Penetration depth and gap structure in the antiperovskite oxide superconductor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>Sr</mml:mi><mml:mrow><mml:mn>3</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mi>SnO</mml:mi></mml:math> revealed by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>μ</mml:mi><mml:mi>SR</mml:mi></mml:math>
Bibliographic record
Abstract
We report a $\ensuremath{\mu}\mathrm{SR}$ study on the antiperovskite oxide superconductor ${\mathrm{Sr}}_{3\ensuremath{-}x}\mathrm{SnO}$. By using transverse-field $\ensuremath{\mu}\mathrm{SR}$, we observed an increase of the muon relaxation rate upon cooling below the superconducting transition temperature ${T}_{\mathrm{c}}=5.4$ K, evidencing bulk superconductivity. The exponential temperature dependence of the relaxation rate $\ensuremath{\sigma}$ at low temperatures suggests a fully gapped superconducting state. We evaluated the zero-temperature penetration depth $\ensuremath{\lambda}(0)\ensuremath{\propto}1/\sqrt{\ensuremath{\sigma}(0)}$ to be around 320--1020 nm. Such a large value is consistent with the picture of a doped Dirac semimetal. Moreover, we established that the ratio ${T}_{\mathrm{c}}/\ensuremath{\lambda}{(0)}^{\ensuremath{-}2}$ is larger than those of ordinary superconductors and is comparable to those of unconventional superconductors. The relatively high ${T}_{\mathrm{c}}$ for small carrier density may hint at an unconventional pairing mechanism beyond the ordinary phonon-mediated pairing. In addition, zero-field $\ensuremath{\mu}\mathrm{SR}$ did not provide evidence of broken time-reversal symmetry in the superconducting state. These features are consistent with the theoretically proposed topological superconducting state in ${\mathrm{Sr}}_{3\ensuremath{-}x}\mathrm{SnO}$, as well as with ordinary $s$-wave superconductivity.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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 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".