Collapse of the magnetization by the application of crossed magnetic fields: observations in a commercial Bi:2223/Ag tape and comparison with numerical computations
Bibliographic record
Abstract
We report on the effects of crossed magnetic fields on a commercial Bi:2223/Ag tape superconductor. The large magnetic moments which are generated in the specimen by the application or change of an external magnetic field (denoted H z ) directed perpendicularly to the plane of the tapes, hence along the c -axis of the crystallites, are considerably reduced in magnitude when subsequently a magnetic field (denoted H y ) directed along the plane of the tape, hence along the ab plane of the crystallites, is impressed and removed and made to undergo several half cycles of oscillations in the opposite direction. We find that a few cycles cause the magnetic moment to rapidly depart from the critical state major hysteresis envelope and reach asymptotically the reversible diamagnetic Meissner moment M rev , which is aligned in the out-of-plane direction of the tape ( c -axis). We observe that the application of crossed fields, first along the c -axis, then along the ab plane, effectively suppresses the bulk pinning magnetic moment, and quenches the associated persistent currents circulating in the ab plane. Our numerical computations, based on the finite element method and using an E – J power law to model the superconductor, can reproduce qualitatively the experimental data. In the numerical model, the current density flows perpendicularly to the plane within which the two components of the magnetic field vary. These investigations show that the observed decay in magnetization results from the complicated modification of current distribution due to the application of crossed magnetic fields within the sample cross section.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".