Microwave spectroscopy of vortex dynamics in ortho-II YBa<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow/><mml:mn>2</mml:mn></mml:msub></mml:math>Cu<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow/><mml:mn>3</mml:mn></mml:msub></mml:math>O<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow/><mml:mrow><mml:mn>6.52</mml:mn></mml:mrow></mml:msub></mml:math>
Bibliographic record
Abstract
We present measurements of the vortex-state surface impedance, ${Z}_{s}={R}_{s}+\mathrm{i}{X}_{s}$, of a high-quality, ortho-II-ordered single crystal of the cuprate high-temperature superconductor YBa${}_{2}$Cu${}_{3}$O${}_{6.52}$ (${T}_{c}=59$ K). Measurements have been made at four microwave frequencies ($\ensuremath{\omega}/2\ensuremath{\pi}=2.64$, 4.51, 9.12, and 13.97 GHz) for magnetic fields ranging from 0 to 7 T. From these data we obtain the field, frequency, and temperature dependence of the vortex viscosity, pinning constant, depinning frequency, and flux-flow resistivity. The vortex viscosity, $\ensuremath{\eta}(\ensuremath{\omega},T)$, has a surprisingly strong frequency dependence and bears a striking resemblance to the zero-field quasiparticle conductivity, ${\ensuremath{\sigma}}_{\mathrm{qp}}(\ensuremath{\omega},T)$, suggesting that the dominant dissipative mechanism for the flux lines is induced electric fields coupling to bulk, long-lived $d$-wave quasiparticles outside the vortex cores. This is in sharp contrast to the conventional Bardeen-Stephen picture, in which dissipation takes place inside quasinormal vortex cores. The strong frequency dependence of the vortex viscosity in the microwave range requires us to treat it as a complex response function, with an imaginary part that is predicted to contribute to the apparent pinning force on the vortices. Measurements of the frequency dependence of the pinning force confirm that this term is present, and in a form consistent with the requirements of causality. At low temperatures the flux-flow resistivity, ${\ensuremath{\rho}}_{\mathrm{ff}}\ensuremath{\propto}1/\ensuremath{\eta}$, has the form ${\ensuremath{\rho}}_{\mathrm{ff}}(T)={\ensuremath{\rho}}_{0}+{\ensuremath{\rho}}_{1}\mathrm{ln}(1/T)$, reminiscent of the dc resistivity of cuprates in the pseudogap regime.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".