Intermediate temperature structural modulation and properties of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>CoIn</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>
Bibliographic record
Abstract
At temperature $T=293\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, the crystal structure of ${\mathrm{CoIn}}_{2}$ is characterized by linear chains of equidistant Co atoms, but these chains undergo pairwise dislocation via Peierls distortion at some $T>90\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ [Z. Kristallogr. 237, 239 (2022)]. Recently published differential scanning calorimetry measurements revealed at least two intervening thermodynamic effects near ${T}_{1}=194(1)\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and ${T}_{2}=206(2)\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ but did not clarify how these features were related to the structural distortion or distortions. In the present paper, we report a suite of measurements on high-quality single crystals of ${\mathrm{CoIn}}_{2}$. We observe clear signatures of both transitions in $T$-dependent measurements of heat capacity, electrical resistivity, and dc magnetization. Moreover, we find a new crystal structure with polar orthorhombic space group $Fdd2$ to reside between the two transitions at $T=198(2)\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. Like the high-$T$ structure, the lattice of this intermediate-$T$ structure remains characterized by a single intrachain Co-Co distance ${d}_{\mathrm{Co}\ensuremath{-}\mathrm{Co}}=2.69324(10)\phantom{\rule{0.16em}{0ex}}\AA{}$, but sparse $\mathcal{O}(1%)$ structural disorder is resolved by the formation of a structural modulation with propagation vector $\mathbf{q}=(0,\ensuremath{\delta},0), \ensuremath{\delta}=0.23\ifmmode\pm\else\textpm\fi{}0.02$ oriented in a direction perpendicular to the Co-Co chains. We discuss the results in light of the potential onset of a charge density wave state above the Peierls distortion.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".