{"id":"94ccadf5-693d-4671-ad0c-fbfa4b2b6567","arxiv_id":"2604.23297","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":6.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":0,"one_line_summary":"Noise spectroscopy of charge fluctuations in itinerant altermagnets yields symmetry-protected signatures absent in antiferromagnets, enabling experimental identification and access to d-wave or g-wave orbital character via bulk, strain, and domain-wall geometries.","lead":"This paper theoretically explores noise magnetometry as a tool to identify and characterize altermagnetic order by analyzing magnon and charge fluctuation contributions in insulating and itinerant systems. It identifies symmetry-allowed noise signatures unique to altermagnets that could distinguish them from antiferromagnets and reveal the orbital character of the order.","discovery_kind":"new_application","skeptic_critique":{"model":"grok-4.3","headline":"No significant objection identified","rationale":"The reader's weakest assumption correctly flags the gap between idealized symmetry signatures and experimental dominance, but this is an external applicability issue rather than an internal flaw in the symmetry argument itself. Because the manuscript is a theoretical proposal without parameter fitting or material-specific numerics, the load-bearing condition for the claim is precisely the one the reader already isolated; no additional technical vulnerability was located.","tokens_in":1767,"tokens_out":253,"duration_ms":45723,"concrete_test":"Re-derive the allowed noise correlators for the itinerant case (around a domain wall) using only the altermagnetic point-group representations without invoking the specific dipole-tensor lattice correction mentioned in the abstract; verify that the angular dependence distinguishing d-wave vs. g-wave character survives unchanged.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim rests on symmetry-allowed noise terms (magnon and charge) that are forbidden in antiferromagnets but permitted in altermagnets, both in bulk and under strain/domain walls. The argument is internally consistent within the idealized models used; no internal contradiction or hidden assumption that would invalidate the symmetry classification is apparent from the symmetry-based construction.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.3","summary":"The manuscript proposes noise spectroscopy (via magnon and charge fluctuations) as a tool for unambiguous experimental identification of altermagnetic order. It uses symmetry arguments to show that certain noise contributions are allowed in altermagnets but forbidden in antiferromagnets, both in the homogeneous bulk and under strain or near domain walls. For itinerant altermagnets the charge-noise signatures are highlighted as particularly distinctive, while the angular dependence of noise around domain walls is argued to encode the orbital character (d-wave vs. g-wave) of the order parameter. Lattice corrections arising from the dipole tensor are also examined.","tokens_in":1822,"tokens_out":460,"duration_ms":50020,"significance":"If the symmetry classification holds, the work supplies concrete, falsifiable predictions that could help distinguish altermagnets from conventional antiferromagnets in a range of candidate materials. The explicit treatment of both insulating and itinerant regimes, together with the inclusion of strain and domain-wall geometries, broadens the proposal's applicability. The symmetry-based construction yields signatures that are, in the idealized models, independent of microscopic details, which is a clear strength for experimental design.","major_comments":[],"minor_comments":[{"comment":"§3 (itinerant-electron noise): the statement that charge fluctuations provide the 'most striking' signatures would be strengthened by a brief quantitative comparison (e.g., relative magnitude or frequency window) to the magnon contribution already derived in §2.","section":"§3"},{"comment":"Fig. 4 (domain-wall noise): the angular dependence is central to the orbital-character claim, yet the figure caption does not specify the precise definition of the angle or the integration limits used for the noise power; this should be clarified for reproducibility.","section":"Fig. 4"},{"comment":"The discussion of lattice dipole-tensor corrections (near the end of §4) is useful but appears only after the main results; moving a short summary of these corrections to the introduction would help readers assess their impact on the symmetry-allowed terms from the outset.","section":"§4"}],"recommendation":"minor_revision","confidential_remarks":null},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for the positive assessment of our manuscript, the recognition of its significance for distinguishing altermagnets from antiferromagnets via noise spectroscopy, and the recommendation for minor revision. No specific major comments were listed in the report, so we have no point-by-point rebuttals to provide. We will incorporate any minor editorial or technical suggestions in the revised version.","responses":[],"tokens_in":1313,"tokens_out":94,"duration_ms":26983,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"The one thing to know is that this paper argues noise spectroscopy can distinguish altermagnets from antiferromagnets by picking up charge noise terms that symmetry allows only in the former, particularly in itinerant systems and near domain walls. The new element is the detailed look at itinerant charge fluctuations. Most altermagnet proposals so far target insulating cases or magnon modes, but here they show how mobile electrons produce noise signatures tied to the altermagnetic symmetry. The angular dependence around domain walls is presented as a way to access the orbital character, like d-wave versus g-wave. They