{"id":"4c8abc6b-40f6-44bf-bdf5-1afd2c676b3d","arxiv_id":"2505.06144","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":2,"one_line_summary":"At the light-induced gap closing in monolayer Pt2HgSe3, the spin Edelstein conductivity jumps while the orbital Edelstein susceptibility drops to zero, offering a transport probe of the transition.","lead":"This paper calculates how circularly polarized light changes the electronic bands of monolayer Pt2HgSe3 and predicts that current-induced spin and orbital responses mark the light-induced transition to a semimetal. It proposes the Edelstein effect as a measurable fingerprint of photoinduced topological changes in two-dimensional materials.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Interband 'spin' Edelstein conductivity is computed with sublattice-pseudospin Pauli matrices, not the conserved spin label; as the physical spin operator has no interband matrix elements, the reported discontinuity is not an electronic spin response.","rationale":"A good-faith reading is that the paper is a model study claiming that the interband spin Edelstein conductivity jumps at the light-induced gap-closing point, providing a transport signature of the topological transition. The most load-bearing requirement is that the quantity computed as 'spin Edelstein' is actually the electronic spin response. It is not: Eq. (1) is block diagonal in the spin label s, and σ are explicitly pseudospin/sublattice Pauli matrices. Consequently S_z is proportional to the identity in each spin block, so S_z has zero interband matrix elements. The interband contributions in Appendix B are matrix elements of σ_i, not of S_i. They produce the discontinuity in Fig. 2(d)-(f), but they describe pseudospin coherence. Replacing O with the physical spin operator makes the interband term vanish identically, removing the headline signature. The reader's concern about the validity of the high-frequency Floquet expansion at Δd/Δso = ±1 is legitimate, and the paper should also supply material parameters and a description of the numerical regularization, but that concern is secondary: even a fully valid Floquet Hamiltonian would not turn a pseudospin response into a spin response. There are also smaller internal inconsistencies, such as Eq. (12) retaining an uncancelled band index n in Lz_n, but they are not needed for the central objection. Because the central experimental claim is built on the misidentified observable, the paper as written does not support its central conclusion.","tokens_in":10552,"tokens_out":16918,"duration_ms":190850,"concrete_test":"Recompute χ^{spin,inter}_{ij} from Eq. (8) with the observable S_z = (ℏ/2) s_z ⊗ I instead of σ_z, and similarly for in-plane components, while keeping all other definitions unchanged. Because S_i is block diagonal in the spin label s and the Hamiltonian does not mix spins, the interband matrix elements O^z_{mn} vanish for m ≠ n; verify that the μ = 0 interband spin response shown in Fig. 2(d) becomes exactly zero and that no discontinuity remains at Δd/Δso = −1. If the authors instead intend σ_i as the observable, the experiment proposed in Sec. IV measures sublattice polarization, not spin polarization.","verdict_should_be":"REJECT","load_bearing_attack":"Sec. II.A states that the σ_i are Pauli matrices acting on the pseudospin (sublattice) space and that s = ±1 labels spin. The Hamiltonian in Eq. (1) is block diagonal in s, so the physical spin operator in each spin sector is S_z = (ℏ/2) s I_2, with zero in-plane spin components. This operator has no off-diagonal matrix elements between the two bands. Nevertheless, Appendix B (Eqs. B1g-i) and the Kubo evaluation identify the 'spin' operator with the sublattice Pauli matrices σ_i. The interband spin Edelstein susceptibility, which is the source of the claimed discontinuity at Δd/Δso = −1 in Figs. 2(d)-(f), is therefore a pseudospin coherence response, not a response of the electronic spin. Replacing the observable with the physical spin operator S_i = s_i ⊗ I forces the interband term in Eq. (8) to vanish identically, so the headline signature disappears. The paper may describe a pseudospin Edelstein effect, but it does not compute the spin Edelstein effect it advocates as an experimentally accessible probe.","agreement_with_reader":"disagree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript studies a two-band Dirac model for monolayer jacutingaite Pt2HgSe3 under irradiation by circularly polarized light. A high-frequency Floquet expansion maps the light to a valley-dependent mass term Δd added to the spin-orbit mass, so that Δd/Δso = ±1 closes the gap for one spin-valley flavor. Using Kubo linear response, the authors compute spin and orbital Edelstein susceptibilities and report that the interband spin susceptibility is discontinuous and the orbital susceptibility vanishes at the gap-closing point. They propose these features as a transport-based probe of the light-induced topological transition that does not require computing Chern numbers.","tokens_in":10822,"tokens_out":9875,"duration_ms":108109,"significance":"The idea of using current-induced polarization to detect light-induced band inversions is attractive, and the algebra connecting the mass term to the response is straightforward. However, the central spin Edelstein result relies