{"id":"ccc9795d-a41b-449e-a375-2b64491091b7","arxiv_id":"2607.09256","paper_version":1,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":6.0,"correctness_risk":"low","formal_verification":"none","parameter_count":3,"one_line_summary":"THz radiation induces gate-tunable NLHE, NLL, and NLD currents in 2D tellurene that match LPGE phenomenology and arise from skew scattering, side jump, and Berry curvature dipole.","lead":"Terahertz light drives second-order dc currents in 2D tellurene, including a nonlinear Hall effect, that reverse with gate voltage and grow strongly on cooling. The work maps these currents onto photogalvanic responses and attributes them to skew scattering, side jumps, and Berry curvature dipole.","discovery_kind":"extension","skeptic_critique":{"model":"grok-4.5","headline":"No significant objection identified beyond the reader's already-flagged skew-dominance estimate.","rationale":"The Reader correctly isolates the only assumption that is not directly constrained by the data: the claim that conventional skew scattering dominates rests on an order-of-magnitude estimate whose disorder parameters are never measured. All other elements of the strongest claim—C1 phenomenology, quadratic intensity scaling, Stokes-parameter decomposition into NLH/NLL/NLD, gate-voltage sign reversal, and temperature enhancement—are independently corroborated by multiple figures and by the matching microscopic expressions. Because that single soft spot was already flagged and does not undermine the experimental observations or the phenomenological mapping, no further adjustment of the CONDITIONAL verdict is warranted.","tokens_in":20787,"tokens_out":488,"duration_ms":4516,"concrete_test":"Extract mobility and carrier density from the same Hall-bar devices at the gate voltages used for photocurrent (Figs. 1c,d and 3), convert to τ_tr and ε_F, then recompute the expected high-frequency conductivity factor σ(ω) = σ_0/(1+ω²τ_tr²) for the three laser frequencies; if the measured J/P_s ratios track this factor within ~30 % once the reststrahlen refractive-index correction is included, the Drude-origin and mechanism hierarchy remain intact.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim (THz-driven second-order currents in C1 tellurene decompose into NLH/NLL/NLD ≡ LPGE channels, gate-tunable with opposite e/h signs, and arise from the standard set of mechanisms) is internally consistent with the polarization, intensity, gate, temperature and frequency data (Eqs. 3–4, 11, 15, 23–26; Figs. 2–7). The only soft point that could still affect the microscopic half of the claim is the unquantified ratio j_skew/j_BCD ∼ ε_F/(N_d|U|) (Sec. V after Eq. 20). That estimate is already identified by the Reader as the weakest assumption; no stronger, independent load-bearing flaw (e.g., symmetry misassignment, intensity non-linearity, or channel-mapping inconsistency) appears in the full text.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.5","summary":"The manuscript reports THz-driven second-order dc currents in C1-symmetric 2D tellurene Hall bars, measured along and perpendicular to the c-axis. Polarization, intensity, gate, temperature and frequency dependences are shown to match the six independent LPGE coefficients of Eqs. (3)–(4). These are rewritten as NLHE, NLL and NLD transport channels (Eqs. 23–26). A semiclassical Boltzmann theory supplies skew-scattering (Eq. 11), Berry-curvature-dipole (Eq. 15) and side-jump contributions; the data are argued to be consistent with all three, with conventional skew scattering suggested to dominate on the basis of an order-of-magnitude estimate after Eq. (20). Currents reverse sign across the charge-neutrality point and grow strongly on cooling and on lowering frequency.","tokens_in":20975,"tokens_out":955,"duration_ms":9257,"significance":"The work cleanly demonstrates that contactless, polarization-resolved THz excitation can resolve the full set of second-order conductivities in a low-symmetry 2D semiconductor without a linear dc background, and that the same tensor underlies both nonlinear transport and LPGE. The experimental trends (gate sign reversal, T and ω dependence) are robust and the phenomenological mapping is transparent. If the microscopic assignment can be sharpened, the paper would provide a useful template for separating intrinsic and extrinsic nonlinear responses in other non-centrosymmetric 2D materials.","major_comments":[{"comment":"Sec. V after Eq. (20): the claim that conventional skew scattering dominates rests on j_skew/j_BCD ∼ ε_F/(N_d|U|) with ε_F ≈ 50 meV and an unquantified assertion that the ratio exceeds unity. No independent estimate of N_d or |U| (or of the relative weight of coherent skew, side-jump and BCD) is