Phonon density of states and the search for a resonance mode in LaFeAsO<sub>0.85</sub>F<sub>0.15</sub>(T<sub><i>c</i></sub>= 26 K)
Bibliographic record
Abstract
While the high transition temperatures suggest that the conventional BCS phononmediated \nmechanism may not provide the main pairing mechanism in the recently discovered RFeAsO1−xFx (1111- \ntype) superconductors, there is, as yet, no consensus, despite extensive experimental and theoretical study. \nWe report here the results of an inelastic neutron scattering investigation of an overdoped polycrystalline \nsample of LaFeAsO1−xFx with x=0.15 (Tc=26 K). Four excitation peaks were observed at 13.6±1.5, \n24.2±0.8, 32.2±0.5, and 41.4±1.0 meV. They were identified as phonon modes based on their wavevector and \ntemperature dependence. The peak positions agree well with first-principles calculations of phonon density \nof states as well as experimental data on both the insulating parent and optimally doped LaFeAsO1−xFx \ncompounds. No evidence for the presence of a resonance mode was found. We found that the phonon density \nof states of the x=0.15 sample remains unchanged below Tc and is similar to samples with other fluorine \nconcentrations. This suggests that a standard electron-phonon pairing mechanism cannot explain the high \ntransition temperatures observed in these materials.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.002 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".