Deformation of the triangular spin-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mfrac><mml:mn>1</mml:mn><mml:mn>2</mml:mn></mml:mfrac></mml:math> lattice in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Na</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mi>SrCo</mml:mi><mml:mo>(</mml:mo><mml:mi>PO</mml:mi></mml:mrow><mml:mn>4</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mo>)</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>
Bibliographic record
Abstract
Crystal structure and thermodynamic properties of ${\mathrm{Na}}_{2}\mathrm{SrCo}{({\mathrm{PO}}_{4})}_{2}$, the chemical sibling of the triangular quantum spin-liquid candidate ${\mathrm{Na}}_{2}\mathrm{BaCo}{({\mathrm{PO}}_{4})}_{2}$, are reported. From single crystal x-ray diffraction and high-resolution synchrotron x-ray powder diffraction, the compound was found to crystallize in the monoclinic space group $P{2}_{1}/a$ at room temperature, in contrast to the trigonal ${\mathrm{Na}}_{2}\mathrm{BaCo}{({\mathrm{PO}}_{4})}_{2}$. Above 650 K, the symmetry of ${\mathrm{Na}}_{2}\mathrm{SrCo}{({\mathrm{PO}}_{4})}_{2}$ changes to $C2/m$, while around 1025 K a further transformation toward trigonal symmetry is observed. The monoclinic symmetry leads to a small deformation of the ${\mathrm{CoO}}_{6}$ octahedra beyond the trigonal distortion ubiquitous in this structure type and results in the stronger $g$-tensor anisotropy (${g}_{\text{z}}/{g}_{\text{xy}}=1.6$) as well as the increased XXZ anisotropy (${J}_{\text{z}}/{J}_{\text{xy}}=2.1$) compared to the Ba compound (${g}_{\text{z}}/{g}_{\text{xy}}=1.1, {J}_{\text{z}}/{J}_{\text{xy}}=1.5$), while the average coupling strength, ${J}_{\text{av}}/{k}_{\text{B}}=(2{J}_{\text{xy}}+{J}_{\text{z}})/3{k}_{\text{B}}\ensuremath{\simeq}1.3\phantom{\rule{4pt}{0ex}}\text{K}$, remains unchanged. The N\'eel temperature increases from 140 mK (Ba) to 600 mK (Sr), and an uncompensated in-plane moment of $0.066(4){\ensuremath{\mu}}_{\text{B}}/\text{f.u.}$ appears. We show that the ordering temperature of a triangular antiferromagnet is capably controlled by its structural distortions.
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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 | 0.008 | 0.006 |
| Meta-epidemiology (narrow) | 0.005 | 0.009 |
| Meta-epidemiology (broad) | 0.002 | 0.012 |
| Bibliometrics | 0.002 | 0.008 |
| Science and technology studies | 0.007 | 0.007 |
| Scholarly communication | 0.005 | 0.007 |
| Open science | 0.011 | 0.011 |
| Research integrity | 0.006 | 0.010 |
| Insufficient payload (model declined to judge) | 0.504 | 0.011 |
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; both teacher heads agree on what is shown here.
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".