Detection of a Fermi-level crossing in Si(557)-Au with inverse photoemission
Bibliographic record
Abstract
The unoccupied energy bands of the quasi-one-dimensional (1D) Si(557)-Au system have been studied with momentum-resolved inverse photoemission. A band is found that lies $(0.4\ifmmode\pm\else\textpm\fi{}0.4)\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ above the Fermi level at the center of the surface Brillouin zone $(\overline{\ensuremath{\Gamma}})$. It disperses to higher binding energy, along the $\overline{\ensuremath{\Gamma}K}$ direction, and crosses the Fermi level at ${k}_{\ensuremath{\Vert}}=0.5\ifmmode\pm\else\textpm\fi{}0.1\phantom{\rule{0.3em}{0ex}}{\mathrm{\AA{}}}^{\ensuremath{-}1}$. The corresponding direction in real space is parallel to both the rows of silicon adatoms and the rows of embedded gold atoms that are distinctive features of this surface reconstruction. The location of the crossing is in good agreement with previously published photoemission data [Altmann et al., Phys. Rev. B 64, 035406 (2001); Ahn et al., Phys. Rev. Lett. 91, 196403 (2003)], where two closely spaced bands were found to disperse from the $\overline{K}$ zone boundary to lower binding energy and then cross the Fermi level. In addition to the band mentioned above, a band was found that has parabolic dispersion along $\overline{\ensuremath{\Gamma}K}$, the direction that is parallel to the rows of embedded gold atoms. The band minimum for the parabolic band lies $(0.8\ifmmode\pm\else\textpm\fi{}0.4)\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ below the vacuum level and it has an effective mass ${m}^{*}=(1.0\ifmmode\pm\else\textpm\fi{}0.1){m}_{e}$, where ${m}_{e}$ is the free electron mass. Perpendicular to the rows of gold atoms, as expected for a state with quasi-1D symmetry, it has flat dispersion. This band may be an image state resonance, overlapping the silicon conduction band continuum, and it is spatially localized to the edge of the silicon terraces.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".