Determining Electron Spin-Transfer Mechanisms in Paramagnetic Ba<sub>2</sub>YMO<sub>6</sub> (M = Mo, Re, Ru) Double Perovskites by <sup>89</sup>Y and <sup>137</sup>Ba MAS NMR Spectroscopy
Bibliographic record
Abstract
The spin-transfer mechanisms of three B-site ordered double perovskites, Ba 2 YMO 6 (M = Mo, Re, and Ru), were determined using variable-temperature 89 Y and 137 Ba magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. On the basis of symmetry-compatible overlap and trends observed in the MAS NMR, spin polarization was determined to be the dominant mechanism at the Y sites and spin delocalization to be the operative mechanism at the Ba sites. The MAS NMR spectra display 89 Y and 137 Ba chemical shifts that far exceed those of other paramagnetic solids, appearing at up to −6402 and +12 200 ppm, respectively. Detection of additional resonances in 89 Y MAS NMR indicates a small degree of cation site mixing in two cases.
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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".