{"id":"89676b11-e5c8-408a-9dd5-116e5081ced7","arxiv_id":"2411.13309","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":2,"one_line_summary":"Spin-orbit torque with three-dimensional spin polarization can anisotropically tune both high- and low-frequency spin-wave bands in canted antiferromagnetic YFeO3 from tens of gigahertz to sub-terahertz.","lead":"The authors calculate how a spin current from a platinum layer can shift the frequencies of spin waves in the antiferromagnet YFeO3, depending on the direction of the current's spin polarization. If correct, this offers an electrically tunable source of terahertz radiation from magnetic materials.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The quoted SOT field H_DT is inconsistent with the stated conversion formula: Methods parameters (M_s=200 A/m, t=4 nm) give ~82 T for J_c=2.5e12 A/m^2, not the 0.52 T used throughout, so all quantitative frequency-shift predictions depend on an unresolved factor of ~158.","rationale":"The reader identified the same weakest point, and I agree. I checked the arithmetic: with hbar/2e = 3.29e-16, theta_H*J_c = 2e11, and M_s*t = 8e-7, the formula gives H_DT ~ 82 T. The paper's 0.52 T cannot be recovered from the printed M_s unless a hidden factor of ~158 is applied. This is the most load-bearing issue because all frequency tunings, including the central claim of efficient sub-THz tunability, depend on H_DT (in the small-H limit, quadratically for both the p//l coupling and the p perpendicular l reorientation). The anisotropic mechanism itself is physically reasonable: p parallel to l couples the two bands, while p perpendicular to l reorients the equilibrium and reduces anisotropy. The analytical structure is coherent, and the numerical section even states that adjusted parameters were used, so the analytical/numerical agreement in Figs. 2-4 cannot be checked without code. Given the internal inconsistency, the correct action is to keep the CONDITIONAL verdict and require a corrected conversion, an explicit definition of M_s, and reproducible simulation parameters. I therefore recommend no change to the reader's verdict.","tokens_in":12378,"tokens_out":13641,"duration_ms":145882,"concrete_test":"Recompute H_DT from the Methods formula for J_c=2.5e12 A/m^2, theta_H=0.08, t=4 nm using three values of M_s: 200 A/m (as printed), 3.2e4 A/m (implied by H_DT=0.52 T), and the literature YFeO3 weak moment (~5.6e3 A/m). Then re-solve the linearized Eqs. (7)-(12) at q=0 for each H_DT and compare the resulting Delta f with Figs. 2b, 2d, and 2f. If any corrected H_DT changes Delta f by more than 10%, the quantitative claims and the efficiency comparison to H_ext in the 'Current density dependence' section require revision, and the manuscript should state which M_s is intended.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The quantitative central claim is carried by a single conversion: H_DT = J_c (hbar/2e) theta_H/(M_s t) (Methods). Inserting the paper's parameters (M_s=200 A/m, t=4 nm, theta_H=0.08, J_c=2.5e12 A/m^2) gives H_DT ~ 82 T, not the 0.52 T quoted in the text and Fig. 2b. The mismatch is a factor of ~158; conversely, 0.52 T implies M_s ~ 3.2e4 A/m, which is close to the weak-ferromagnetic moment of YFeO3 and far from 200 A/m. This is an internal inconsistency in the parameter set, not a matter of convention. Because the quoted frequency shifts (e.g., Delta f = +85.2 GHz / -58.4 GHz at q=0 for p//x), the self-oscillation thresholds (J_c,self ~ 2.73e12 A/m^2 for H_DT,self = 0.56 T), and the asserted superiority over external-field tuning all depend on H_DT, the quantitative predictions are not self-consistent. At the stated M_s, the chosen currents would also be far above the self-oscillation threshold, contradicting the 'just before self-oscillation' regime in Fig. 2. The qualitative mechanism (coupling for p//l, reorientation for p perpendicular l) is plausible, but every headline number must be re-derived from a corrected conversion.