{"id":"c280a2d7-af1b-4cf8-9f33-fa1f3d55ca2b","arxiv_id":"2607.26804","paper_version":1,"verdict":"ACCEPT","confidence":"HIGH","novelty_score":4.0,"correctness_risk":"low","formal_verification":"none","parameter_count":2,"one_line_summary":"Photon-energy and polarization-dependent ARPES plus DFT disentangle and assign bulk and surface states on both DH and KL terminations of PtBi2(0001), with orbital character matching polarization trends.","lead":"ARPES and DFT map bulk versus surface bands on both terminations of trigonal PtBi2(0001). The map is needed because surface Fermi arcs are the proposed hosts of the material’s reported topological surface superconductivity.","discovery_kind":"extension","skeptic_critique":{"model":"grok-4.5","headline":"No significant objection identified","rationale":"This is a characterization/atlas paper whose strongest claim is organizational and qualitative, not a precision location of Weyl nodes or a proof of surface superconductivity. The experimental design (two terminations, broad VUV range, s/p polarization, two beamlines/geometries) plus orbital-resolved slab calculations supplies redundant cross-checks that keep the bulk/surface separation intact even when individual DFT energies are offset by ~0.2 eV or when one steep near-EF feature is mixed. No internal inconsistency, circular definition of surface states, or undisclosed methodological break appears. The reader's ACCEPT / low correctness_risk / HIGH confidence judgment is therefore unchanged; the noted weakest assumption is the standard caveat for this class of work and does not move the verdict.","tokens_in":13128,"tokens_out":415,"duration_ms":9390,"concrete_test":"Overlay the full hν=18–120 eV Fermi-surface stacks (Fig. S1) for both terminations and both polarizations; confirm that candidate surface features (DH 1,3,5,6; KL 1–3) stay fixed in (kx,ky) while bulk crossings move with kz. If any labeled surface state tracks kz by more than the stated broadening, the mixed-character assignments would need revision.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The reader's weakest assumption (kz broadening + GGA energy offsets for mixed bulk–surface labels, especially the KL near-EF steep band and the ~0.2 eV DH Dirac offset) is real but ordinary and already disclosed. It does not undercut the central claim: a multi-knob (hν, polarization, termination) atlas that disentangles bulk continua from surface features and finds qualitative agreement with semi-infinite Wannier spectral weight. Assignments rest on several independent experimental handles rather than a single free-electron kz map or an exact DFT energy match, so the coherent termination-resolved picture remains supported.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.5","summary":"The manuscript presents a VUV-ARPES and DFT study of trigonal non-centrosymmetric PtBi2(0001), aimed at disentangling bulk dispersions from surface states on the two cleave terminations (decorated-honeycomb, DH, and Kagome-like, KL). Photon-energy-dependent spectra are used to separate Γ-plane versus A-plane bulk features (notably Rashba-like branches near M and steeper A-plane bands), while surface spectral-weight calculations on semi-infinite Wannier slabs are compared to termination-resolved ARPES to assign several surface features, including the Fermi arc and a DH-only Dirac-like crossing at Γ. Orbital projections (Bi 6p) are then related to polarization-dependent intensity trends. The authors conclude that experiment and calculation agree sufficiently to give a coherent, termination-resolved picture of the surface electronic structure relevant to reported surface superconductivity.","tokens_in":13190,"tokens_out":1087,"duration_ms":28476,"significance":"If the assignments hold, the work supplies a practical multi-handle atlas (hν, polarization, termination) for a material in which surface-localized topological superconductivity has been claimed but remains experimentally contested. The combination of kz-sensitive bulk stacks, semi-infinite surface spectral weight, and orbital/polarization cross-checks is the right toolkit for this problem, and the side-by-side DH versus KL comparison fills a genuine gap left by prior Fermi-arc-focused studies. Strengths include systematic labeling of multiple surface features (1)–(7), explicit acknowledgment of kz broadening and residual energy offsets, and orbital-resolved calculations that give a concrete (if qualitative) account of polarization matrix-element trends. The result is incremental rather than transformative, but it is useful reference work for the PtBi2 community.","major_comments":[],"minor_comments":[{"comment":"Results, bulk bands / Fig. 2: The free-electron-like kz assignment (56 eV ~ Γ-plane, 18 eV ~ A-plane) is standard and consistent with the data, but the inner potential and the estimated kz-broadening window are never stated. A short sentence (or a note pointing to Fig. S1) would make the mapping reproducible.","section":"Results, Bulk bands; Fig. 2"},{"comment":"Results, surface states / Figs. 3–4: The DH Dirac-like crossing (feature 5) is ~0.2 eV deeper in experiment than in