supplied. Because the abstract and Sec. VI present this microscopic origin as a result rather than a plausible scenario, either a quantitative bound (mobility, residual resistivity, or disorder model) or a clear statement that the assignment remains an assumption is required.","section":null},{"comment":"Sec. VI and insets of Fig. 3: the observed rise of J/P_s with decreasing frequency is attributed to a frequency-dependent refractive-index factor near the reststrahlen band that converts P_s into |E|^2. Without a measured or calculated conversion factor, the microscopic prediction j ∝ σ(ω) cannot be tested. A short estimate of the Fresnel factor (or an explicit statement that the frequency trend is only qualitative) is needed to keep the comparison with Eqs. (11) and (15) load-bearing.","section":null}],"minor_comments":[{"comment":"The Nonlinear Diagonal (NLD) current is introduced as a new effect (Eqs. 23, 26–27). A one-sentence comparison with existing literature on second-order diagonal responses would help readers place the terminology.","section":null},{"comment":"Figs. 5 and 7: several panels multiply J_L2 by 10 for visibility; the factor should be stated uniformly in every caption that uses it.","section":null},{"comment":"Notation for the six coefficients switches between J^{c,a}_{0,L1,L2} and C_{NLL,NLH,NLD}; a compact table mapping the two bases would improve readability of Sec. VI.","section":null},{"comment":"Sample #B shows a slight offset of the current-inversion point from U_G = 0 (Fig. 5f); the mixed-carrier explanation is plausible but could be supported by a brief two-carrier estimate.","section":null},{"comment":"A few typographical issues remain (e.g., “CONSIDERA TION”, “TECHNIQUE”, missing spaces in figure labels).","section":null}],"recommendation":"minor_revision","confidential_remarks":"The central experimental claim is solid and the phenomenology is correctly applied. The only soft points are the unquantified skew-dominance estimate and the uncalibrated frequency conversion; both are fixable by modest text changes and do not require new data. Fit for a specialized condensed-matter journal is good."},"author_rebuttal":null,"desk_editor":{"model":"grok-4.5","letter":"The useful part of this paper is experimental and phenomenological. They drive 2D tellurene Hall bars with linearly polarized THz (0.6–2.54 THz), measure the dc current both along and perpendicular to the c-axis, and show that the polarization dependence decomposes into the six independent C1 coefficients (J0, JL1, JL2 for each direction). They then rewrite those coefficients as the NLHE, NLL and NLD channels and demonstrate the exact equivalence to the LPGE Stokes terms. Intensity is quadratic, the currents reverse with gate voltage across the CNP, grow by ~100× on cooling to 4.2 K, and rise as frequency drops. Two samples, room-temperature and cryogenic data, pulsed and cw sources—all consistent with the C1 forms (Eqs. 3–4) and the standard Boltzmann expressions for skew, side-jump and BCD (Eqs. 11, 15).\n\nWhat is new is the simultaneous resolution of the three channels plus the explicit LPGE–transport dictionary under C1. NLHE itself and THz LPGE in tellurene were already reported (their Refs. 7, 23, 24). The NLD term is just the remaining independent piece required by C1; naming it is bookkeeping, not a discovery.\n\nSoft spots are real but limited. The claim that conventional skew dominates rests on the order-of-magnitude ratio ~εF/(Nd|U|) with εF≈50 meV and no measured disorder strength; that is an assumption, not a result. They also never extract absolute second-order conductivities because the local |E| is not calibrated (refractive-index factor near the reststrahlen band is left open). Frequency dependence is therefore only qualitative. None of this breaks the central observations or the channel mapping.\n\nMath and citations look standard and honest; self-cites are to their own prior THz work on the same material. The paper is for people who care about nonlinear transport or THz rectification in low-symmetry 2D systems. It deserves a serious referee. I would read it, cite the experimental decomposition, and not lean on the microscopic ranking until someone measures Nd or |U|.","headline":"Solid THz experiment that cleanly maps all three second-order channels in C1 tellurene onto LPGE; the data hold, the skew-dominance claim is only an estimate.","tokens_in":21719,"tokens_out":562,"would_cite":true,"duration_ms":6025,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.5","headline":"THz radiation drives gate-tunable second-order currents in 2D tellurene that decompose into nonlinear Hall, longitudinal and diagonal channels.","keywords":["nonlinear Hall effect","2D tellurene","terahertz photogalvanic