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript presents an analytical and numerical study of spin-orbit torque (SOT) control of spin waves in the canted biaxial antiferromagnet YFeO3. From a free-energy model with exchange, biaxial anisotropies, and Dzyaloshinskii-Moriya interaction, the authors derive coupled equations for the Néel order and identify polarization-dependent effects: damping-like SOT with polarization parallel to the Néel vector couples the high- and low-frequency spin-wave bands, while perpendicular polarizations reorient the equilibrium orientation and reduce the frequencies. The authors report frequency shifts up to roughly 150 GHz for currents on the order of 10^12 A/m^2, discuss self-oscillation thresholds, and compare the tuning efficiency with that of an external magnetic field. Numerical LLG simulations of the total magnetization dynamics are used to support the analytics.","tokens_in":12737,"tokens_out":10354,"duration_ms":99145,"significance":"If the quantitative results can be made self-consistent, the work would offer a route to electrically tunable sub-terahertz magnons in canted antiferromagnets and an appealing physical picture of SOT as a coupling spring between the two spin-wave branches. The analytical derivation is largely self-contained from a stated free energy and standard LLG equations, and the qualitative polarization dependence is a useful extension of earlier AFM SOT studies. However, the numerical simulations rely on undisclosed adjusted parameters, and the central current-to-effective-field conversion contains an internal inconsistency, so the quantitative predictions are not currently reliable.","major_comments":[{"comment":"The effective damping-like SOT field is defined as H_DT = J_c (hbar/2e) theta_H/(M_s t) (text following Eq. (4)). With the stated parameters M_s = 200 A/m, t = 4 nm, theta_H = 0.08, and J_c = 2.5e12 A/m^2, this formula gives approximately 82 T, not the 0.52 T quoted in the text and used in the figures. The discrepancy is a factor of about 158. This error propagates to all quantitative claims: the Delta-f values in the section on current density dependence, the self-oscillation threshold J_c,self ~ 2.73e12 A/m^2 with H_DT,self = 0.56 T, and the comparison with external-field tuning. At the stated M_s, J_c = 2.5e12 A/m^2 would be roughly 150 times the self-oscillation threshold, contradicting the 'just before self-oscillation' regime stated in the text. The authors must correct the parameter set or the quoted H_DT values so that the conversion is self-consistent, and then re-derive all quantitative results.","section":"Methods, H_DT definition after Eq. (4)"},{"comment":"The numerical simulations are described as using 'adjusted magnetic parameters' and 'energetic adjustment to reduce the simulation time' and as requiring 'alternating signs of DM interaction' in the mesh (Section 'Total magnetization dynamics'; Methods; Supplementary Note 1). The adjusted values are not disclosed. Because the numerical symbols in Figs. 2 and 4 are presented as validation of the analytics, using undisclosed parameter adjustments makes the agreement non-reproducible and potentially a fit rather than a prediction. The authors should report the exact parameters, the form of the energy adjustment, and the physical justification for the alternating DM signs, or demonstrate that the conclusions are insensitive to these choices.","section":"Total magnetization dynamics and Methods"},{"comment":"The Fig. 4 caption labels panel b as Jc = 2.5e12 A/m^2 with p//y and panel c as Jc = 1.2e12 A/m^2 with p//x, whereas the main text uses Jc = 2.5e12 A/m^2 for p//x and Jc = 1.2e12 A/m^2 for p//y. In the same way, the paragraph comparing SOT with external-field tuning states 'at p//y, Jc = 2.5e12 A m^-2 is converted to magnetic field H_DT = 0.52 T, leading to Delta f = 85.2 GHz (k = 0 LF mode) and 58.4 GHz (q = 0 HF mode)', but those values correspond to the p//x case from the 'Current density dependence' section. These inconsistencies make it impossible to determine which polarization and current density underlie the claimed numerical spectra and the comparative claim of higher efficiency than external-field tuning.","section":"Fig. 4 captions and comparison paragraph"}],"minor_comments":[{"comment":"Current densities are sometimes written without the 10^12 factor, e.g., 'Jc of 2.5, 1.2, and 3.5 A m-2' and '1.2 3.5 A m-2' should read 10^12 A/m^2.","section":"Current density dependence section"},{"comment":"The typeset equations contain obvious corruption, including undefined symbols such as B in Eqs. (5)-(6) and missing exponents in several places. A clean, compilable version of the equations is needed so that the derivation can be checked.","section":"Equations (5)-(12)"},{"comment":"In the p//y subsection, the text says 'for Jc = 1.2e12 A m-2 or H_DT,self = 0.25 T'; the subscript 'self' should be removed because this is not the self-oscillation threshold.","section":"p//y case, Eq. (9)-(10) discussion"},{"comment":"The phrase 'the effective penetration depth t of spin current into YFeO3 of 4 nm' should be reworded as 'film thickness' unless a genuinely different