on identifying the sublattice pseudospin Pauli matrices with the physical spin operator. Because the physical spin operator has no interband matrix elements in this model, the reported interband spin discontinuity is an artifact of that identification. The orbital Edelstein channel is physically well defined, but the claimed universal spin signature, which is the paper's main advertised result, is not a spin response. The paper is therefore not a sound basis for the stated spintronic conclusions; a reframing as a pseudospin Edelstein study would substantially weaken the experimental accessibility claims.","major_comments":[{"comment":"Section II.A defines σ_i as Pauli matrices on the pseudospin (sublattice) space and s=±1 as the spin label. The Hamiltonian in Eq. (1) is block diagonal in s, so within each spin sector the physical spin operator is S_z=(ℏ/2)s I_2 and the in-plane spin operators have no matrix elements at all; consequently every interband matrix element O^spin_{mn} of the physical spin vanishes. Nevertheless, the Kubo evaluation in Appendix B, Eqs. (B1g)-(B1i), uses the sublattice Pauli matrices σ_i as the 'spin' operator, producing nonzero interband matrix elements. The interband spin Edelstein susceptibility in Eq. (8) and the discontinuity in Fig. 2(d)-(f) are therefore sublattice-pseudospin coherence responses, not responses of the electronic spin. Replacing O with the physical spin operator forces the interband term to zero and removes the headline signature claimed in the abstract and in Sec. IV.","section":"Sec. II.A, II.B, and Appendix B"},{"comment":"Appendix A replaces the driven Hamiltonian by the static mass term Δd=e^2 A0^2 v_F^2/ω_d using the leading-order high-frequency expansion in Eq. (A2). The paper locates the transition at Δd/Δso=±1. At that point the dimensionless drive parameter is eA0 v_F/ω_d = sqrt(Δso/ω_d); the paper never specifies ω_d/Δso or verifies that this parameter is small. For a strong-SOC material such as jacutingaite with Δso on the scale of tens to hundreds of meV and off-resonant frequencies in the infrared-to-visible range, this ratio can be order one, in which case the truncation in Eq. (A2) is uncontrolled and higher-order Floquet corrections can shift or remove the gap closing. The predicted response signatures therefore do not necessarily describe the actual Floquet state at the nominal transition.","section":"Appendix A and Eq. (A4)"},{"comment":"The interband Kubo integrand for the pseudospin operator behaves as O(p)/(ε_n-ε_m)^2 ~ 1/k^2 at large momentum for all values of Δd, so after the d^2k integration it is logarithmically divergent in the absence of a cutoff. The paper uses a linearized Dirac Hamiltonian valid only near K and does not specify a momentum cutoff, a subtraction, or a regularization scheme. The finite discontinuity plotted in Fig. 2 is therefore cutoff-dependent and cannot be claimed as a universal signature unless the regularization is specified and shown not to affect the qualitative jump.","section":"Sec. III and Eq. (8)"}],"minor_comments":[{"comment":"The word 'vallyes' should be 'valleys' in the opening sentence of Sec. III.","section":"Sec. III"},{"comment":"The affiliation list contains 'Faculty of of Physics'; the duplicated 'of' should be corrected.","section":"Author affiliation"},{"comment":"The paper sets ℏ=kB=me=e=1 but leaves lifetimes in eV; the text should state how this unit system maps to physical SI units for the plotted quantities.","section":"Sec. II.B"},{"comment":"The caption refers to Δd/Δso as the 'normalized sublattice asymmetry parameter', but Δd is a light-induced mass term rather than a sublattice asymmetry; the terminology should be revised for clarity.","section":"Fig. 2 caption"}],"recommendation":"reject","confidential_remarks":"The operator-identification error is fundamental, not a matter of notation, because the physical spin operator has vanishing interband matrix elements in this model. I would only reconsider if the authors explicitly reframe the manuscript as a pseudospin Edelstein study and thoroughly address the Floquet and ultraviolet issues; as written, the main claim is not correct."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Quick take: the paper's headline result is not a spin Edelstein effect. The model is a spin-diagonal two-band Hamiltonian, so the true spin operator in each spin sector is s⊗I. It has no interband matrix elements. The interband 'spin' conductivity that produces the discontinuity in Figs. 2(d)-(f) is computed with sublattice Pauli matrices; it is a pseudospin coherence response. The intraband spin components are similarly momentum-dependent only because σ is treated as spin. So the central claim — a transport-accessible spin probe of the topological transition — does not follow.\n\nWhat the paper does well: the algebra is clean, the Floquet derivation in Appendix A is standard, and the orbital Edelstein part, computed from the Berry curvature, is internally consistent. The two-band model for jacutingaite is reasonable, and the valley-contrasting gap-closing analysis is correct. If the 'spin' label were replaced by 'sublattice pseudospin', the calculation would be a minor but valid model study of pseudospin Edelstein responses.