the surface calculation; the KL steep near-EF feature is described as mixed bulk–surface. Both points are already noted, but a brief quantitative summary of residual energy shifts across the labeled features would help readers judge assignment robustness without hunting through the text.","section":"Results, Surface states; Figs. 3–4"},{"comment":"Orbital character section / Eq. (1) and Fig. 6: The dipole-selection discussion correctly notes that ΓM is not a strict crystal mirror plane, yet still applies even/odd language. Clarifying that this is only a qualitative guide (and that final-state and photon-energy effects also matter) would avoid over-reading the polarization contrast, especially for the Rashba-like bulk bands that show little systematic polarization dependence.","section":"Orbital character and polarization dependence"},{"comment":"Fig. 2(e) green arrow and related text: The mixed bulk–surface character of the steep near-EF band on KL is important for Fermi-arc discussions; a cross-reference to the surface calculation panel (Fig. 4a) at that momentum would make the mixed assignment easier to verify.","section":"Fig. 2; Fig. 4"},{"comment":"Minor presentation: several figure captions and the main text refer to Supplemental Figs. S1–S6 that are not in the submitted main file; ensure they are complete and that energy/momentum scales and polarization labels are consistent with the main figures. Also fix small typos (e.g., “EXPERIMENT AL DET AILS”, “i-wave” spacing, author-name umlauts/encoding).","section":"Throughout / Experimental Details"},{"comment":"Introduction: The contested experimental status of surface superconductivity is summarized fairly; a single sentence stating that the present work does not itself address the gap or Tc would set expectations cleanly for readers coming from the SC literature.","section":"Introduction"}],"recommendation":"minor_revision","confidential_remarks":"Solid, useful ARPES+DFT atlas paper; no load-bearing technical failure. Fit is appropriate for a specialized condensed-matter / electronic-structure journal. Novelty is incremental (termination-resolved assignment and orbital/polarization cross-check) rather than a new topological claim; that is fine if the journal values careful characterization. Author overlap with prior theory (Vocaturo/Facio et al.) is disclosed by coauthorship and is not a circularity problem given the independent ARPES handles."},"author_rebuttal":null,"desk_editor":{"model":"grok-4.5","letter":"This is the clean reference map the PtBi2 surface-SC crowd has needed. Photon-energy series plus polarization on both DH and KL terminations, matched to semi-infinite Wannier spectral weight, let them label bulk continua versus surface features (including the Fermi arc and the DH Γ Dirac-like crossing) without hand-waving. That is the actual new result: concrete assignments and a coherent two-termination picture, not another claim of arcs or Weyl nodes (already in the cited record).\n\nThey do the work carefully. Γ-plane versus A-plane bulk features track hν as expected (56 eV vs 18 eV), surface weight persists across photon energy with matrix-element variation, and the orbital projections (especially pz on the Dirac crossing, in-plane weight on the deeper Γ intensity) line up with the s/p polarization trends. Hybridization dips at bulk crossings are noted rather than ignored. Citations are complete and fair; circularity is low because new spectra are compared to calculation, not defined by it.\n\nSoft spots are ordinary and disclosed. The DH Dirac sits ~0.2 eV deeper than GGA; some predicted KL surface weight is weak or off-range; VUV kz is broadened and free-electron-mapped. None of that breaks the central claim—the multi-knob consistency still holds. No invented entities, no load-bearing free parameters beyond the usual inner potential and overall energy alignment.\n\nWho it is for: anyone measuring or calculating surface states, arcs, or pairing on this material. It will not change the superconductivity debate by itself, but it stops people from mis-assigning bulk intensity as surface or mixing terminations. I would send it to referees without hesitation and keep it on the shelf as the working atlas. Engage with it; cite the assignments when you need them.","headline":"Solid termination-resolved ARPES+DFT atlas that finally sorts bulk from surface on both PtBi2(0001) faces; useful infrastructure, not a mechanism paper.","tokens_in":13948,"tokens_out":471,"would_cite":true,"duration_ms":15842,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.5","headline":"Photon-energy and polarization ARPES separate bulk bands from surface states on both terminations of PtBi2(0001).","keywords":["PtBi2","ARPES","surface states","bulk bands","Fermi arcs","Weyl semimetal","orbital character","surface termination"],"falsifier":"A soft-X-ray or broader photon-energy ARPES series in which any of the assigned surface features (the Fermi arc, the DH Γ Dirac-like crossing, or the steep near-EF KL band labeled mixed) clearly disperses with kz, or a slab calculation that moves that DH crossing into agreement with experiment while