Spin singlet and quasiparticle excitations in cuprate superconductors
Bibliographic record
Abstract
We followed step by step the transition from an antiferromagnetic (AFM) Mott insulator to a superconducting (SC) metal in the ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ (Bi-2212) cuprate using electronic Raman scattering spectroscopy. This was achieved by tracking the doping dependence of the spin singlet excitation (SSE) originating from the AFM Mott insulator, the normal-state quasiparticle excitation related to the mobile charge carriers, and the Bogoliubov quasiparticles related to the SC gap. We show that the signature of the pseudogap phase which develops during this transition can be interpreted as the blocking of charge carriers by the enhancement of the AFM correlations as the temperature drops. We find that the energy scale of the pseudogap, ${\mathrm{\ensuremath{\Delta}}}_{\text{pg}}(p)$, closely follows that of the SSE, ${\mathrm{\ensuremath{\Delta}}}_{\text{sse}}(p)$ with doping $p$. The quasiparticle lifetime considerably increases with doping when the pseudogap collapses. We reveal that the maximum amplitude of the SC gap ${\mathrm{\ensuremath{\Delta}}}_{\text{sc}}^{\text{max}}$ and the SC transition temperature ${T}_{\mathrm{c}}$ are linked in an extended range of doping, such as ${\mathrm{\ensuremath{\Delta}}}_{\text{sc}}^{\text{max}}(p)\ensuremath{\propto}{\mathrm{\ensuremath{\Delta}}}_{\text{sse}}(p)\phantom{\rule{0.16em}{0ex}}{T}_{\mathrm{c}}\phantom{\rule{0.16em}{0ex}}(p)$. This relation suggests that the AFM correlations play a key role in the mechanism of 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) | 0.001 | 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".