Spin-state ordering and intermediate states in the mixed-valence cobalt oxyborate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Co</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>BO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math> with spin crossover
Bibliographic record
Abstract
Spin-state ordering---a periodic pattern of ions with different spin-state configurations along a crystal lattice---is a rare phenomenon, and its possible interrelation with other electronic degrees of freedom remains little explored. Here we perform a structural investigation of the mixed-valence Co homometallic ludwigite ${\mathrm{Co}}_{2}^{2+}{\mathrm{Co}}^{3+}{\mathrm{O}}_{2}{\mathrm{BO}}_{3}$. A superstructure consistent with a long-range ${\mathrm{Co}}^{3+}$ spin-state ordering is observed between ${T}_{4}=580$ K and ${T}_{3}=510$ K. Intermediate states with mesoscopic correlations are detected below ${T}_{3}$ down to ${T}_{1}=480$ K with a change of dimensionality at ${T}_{2}=495$ K. The spin-state correlations are connected to the charge sector as revealed by the abrupt changes in the electrical resistance at ${T}_{1}$ and ${T}_{2}$. The evolution of the structural parameters below ${T}_{1}$ indicate that the spin crossover is ignited by a moderate degree of thermally induced ${\mathrm{Co}}^{2+}$ and ${\mathrm{Co}}^{3+}$ charge disorder. Charge and spin-state degrees of freedom can be interrelated in mixed-valence spin-crossover materials, leading to sharp transitions involving intermediate spin-state and charge-correlated states at the mesoscale.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".