effect","Berry curvature dipole","skew scattering","side jump","gate-tunable transport","C1 symmetry"],"falsifier":"Measure the same six current coefficients in a tellurene flake whose impurity density has been independently quantified (for example by residual-resistivity ratio or deliberate doping) and check whether the observed magnitude tracks the predicted 1/τ or 1/τ^{2} scaling of conventional versus coherent skew scattering.","tokens_in":21633,"feed_emoji":"⚡","tokens_out":690,"duration_ms":7060,"temperature":0.7,"pith_summary":"This paper shows that linearly polarized terahertz radiation generates dc currents in two-dimensional tellurene Hall bars that are quadratic in the ac electric field and depend on its orientation. The currents arise because the flakes have only C1 symmetry, so all second-order conductivity components are allowed. By rotating the field and measuring both along and perpendicular to the crystal c-axis, the authors resolve three transport channels—nonlinear Hall, nonlinear longitudinal and nonlinear diagonal—and prove they are exactly the same as the familiar linear photogalvanic contributions. Every channel reverses when the gate voltage switches the carriers from electrons to holes, grows by roughly two orders of magnitude upon cooling to 4.2 K, and strengthens as the radiation frequency is lowered. A combined phenomenological and semiclassical theory accounts for the data with three microscopic processes: skew scattering, side jumps and the Berry curvature dipole. The work therefore converts a contactless optical measurement into a practical probe of nonlinear transport that works from cryogenic temperatures up to room temperature.","feed_headline":"THz light drives gate-tunable nonlinear currents in 2D tellurene","feed_subtitle":"Polarization scans map Hall, longitudinal and diagonal channels that reverse with carrier type","key_machinery":"The equivalence between the six independent LPGE coefficients (J0, JL1, JL2 along a and c) and the three nonlinear-transport vectors (NLH, NLL, NLD) given by the linear relations in Eqs. (24)–(26). This identity converts a polarization scan of a photocurrent into a complete map of the second-order conductivity tensor.","core_discovery":"Terahertz-driven dc currents in C1-symmetric 2D tellurene are second-order responses that decompose cleanly into nonlinear Hall, nonlinear longitudinal and nonlinear diagonal channels; these channels are identical to the linear photogalvanic contributions, are gate-tunable with opposite signs for electrons and holes, and are generated by the combination of skew scattering, side-jump and Berry-curvature-dipole mechanisms.","pith_inferences":[],"forward_implications":[],"fun_headline_variants":["THz fields drive gate-tunable nonlinear Hall currents in 2D tellurene","Second-order THz transport splits into Hall, longitudinal and diagonal channels","Gate voltage flips electron-hole signs of THz nonlinear currents in tellurene","THz radiation maps NLHE, NLL and NLD responses in C1-symmetric tellurene","Skew scattering, side-jump and Berry dipole yield THz nonlinear currents"],"cache_read_input_tokens":16512,"weakest_assumption_plain":"The assignment of conventional skew scattering as the dominant microscopic source rests on an order-of-magnitude estimate that uses an unmeasured disorder strength, so the ranking of mechanisms is assumed rather than independently verified.","fun_headline_variants_meta":{"raw":{"variants":["THz fields drive gate-tunable nonlinear Hall currents in 2D tellurene","Second-order THz transport splits into Hall, longitudinal and diagonal channels","Gate voltage flips electron-hole signs of THz nonlinear currents in tellurene","THz radiation maps NLHE, NLL and NLD responses in C1-symmetric tellurene","Skew scattering, side-jump and Berry dipole yield THz nonlinear currents"]},"model":"grok-4.5","effort":"low","cost_usd":0.00513,"raw_usage":{"total_tokens":1463,"prompt_tokens":816,"num_sources_used":0,"completion_tokens":92,"cost_in_usd_ticks":51300000,"prompt_tokens_details":{"text_tokens":816,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":555,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":816,"tokens_out":92,"duration_ms":5585,"temperature":1.0,"reasoning_tokens":555,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-07-13T04:20:55.952033+00:00","model_set":{"reader":"grok-4.5"},"falsifier":"Measure the same six current coefficients in a tellurene flake whose impurity density has been independently quantified (for example by residual-resistivity ratio or deliberate doping) and check whether the observed magnitude tracks the predicted 1/τ or 1/τ^{2} scaling of conventional versus coherent skew scattering.","supporting_citations":[],"review_version":1}