Characterization of the 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>linear-chain ferromagnet CuAs<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow/><mml:mn>2</mml:mn></mml:msub></mml:math>O<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow/><mml:mn>4</mml:mn></mml:msub></mml:math>
Bibliographic record
Abstract
The magnetic and lattice properties of the $S=1/2$ quantum-spin-chain ferromagnet CuAs${}_{2}$O${}_{4}$, mineral name trippkeite, were investigated. The crystal structure of CuAs${}_{2}$O${}_{4}$ is characterized by the presence of corrugated CuO${}_{2}$ ribbon chains. Measurements of the magnetic susceptibility, heat capacity, electron paramagnetic resonance, and Raman spectroscopy were performed. Our experiments conclusively show that a ferromagnetic transition occurs at $\ensuremath{\sim}$7.4 K. Ab initio DFT calculations reveal dominant ferromagnetic nearest-neighbor and weaker antiferromagnetic next-nearest-neighbor spin exchange interactions along the ribbon chains. The ratio of ${J}_{\mathrm{nn}}$/${J}_{\mathrm{nnn}}$ is near $\ensuremath{-}$4, placing CuAs${}_{2}$O${}_{4}$ in close proximity to a quantum critical point in the ${J}_{\mathrm{nn}}$-${J}_{\mathrm{nnn}}$ phase diagram. TMRG simulations used to analyze the magnetic susceptibility confirm this ratio. Single-crystal magnetization measurements indicate that a magnetic anisotropy forces the Cu${}^{2+}$ spins to lie in an easy plane perpendicular to the $c$ axis. An analysis of the field- and temperature-dependent magnetization by modified Arrott plots reveals a 3d-$X$Y critical behavior. Lattice perturbations induced by quasihydrostatic pressure and temperature were mapped via magnetization and Raman spectroscopy.
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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 | 0.006 | 0.003 |
| Meta-epidemiology (narrow) | 0.005 | 0.007 |
| Meta-epidemiology (broad) | 0.003 | 0.008 |
| Bibliometrics | 0.001 | 0.004 |
| Science and technology studies | 0.005 | 0.005 |
| Scholarly communication | 0.004 | 0.006 |
| Open science | 0.008 | 0.008 |
| Research integrity | 0.005 | 0.007 |
| Insufficient payload (model declined to judge) | 0.025 | 0.015 |
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".