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 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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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 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".