length is intended.","section":"Methods, spin-current penetration"},{"comment":"The statement in the main text that 'we employed a linearized dispersion relation incorporating mesh and adjusted magnetic parameters in the numerical calculations' is referred to Supplementary Notes 1 and 2, but the supplementary material is not provided to the reader; the relevant values and definitions should be given in the main text or the supplement should be included.","section":"Numerical simulation description"}],"recommendation":"major_revision","confidential_remarks":"The paper would clearly benefit from a careful parameter audit before resubmission. The H_DT inconsistency and the swapped figure captions suggest that the manuscript has not been through a rigorous internal consistency check. If the intended M_s is about 3.2e4 A/m, many of the headline numbers may survive; if the physically appropriate sublattice magnetization of YFeO3 is used, the predicted tuning would be much weaker, which would reduce the significance of the work. The undisclosed numerical adjustments are an additional reproducibility concern that the editors may want to flag."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The core idea is worth your time: a canted biaxial antiferromagnet with DMI, driven by damping-like SOT with arbitrary polarization, shows two distinct control regimes—p parallel to the Neel vector couples the HF and LF bands via an effective spring, while p perpendicular reorients the equilibrium and lowers frequencies. That mapping, including both resonant and propagating modes, is not in the earlier SOT papers on alpha-Fe2O3, so it is a real increment. The derivation is self-contained from a stated free energy and LLG equations, with parameters from prior literature, so the mechanism itself is plausible and not circular.\n\nThe problem is quantitative. The Methods give H_DT = (hbar/2e) theta_H J_c/(M_s t). With their own numbers—M_s = 200 A/m, t = 4 nm, theta_H = 0.08, J_c = 2.5e12 A/m^2—this yields about 82 T, not the 0.52 T used throughout. That is a factor of 158. Every headline number depends on this conversion: the frequency shifts (e.g., +85.2 GHz/-58.4 GHz), the self-oscillation threshold (2.73e12 A/m^2 or 0.56 T), and the claimed superiority over external-field tuning. At the stated M_s, the quoted currents would sit far above self-oscillation, contradicting the 'just before self-oscillation' framing in Fig. 2. The paper also uses 'adjusted magnetic parameters' in the numerics without disclosing them, and the comparison section mixes up p//y and p//x for the same J_c. These are not cosmetic slips; they undercut the quantitative claims until fixed.\n\nFor a qualitative read, the physics is interesting and the polarization anisotropy is a useful conceptual advance. But as a quantitative proposal for tunable THz sources, the numbers are currently unreliable. A serious referee should ask for a corrected conversion and disclosed simulation parameters. The topic is relevant to AFM spintronics and the mechanism likely survives the fix, so it deserves peer review rather than a desk reject—but only with major revision.","headline":"Plausible mechanism and genuinely new polarization-dependent spin-wave map, but a factor-158 error in the SOT field conversion guts every quantitative prediction.","tokens_in":13244,"tokens_out":2358,"would_cite":false,"duration_ms":24931,"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":"Damping-like spin-orbit torque from a platinum layer can anisotropically shift both spin-wave bands of a canted biaxial antiferromagnet, coupling or reorienting them depending on spin polarization, yielding electrically tunable terahertz…","keywords":["antiferromagnetic spintronics","spin-orbit torque","spin waves","terahertz magnonics","canted antiferromagnet","YFeO3","spin wave dispersion","biaxial anisotropy"],"falsifier":"Measure the low-frequency standing-wave mode at $q=0.0167$ nm$^{-1}$ in a Pt/YFeO3 Hall bar under a DC current of $1.2\\times10^{12}$ A/m$^2$ with the polarization along $y$. The paper predicts a shift of $-38.6$ GHz; observing no comparable shift would show the tuning mechanism is much weaker than claimed.","tokens_in":12219,"feed_emoji":"🧲","tokens_out":9214,"duration_ms":90475,"temperature":0.7,"pith_summary":"Antiferromagnets have two spin-wave bands, a low-frequency and a high-frequency one, and this paper argues that a DC spin current from an adjacent heavy-metal layer can tune both before the system starts oscillating on its own. For a canted biaxial antiferromagnet such as YFeO3, the