitative comparison of the measured Hall resistivity magnitude or its temperature dependence against the first-principles Berry-curvature integral; without such scaling or error analysis, extrinsic interface or defect contributions cannot be excluded at the level required for the central claim."},{"response":"We acknowledge that explicit quantitative bounds on minority phases and potential extrinsic sources are necessary to support the central claim. The reported XRD and TEM data indicate phase-pure epitaxial growth, yet upper limits on minority-phase fractions were not quantified. In the revision we will extract and report quantitative bounds from the XRD peak intensities (e.g., minority phases <1 %) and will add discussion of the absence of detectable interface reconstruction or strain-induced moments, based on the measured lattice parameters, rocking-curve widths, and the lack of net magnetization in SQUID magnetometry. These additions will directly address the load-bearing requirement identified by the referee.","revision_made":"yes","referee_comment":"[High resolution structural and spectroscopic characterization] Structural and spectroscopic characterization: while phase purity and epitaxial registry are reported, no quantitative bounds are given on possible minority phases, interface reconstruction, or strain-induced moments that could produce an extrinsic AHE; these bounds are load-bearing for the assertion that the response originates solely from altermagnetic symmetry breaking."}],"tokens_in":1327,"tokens_out":503,"duration_ms":29074,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"The paper grows phase-pure alpha-MnTe films on Si(111) by MBE and reports hysteretic Hall response with no net magnetization. Structural and spectroscopic data confirm the NiAs-type structure, and the temperature dependence of the transverse and longitudinal hysteresis is shown together. First-principles results are presented as consistent with uncompensated Berry curvature from the altermagnetic band structure.\n\nThat combination is new: prior MnTe work did not include direct silicon integration with this transport signature. The growth and basic characterization appear reproducible from the description, and the absence of net moment is stated clearly.\n\nThe remaining issue is whether the Hall signal is generated by the altermagnetic symmetry breaking or by interface states, minor defects, or measurement effects. The abstract and stress-test note both flag that the calculations are only described as consistent rather than quantitatively matched to the measured magnitude and its temperature scaling. No control samples that deliberately break the altermagnetic order are mentioned, so the exclusion of extrinsic channels stays incomplete.\n\nThe work is aimed at groups trying to bring altermagnets onto CMOS-compatible lines. Readers focused on materials integration and transport will find the growth details and raw hysteresis data useful even if they want tighter controls.\n\nIt should go to peer review. The platform result is specific enough to be checked, and the central claim can be strengthened or corrected with additional data.","headline":"Epitaxial alpha-MnTe on Si(111) with observed AHE is the concrete step forward, but the case for intrinsic Berry curvature over extrinsic sources is not yet tight.","tokens_in":2449,"tokens_out":362,"would_cite":false,"duration_ms":20760,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.3","headline":"Alpha-MnTe films grown directly on silicon show a hysteretic Hall response from altermagnetic Berry curvature despite zero net magnetization.","keywords":["altermagnetism","anomalous Hall effect","alpha-MnTe","silicon integration","epitaxial thin films","Berry curvature","molecular beam epitaxy","spintronics"],"falsifier":"Observation of identical hysteretic Hall response in polycrystalline or randomly oriented MnTe films of the same thickness would indicate that the effect does not require the epitaxial altermagnetic symmetry.","tokens_in":2619,"feed_emoji":"🧲","tokens_out":644,"duration_ms":14718,"temperature":0.7,"pith_summary":"The paper establishes that epitaxial alpha-MnTe thin films can be grown on Si(111) by molecular beam epitaxy while retaining the altermagnetic state. In this geometry the spin-split bands produce an uncompensated Berry curvature that yields a clear anomalous Hall effect, even though the material carries no net magnetic moment. Structural and transport data confirm phase purity and epitaxial registry, while first-principles calculations tie the observed Hall signal to the altermagnetic symmetry. If correct, the result supplies a concrete route to embed Berry-phase spintronics inside conventional silicon device flows.","feed_headline":"Altermagnetic MnTe on silicon produces anomalous Hall effect","feed_subtitle":"Epitaxial films exhibit hysteretic Hall response from uncompensated Berry curvature despite zero net magnetization.","key_machinery":"Uncompensated Berry curvature arising from the altermagnetic spin-split bands in the thin-film geometry.","core_discovery":"Epitaxial alpha-MnTe thin films on Si(111) exhibit a pronounced hysteretic anomalous Hall effect generated by finite, uncompensated Berry curvature that arises from the breaking of compensation symmetry in the thin-film geometry; first-principles calculations confirm that the altermagnetic spin-split band structure supplies this curvature, establishing MnTe/Si(111) as a silicon-compatible platform for Berry-phase-driven functionalities.","pith_inferences":["Similar symmetry-breaking routes may allow other altermagnetic candidates to be integrated on silicon once suitable epitaxial conditions are identified.","Device architectures that rely on Hall readout rather than magnetization reversal could be tested directly on these films.","Temperature-dependent scaling of the Hall conductivity offers a way to separate intrinsic Berry-phase contributions from extrinsic scattering terms."],"forward_implications":["MnTe can be integrated directly into silicon-based device flows without buffer layers.","The anomalous Hall response persists across a range of temperatures with correlated longitudinal and transverse hysteresis.","First-principles band calculations reproduce the measured Hall conductivity from the altermagnetic band structure.","The thin-film geometry supplies the symmetry breaking needed to generate net Berry curvature in an otherwise compensated altermagnet."],"fun_headline_variants":["Altermagnetic MnTe on Si(111) exhibits anomalous Hall effect","Epitaxial alpha-MnTe on silicon shows hysteretic Hall effect","Finite Berry curvature in altermagnetic MnTe/Si films","Silicon-compatible MnTe films display anomalous Hall effect"],"cache_read_input_tokens":2112,"weakest_assumption_plain":"The measured hysteretic Hall signal is produced by intrinsic Berry curvature of the altermagnetic state rather than by defects, interfaces, or measurement artifacts.","fun_headline_variants_meta":{"raw":{"variants":["Altermagnetic MnTe on Si(111) exhibits anomalous Hall effect","Epitaxial alpha-MnTe on silicon shows hysteretic Hall effect","Finite Berry curvature in altermagnetic MnTe/Si films","Silicon-compatible MnTe films display anomalous Hall effect"]},"model":"grok-4.3","cost_usd":0.007794,"raw_usage":{"total_tokens":3548,"prompt_tokens":646,"num_sources_used":0,"completion_tokens":71,"cost_in_usd_ticks":77937000,"prompt_tokens_details":{"text_tokens":646,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":2831,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":646,"tokens_out":71,"duration_ms":23106,"temperature":1.0,"reasoning_tokens":2831,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-06-29T21:30:46.699929+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"Observation of identical hysteretic Hall response in polycrystalline or randomly oriented MnTe films of the same thickness would indicate that the effect does not require the epitaxial altermagnetic symmetry.","supporting_citations":[],"review_version":1}