\n\nThe soft spots: first, the physical spin operator in the model is diagonal and constant, so all spin Edelstein components — intra and inter — are mislabeled. This is not a small oversight; it changes the observable. Second, as the reader noted, at Δd/Δso = ±1 the Floquet high-frequency expansion is not checked; the drive-induced mass is of the same order as the intrinsic SOC, so the effective Hamiltonian may not be valid there. That issue is real but secondary once the operator error is fixed.\n\nReadership: people working on pseudospin or orbital Edelstein effects might find the formalism useful, but anyone interested in spin transport in jacutingaite should be wary. I would not cite this as a spin Edelstein result.\n\nRecommendation: desk reject. The central observable is misidentified, so the paper's advertised finding cannot be salvaged without rewriting it as a pseudospin-Edelstein paper, which would be a much weaker result. A referee would catch this immediately.","headline":"The paper's central 'spin' Edelstein discontinuity is actually a sublattice pseudospin response: the authors define σ as sublattice Pauli matrices but then use σ as the spin operator, so the headline result is not a physical spin effect.","tokens_in":11322,"tokens_out":4139,"would_cite":false,"duration_ms":43807,"reading_group":"no","serious_thinker":"no","would_accept_peer_review":false},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"Edelstein response pinpoints light-driven topological switch in Pt2HgSe3","keywords":["Edelstein effect","Floquet engineering","jacutingaite Pt2HgSe3","quantum spin Hall insulator","topological phase transition","spin-orbit coupling","orbital magnetization","semimetal"],"falsifier":"A direct time-dependent numerical simulation of the full driven Hamiltonian, without the high-frequency effective-mass approximation, could settle whether the gap actually closes at Δd/Δso = ±1 and whether the spin Edelstein conductivity really shows a discontinuity there; if the exact Floquet bands remain gapped at that point or the conductivity varies smoothly, the predicted signature would not survive.","tokens_in":10397,"feed_emoji":"🌀","tokens_out":4628,"duration_ms":43425,"temperature":0.7,"pith_summary":"This paper claims that the spin and orbital Edelstein effects—electric-field-induced spin and orbital polarizations—can serve as experimental probes of light-induced topological phase transitions in monolayer jacutingaite Pt2HgSe3. In the effective low-energy Dirac model, circularly polarized light adds a valley-contrasting mass term that can cancel the intrinsic spin-orbit mass for one spin species in one valley, closing the gap and creating a spin-polarized semimetal. The paper identifies two universal transport signatures of this transition: a pronounced discontinuity in the interband spin Edelstein conductivity and a vanishing orbital Edelstein susceptibility. These signatures do not require computing Chern numbers, so they offer a direct, transport-based way to locate the topological boundary.","feed_headline":"Edelstein response pinpoints light-driven topological switch","feed_subtitle":"In monolayer Pt2HgSe3, a spin response discontinuity marks the gap-closing transition to a semimetal.","key_machinery":"The load-bearing objects are the spin-valley-resolved Dirac mass term $\\Delta_{\\zeta,s} = \\zeta s \\Delta_{\\mathrm{so}} + \\zeta \\Delta_d$, the Kubo formula for the Edelstein conductivity tensor, and the orbital angular momentum operator defined through the Berry curvature (orbital magnetic moment). The argument works by evaluating the intraband and interband contributions separately: the interband spin response remains finite at charge neutrality and is discontinuous at the gap-closing point, while the orbital Edelstein response vanishes there because of symmetry and the structure of the orbital matrix elements. The Floquet high-frequency expansion (Eqs. A2–A4) supplies the light-induced mass $\\Delta_d = e^2 A_0^2 v_F^2 / \\omega_d$, which is the tunable knob for driving the system through the transition.","core_discovery":"The central discovery is that the transition from the quantum spin Hall insulating phase to a spin- and valley-selective semimetallic phase is encoded in the Edelstein response functions of the light-dressed Dirac Hamiltonian $H_{\\zeta,s} = v_F(\\zeta k_x \\sigma_x + k_y \\sigma_y) + (\\zeta s \\Delta_{\\mathrm{so}} + \\zeta \\Delta_d)\\sigma_z$. For each valley and spin species, the mass term $\\Delta_{\\zeta,s} = \\zeta s \\Delta_{\\mathrm{so}} + \\zeta \\Delta_d$ vanishes when $\\Delta_d/\\Delta_{\\mathrm{so}} = \\pm 1$, closing the gap for exactly one spin flavor in one valley. At that critical point, the interband spin Edelstein conductivity develops a pronounced discontinuity, the intraband spin response changes sharply, and the orbital Edelstein susceptibility vanishes. The paper argues that these features are universal, valley-contrasting, and robust against doping, and that they provide a direct transport-based diagnostic of the photoinduced topological transition.","pith_inferences":["Because the proof uses a generic two-band Dirac Hamiltonian with a tunable mass, the same discontinuity and vanishing signatures should appear in other gapped Dirac materials with a photoinduced mass term, such as silicene or transition-metal dichalcogenides; this is an extrapolation beyond the paper's