destroying the other surface assignments.","tokens_in":13973,"feed_emoji":"🔬","tokens_out":878,"duration_ms":25728,"temperature":0.7,"pith_summary":"Reports of surface-localized topological superconductivity in trigonal PtBi2 make its surface electronic structure a practical problem, not just a band-structure curiosity. This paper uses vacuum-ultraviolet ARPES while sweeping photon energy and light polarization, together with density-functional surface calculations, to pull bulk dispersions apart from surface states on the two distinct cleave terminations (decorated-honeycomb and Kagome-like). Several surface features—including the Fermi arc and, on the decorated-honeycomb face, a Dirac-like crossing at the zone center—are assigned and matched to calculation. Orbital weights from the same calculations line up with the polarization dependence seen in the spectra. The result is a termination-resolved map of which states are bulk, which are surface, and how they hybridize near the Fermi level.","feed_headline":"ARPES splits bulk from surface bands on both PtBi2 faces","feed_subtitle":"Photon energy and polarization map which states are surface—key for claimed topological surface superconductivity.","key_machinery":"Photon-energy series plus polarization matrix-element contrast in ARPES, read against DFT surface spectral weight on semi-infinite Wannier slabs for the two terminations—the tool that labels which intensity is bulk (kz-dispersive continuum) versus surface (sharp, kz-independent).","core_discovery":"By combining photon-energy-dependent ARPES (to track kz bulk dispersion) with polarization-dependent intensity and semi-infinite slab spectral-weight calculations, the bulk continuum can be disentangled from true surface states on both DH and KL terminations of PtBi2(0001). Several surface features are assigned on each face, experiment and calculation agree well enough to give a coherent picture, and the orbital makeup of those bands explains the observed polarization contrast.","pith_inferences":["Any claim that the superconducting gap lives only on Fermi arcs needs termination-controlled samples; mixed bulk–surface weight on KL could dilute or mimic a surface gap.","The ~0.2 eV theory–experiment offset of the DH Dirac crossing is a natural target for beyond-GGA or surface-relaxation calculations before using that state as a topological marker.","Spin-resolved ARPES on the polarization-selected DH pz-dominated crossing would test whether that state carries a distinct spin texture from the arc."],"forward_implications":["Termination must be specified when linking ARPES or STM gaps to topological surface superconductivity on PtBi2.","The DH Dirac-like crossing and the KL Fermi-arc mixing with bulk continuum are distinct spectroscopic fingerprints of each face.","Polarization can be used as an orbital filter to enhance or suppress specific surface bands in future gap or spin measurements.","Bulk Rashba-like branches and steep A-plane bands are now experimentally anchored against calculation across a wide photon-energy range."],"fun_headline_variants":["ARPES untangles bulk continuum from surface states on both PtBi2 faces","Photon energy and polarization assign surface bands on DH and KL PtBi2","Bulk vs surface states separated on both PtBi2(0001) terminations","Calculations and ARPES map orbital makeup of PtBi2 surface bands","Coherent surface electronic structure of PtBi2 across both faces"],"cache_read_input_tokens":128,"weakest_assumption_plain":"That VUV photon energies, with their finite escape-depth kz broadening, plus standard GGA slab calculations, are accurate enough to uniquely tag mixed bulk–surface bands even when theory and experiment sit a few tenths of an eV apart.","fun_headline_variants_meta":{"raw":{"variants":["ARPES untangles bulk continuum from surface states on both PtBi2 faces","Photon energy and polarization assign surface bands on DH and KL PtBi2","Bulk vs surface states separated on both PtBi2(0001) terminations","Calculations and ARPES map orbital makeup of PtBi2 surface bands","Coherent surface electronic structure of PtBi2 across both faces"]},"model":"grok-4.5","effort":"low","cost_usd":0.004654,"raw_usage":{"total_tokens":1286,"prompt_tokens":711,"num_sources_used":0,"completion_tokens":80,"cost_in_usd_ticks":46544000,"prompt_tokens_details":{"text_tokens":711,"audio_tokens":0,"image_tokens":0,"cached_tokens":128},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":495,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":711,"tokens_out":80,"duration_ms":7894,"temperature":1.0,"reasoning_tokens":495,"cache_read_input_tokens":128,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-07-30T20:33:23.059101+00:00","model_set":{"reader":"grok-4.5"},"falsifier":"A soft-X-ray or broader photon-energy ARPES series in which any of the assigned surface features (the Fermi arc, the DH Γ Dirac-like crossing, or the steep near-EF KL band labeled mixed) clearly disperses with kz, or a slab calculation that moves that DH crossing into agreement with experiment while destroying the other surface assignments.","supporting_citations":[],"review_version":1}