also cover the homogeneous bulk and strained cases. The work does well on the symmetry side. The classification of allowed noise channels follows logically from the different magnetic point groups, and the inclusion of lattice dipole tensor effects shows attention to realistic details. The claims avoid self-reference and stay within standard models. Soft spots appear in the experimental translation. The predictions assume the symmetry-allowed terms dominate over disorder, phonons, and instrumental noise, but no estimates of relative magnitudes are given. This makes it difficult to assess how clean the signal would be in candidate materials. The models for itinerant electrons and magnons are standard but may miss material-specific effects. This paper targets experimentalists seeking practical tools for altermagnet identification in metals. Readers focused on spin noise or domain wall dynamics in unconventional magnets would find the concrete channels useful. The theoretical foundation is sound enough that it deserves a serious referee to check the derivations and any numerical results. I recommend sending it out for peer review.","headline":"Noise spectroscopy could distinguish altermagnets from antiferromagnets via charge fluctuations allowed only by altermagnetic symmetry, especially near domain walls.","tokens_in":2313,"tokens_out":383,"would_cite":false,"duration_ms":86165,"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":"Altermagnets produce unique noise signatures in charge fluctuations that symmetry forbids in antiferromagnets.","keywords":["altermagnetism","noise spectroscopy","magnons","itinerant electrons","domain walls","symmetry signatures","charge fluctuations"],"falsifier":"A noise measurement around domain walls in a candidate altermagnet that shows no angular-dependent charge fluctuations permitted only by altermagnetic symmetry would falsify the claim.","tokens_in":2659,"feed_emoji":"📊","tokens_out":617,"duration_ms":28092,"temperature":0.7,"pith_summary":"The paper explores noise magnetometry to identify altermagnetic order by comparing noise from magnons and itinerant electrons. It shows that symmetry permits certain noise terms only in altermagnets, creating clear distinctions from antiferromagnets in both bulk samples and under strain or near domain walls. These signatures are especially prominent in charge fluctuations of itinerant altermagnets. The angular pattern of noise around domain walls further encodes the orbital character of the order, such as d-wave versus g-wave.","feed_headline":"Noise signatures tag altermagnets uniquely","feed_subtitle":"Symmetry permits charge noise terms in altermagnets that antiferromagnets forbid, even in bulk or near defects.","key_machinery":"Symmetry-allowed contributions to noise in charge fluctuations of itinerant altermagnets, which are forbidden in antiferromagnets.","core_discovery":"While altermagnetism and antiferromagnetism lead to different noise spectra for magnons, the most striking and symmetry-sensitive signatures appear in the charge fluctuations of itinerant altermagnets. Both for the homogeneous bulk case and in the presence of strain and/or around domain walls, noise contributions exist that are only permitted by symmetry in the altermagnet and thus provide a unique signature. The angular dependence of noise around domain walls also offers access to the orbital character of the altermagnet.","pith_inferences":["Noise spectroscopy could serve as a screening tool for identifying altermagnetism in new candidate materials without relying on transport or diffraction.","The approach might extend to detecting other symmetry-broken magnetic phases by similar symmetry filtering of fluctuations.","If confirmed, it would support device concepts that use domain walls or strained regions in altermagnets for noise-based sensing."],"forward_implications":["Altermagnets and antiferromagnets exhibit distinct magnon noise spectra.","Charge fluctuations in itinerant altermagnets carry symmetry-specific noise terms absent in antiferromagnets.","Strain and domain walls enable additional unique noise contributions allowed only by altermagnetic symmetry.","The angular dependence of noise around domain walls encodes the orbital character of the altermagnetic order parameter."],"fun_headline_variants":["Symmetry permits charge noise in altermagnets","Domain wall noise maps altermagnet orbital character","Itinerant altermagnets show distinct charge fluctuations","Noise spectra separate altermagnets from antiferromagnets"],"cache_read_input_tokens":64,"weakest_assumption_plain":"The symmetry-based noise terms dominate over real-world effects such as disorder, phonons, and experimental resolution limits.","fun_headline_variants_meta":{"raw":{"variants":["Symmetry permits charge noise in altermagnets","Domain wall noise maps altermagnet orbital character","Itinerant altermagnets show distinct charge fluctuations","Noise spectra separate altermagnets from antiferromagnets"]},"model":"grok-4.3","cost_usd":0.009478,"raw_usage":{"total_tokens":4177,"prompt_tokens":718,"num_sources_used":0,"completion_tokens":62,"cost_in_usd_ticks":94778000,"prompt_tokens_details":{"text_tokens":718,"audio_tokens":0,"image_tokens":0,"cached_tokens":64},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":3397,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":718,"tokens_out":62,"duration_ms":40963,"temperature":1.0,"reasoning_tokens":3397,"cache_read_input_tokens":64,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-05-08T07:31:14.265563+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"A noise measurement around domain walls in a candidate altermagnet that shows no angular-dependent charge fluctuations permitted only by altermagnetic symmetry would falsify the claim.","supporting_citations":[],"review_version":1}