explicit claim.","The vanishing orbital Edelstein susceptibility at the transition may provide a Berry-curvature-sensitive observable that is experimentally easier to access than the anomalous Hall effect, but the paper does not make this connection explicitly.","If the high-frequency Floquet expansion fails quantitatively at the critical drive strength, the signatures could still survive but at a shifted drive amplitude, which would make the effect a useful empirical probe even if the precise mass formula changes.","A direct test could be performed by measuring current-induced spin polarization (e.g., via Kerr rotation) in a Pt2HgSe3 monolayer while sweeping the laser intensity across the predicted critical value."],"forward_implications":["Tuning the drive amplitude or frequency lets one switch monolayer jacutingaite between the quantum spin Hall insulating phase and a spin-polarized semimetal without modifying the material itself.","The Edelstein response gives an all-electrical probe of the topological transition, since it can be read from transport measurements without extracting Chern numbers.","The signatures are valley-selective, so they reveal which valley and spin species undergo gap closing, enabling spin-valley resolved diagnostics.","The interband scattering time controls the magnitude and anisotropy of the spin Edelstein conductivity at the transition, so lifetime engineering can enhance the observable signal."],"supporting_citations":[{"why":"Establishes monolayer jacutingaite as a large-gap quantum spin Hall insulator with strong spin-orbit coupling, providing the physical system and its intrinsic mass scale.","marker":"[5]"},{"why":"Proposes an RKKY-based probe of topological phases in the same material; the paper compares its Edelstein approach against this alternative.","marker":"[12]"},{"why":"Provides prior treatment of photoinduced phases in jacutingaite monolayers, which motivates the light-driven mass picture used here.","marker":"[14]"},{"why":"Defines the original spin-polarization effect that the paper generalizes to a probe of topological transitions.","marker":"[15]"},{"why":"Supplies the Kubo linear-response formalism used to compute the Edelstein conductivity tensor.","marker":"[18]"},{"why":"Gives the Berry-phase/orbital-magnetization relation used to define the orbital Edelstein response.","marker":"[21]"},{"why":"Provides the high-frequency Floquet expansion that yields the light-induced mass term Δd used in the effective Hamiltonian.","marker":"[26]"},{"why":"Shows a similar photoinduced gap-closing transition in silicene, whose mass-cancellation mechanism the paper applies to jacutingaite.","marker":"[28]"}],"fun_headline_variants":["Edelstein spin jump flags light-driven gap closure in jacutingaite","Orbital Edelstein vanishes at topological transition in Pt2HgSe3","Discontinuity in spin Edelstein conductivity marks semimetal onset","Light-controlled topological switch visible via Edelstein response","Jacutingaite under light: Edelstein probe of phase change"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The high-frequency Floquet expansion replaces the periodically driven system by the static effective mass Δd, and the paper locates the transition at Δd/Δso = ±1, where this mass is comparable to the intrinsic spin-orbit mass, without explicitly checking that the perturbative expansion remains valid at that drive strength.","fun_headline_variants_meta":{"raw":{"variants":["Edelstein spin jump flags light-driven gap closure in jacutingaite","Orbital Edelstein vanishes at topological transition in Pt2HgSe3","Discontinuity in spin Edelstein conductivity marks semimetal onset","Light-controlled topological switch visible via Edelstein response","Jacutingaite under light: Edelstein probe of phase change"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000245,"raw_usage":{"total_tokens":1556,"prompt_tokens":987,"completion_tokens":569,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":603,"completion_tokens_details":{"reasoning_tokens":473}},"tokens_in":603,"tokens_out":569,"duration_ms":5560,"temperature":1.0,"reasoning_tokens":473,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-15T22:47:39.374992+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A direct time-dependent numerical simulation of the full driven Hamiltonian, without the high-frequency effective-mass approximation, could settle whether the gap actually closes at Δd/Δso = ±1 and whether the spin Edelstein conductivity really shows a discontinuity there; if the exact Floquet bands remain gapped at that point or the conductivity varies smoothly, the predicted signature would not survive.","supporting_citations":[{"cited_title":"Marrazzo, M","cited_arxiv_id":null,"evidence_quote":"Establishes monolayer jacutingaite as a large-gap quantum spin Hall insulator with strong spin-orbit coupling, providing the physical system and its intrinsic mass scale."},{"cited_title":"Yarmohammadi, S","cited_arxiv_id":null,"evidence_quote":"Proposes an RKKY-based probe of topological phases in the same material; the paper compares its Edelstein approach against this alternative."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Defines the original spin-polarization effect that the paper generalizes to a probe of topological transitions."}],"review_version":1}