Pressure evolution of the normal- and superconducting-state properties of the line-nodal material <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>CaSb</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> revealed by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Sb</mml:mi><mml:mprescripts/><mml:none/><mml:mn>123</mml:mn></mml:mmultiscripts></mml:math> nuclear quadrupole resonance
Bibliographic record
Abstract
${\mathrm{CaSb}}_{2}$ is the Dirac line-nodal material that exhibits a superconducting (SC) transition at 1.7 K. In spite of its conventional SC state at ambient pressure, the transition temperature ${T}_{\mathrm{c}}$ shows a peak structure against hydrostatic pressure. We performed ac magnetic susceptibility and $^{123}\mathrm{Sb}$ nuclear quadrupole resonance (NQR) measurements on single-crystalline ${\mathrm{CaSb}}_{2}$ under pressures up to 2.08 GPa. ${T}_{\mathrm{c}}$ monotonically increased in this pressure region, which is consistent with a previous study. We observed continuous broadening of the NQR spectrum against pressure, which is a sign of unique compression behavior of the lattice. In the normal state, the nuclear spin-lattice relaxation rate $1/{T}_{1}$ is proportional to temperature in all pressure values, typical of a metal. However, $1/{T}_{1}T$ in the normal state is independent of pressure, indicating that the density of states at the Fermi energy $N({E}_{\mathrm{F}})$, which is one of the parameters governing ${T}_{\mathrm{c}}$, is insensitive to pressure. From these results, we conclude that $N({E}_{\mathrm{F}})$ does not govern the origin of the enhancement in ${T}_{\mathrm{c}}$. This is unusual for a weak electron-phonon coupling superconductor. In the SC state, we revealed that the SC gap becomes larger and more isotropic under pressure.
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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 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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".