Raman study of twin-free ortho-II<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>YBa</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mtext>Cu</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mrow><mml:mn>6.5</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>single crystals
Bibliographic record
Abstract
The polarized Raman scattering spectra from freshly cleaved $ab$, $ac$, and $bc$ surfaces of high quality twin-free ${\text{YBa}}_{2}{\text{Cu}}_{3}{\text{O}}_{6.5}$ (ortho-II) single crystals (${T}_{c}=57.5\text{ }\text{K}$ and $\ensuremath{\Delta}T=0.6\text{ }\text{K}$) were studied between 80 and 300 K. All 11 ${A}_{g}$ Raman modes expected for the ortho-II structure as well as some modes of ${B}_{2g}$ and ${B}_{3g}$ symmetries were identified in close comparison to predictions of lattice dynamical calculations. The electronic scattering from the $ab$ planes is strongly anisotropic and decreases between 200 and 100 K within the temperature range of a previously reported pseudogap opening. The coupling of phonons to Raman active electronic excitations manifested by asymmetric (Fano) profiles of several modes also decreases within the same range. Among the findings that distinguish the Raman scattering of the ortho-II phase from that of the ortho-I phase is the unusual relationship $({\ensuremath{\alpha}}_{xx}\ensuremath{\approx}\ensuremath{-}{\ensuremath{\alpha}}_{yy})$ between the elements of the Raman tensor of the apex oxygen ${A}_{g}$ mode.
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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) | 0.002 | 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".