direction of the spin polarization decides the mechanism: polarization parallel to the Néel vector couples the two bands like a spring, while perpendicular polarization reorients the equilibrium and lowers both frequencies. Using the material parameters of YFeO3, the paper predicts shifts of tens of gigahertz to more than a hundred gigahertz, pushing the operating range from hundreds of gigahertz toward the sub-terahertz. Because the same dynamics also drive magnetization precession that emits terahertz radiation, the result points toward an electrically tunable, broadband terahertz source for wireless and ultrafast applications.","feed_headline":"Spin currents tune terahertz spin waves in a canted antiferromagnet","feed_subtitle":"Three spin polarizations shift both spin-wave bands by up to 34 percent before self-oscillation.","key_machinery":"The central object is the effective damping-like spin-orbit torque field $H_{\\mathrm{DT}}$ acting on the Néel vector $\\mathbf{l}$ of a biaxial canted antiferromagnet. In the linearized equations of motion this field generates a coupling constant $\\Omega=2\\gamma\\omega_E H_{\\mathrm{DT}}$ when the spin polarization is parallel to $\\mathbf{l}$, and it renormalizes the anisotropy terms when the polarization is perpendicular. The paper's picture is that of two pendulums, the low- and high-frequency modes, connected by a spring whose stiffness is proportional to the applied charge current. The same current-dependent resonant frequency enters the dispersion $\\omega^2=\\omega_0^2+c_c^2 k^2$, so both propagating and standing spin waves inherit the electrical tuning.","core_discovery":"The central discovery is that damping-like spin-orbit torque provides a polarization-dependent handle on the spin-wave spectrum of a canted biaxial antiferromagnet. Writing the Néel order in spherical angles, the torque introduces terms that either connect the two eigenmodes when the polarization lies along the Néel vector, or tilt the equilibrium orientation and soften the anisotropy barriers when it is perpendicular. For YFeO3, the low-frequency band sits at 300 GHz and the high-frequency at 525 GHz at zero current; at current densities just below self-oscillation the paper reports shifts such as +85.2 GHz and -58.4 GHz for polarization along x, -106 GHz and -25.8 GHz for polarization along y, and -158.1 GHz and -157.3 GHz for polarization along z at $q=0$. The same shifts appear, reduced in size, at finite wavevector and in standing-wave modes, and numerical simulations of the Landau-Lifshitz-Gilbert equation reproduce the analytical dispersions.","pith_inferences":["A natural extension is to treat the two coupled bands as a tunable beam-splitter for magnons: the $p\\parallel l$ coupling strength, linear in current, could swap excitations between the 300 GHz and 525 GHz modes in a cavity.","If the spin-orbit-torque conversion efficiency can be calibrated directly from the frequency-shift-versus-current curve, the same device becomes a quantitative probe of the out-of-plane spin polarization generated by mechanisms beyond the spin Hall effect.","The weaker tuning at finite wavevector suggests that a patterned or periodic heavy-metal layer could selectively tune only certain wavevectors, enabling wavevector-selective terahertz filtering.","The comparison with a Zeeman field implies that a DC-current-biased YFeO3 device could modulate terahertz radiation at the current modulation rate, which might be exploited for terahertz communication encoding."],"forward_implications":["At $q=0$, current densities just below self-oscillation shift the low-frequency band by +85.2 GHz for $p\\parallel x$, -106 GHz for $p\\parallel y$, and -158.1 GHz for $p\\parallel z$, with corresponding shifts of the high-frequency band.","At finite wavevector the tuning persists but weakens: at $q=0.0167$ nm$^{-1}$ the $p\\parallel z$ case still shifts the bands by -52.1 GHz and -90 GHz.","Standing-wave modes inherit the electrically shifted frequencies, so a confined antiferromagnetic cavity can emit tunable sub-terahertz radiation through magnetization precession.","Frequency tuning by spin current is nonlinear and the paper finds it several times more efficient than tuning by an equivalent external magnetic field.","The sign and size of the shifts depend on polarization direction, giving a three-axis electrical control knob for magnon band structure."],"supporting_citations":[{"why":"Provides the canted orthoferrite YFeO3 platform and its anisotropic long-range magnon transport, motivating the tunable device.","marker":"[19]"},{"why":"Supplies the framework for antiferromagnetic oscillators driven by spin currents with arbitrary spin polarization directions.","marker":"[22]"},{"why":"Establishes optical spin-orbit torque generation in heavy-metal heterostructures, used here to excite the spin waves.","marker":"[26]"},{"why":"Provides the antiferromagnetic equations of motion used in Eq. (2).","marker":"[31]"},{"why":"Supplies the damping-like spin-orbit torque form used throughout the analysis.","marker":"[32]"},{"why":"Gives YFeO3 anisotropy and NMR-determined spin structure parameters used in the calculation.","marker":"[33]"},{"why":"Provides YFeO3 material parameters and the coherent terahertz precession and emission framework used for detection.","marker":"[34]"},{"why":"Supplies the limiting spin-wave velocity $c_c$ entering the dispersion relation.","marker":"[35]"}],"fun_headline_variants":["Spin-orbit torque re-tunes terahertz spin-wave bands","Three spin polarizations shift THz spin waves by 34%","Canted antiferromagnet: spin currents tune THz waves","Electrical control of terahertz spin waves in AFM","Polarization-dependent torque steers AFM spin-wave bands"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The predicted frequency shifts assume that a given charge current produces the effective magnetic field strengths the paper quotes, up to about 0.7 T for the highest quoted current density; if the real conversion is weaker, every tuning range shrinks in proportion.","fun_headline_variants_meta":{"raw":{"variants":["Spin-orbit torque re-tunes terahertz spin-wave bands","Three spin polarizations shift THz spin waves by 34%","Canted antiferromagnet: spin currents tune THz waves","Electrical control of terahertz spin waves in AFM","Polarization-dependent torque steers AFM spin-wave bands"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.00024,"raw_usage":{"total_tokens":1500,"prompt_tokens":907,"completion_tokens":593,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":523,"completion_tokens_details":{"reasoning_tokens":505}},"tokens_in":523,"tokens_out":593,"duration_ms":6376,"temperature":1.0,"reasoning_tokens":505,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-12T16:35:04.368815+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the low-frequency standing-wave mode at $q=0.0167$ nm$^{-1}$ in a Pt/YFeO3 Hall bar under a DC current of $1.2\\times10^{12}$ A/m$^2$ with the polarization along $y$. The paper predicts a shift of $-38.6$ GHz; observing no comparable shift would show the tuning mechanism is much weaker than claimed.","supporting_citations":[{"cited_title":"Anisotropic long -range spin transport in canted antiferromagnetic orthoferrite YFeO3","cited_arxiv_id":null,"evidence_quote":"Provides the canted orthoferrite YFeO3 platform and its anisotropic long-range magnon transport, motivating the tunable device."},{"cited_title":"Antiferromagnetic Oscillators Driven by Spin Currents with Arbitrary Spin Polarization Directions","cited_arxiv_id":null,"evidence_quote":"Supplies the framework for antiferromagnetic oscillators driven by spin currents with arbitrary spin polarization directions."},{"cited_title":"Optical spin -orbit torque in heavy metal -ferromagnet heterostructures","cited_arxiv_id":null,"evidence_quote":"Establishes optical spin-orbit torque generation in heavy-metal heterostructures, used here to excite the spin waves."},{"cited_title":"Phenomenology of current -induced dynamics in antiferromagnets","cited_arxiv_id":null,"evidence_quote":"Provides the antiferromagnetic equations of motion used in Eq. (2)."},{"cited_title":"The m can be expressed regarding l by taking the cross product of l to equations 2a: 1~ ( )a  − m l l D l (3) By inserting Eq","cited_arxiv_id":null,"evidence_quote":"Supplies the damping-like spin-orbit torque form used throughout the analysis."},{"cited_title":"Spin pumping and spin -transfer torques in antiferromagnets","cited_arxiv_id":null,"evidence_quote":"Gives YFeO3 anisotropy and NMR-determined spin structure parameters used in the calculation."},{"cited_title":"NMR observation of the spin structure and field induced spin reorientation in YFeO 3","cited_arxiv_id":null,"evidence_quote":"Provides YFeO3 material parameters and the coherent terahertz precession and emission framework used for detection."},{"cited_title":"Coher ently controlled spin precession in canted antiferromagnetic YFeO3 using terahertz magnetic field","cited_arxiv_id":null,"evidence_quote":"Supplies the limiting spin-wave velocity $c_c$ entering the dispersion relation."}],"review_version":1}