Plasmon dispersion in bilayer cuprate superconductors
Bibliographic record
Abstract
The essential building blocks of cuprate superconductors are two-dimensional <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>CuO</a:mi><a:mn>2</a:mn></a:msub></a:math> sheets interspersed with charge reservoir layers. In bilayer cuprates, two closely spaced <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>CuO</b:mi><b:mn>2</b:mn></b:msub></b:math> sheets are separated by a larger distance from the subsequent pair in the next unit cell. In contrast to single-layer cuprates, prior theoretical work on bilayer systems has predicted two distinct acoustic plasmon bands for a given out-of-plane momentum transfer. Here we report random phase approximation (RPA) calculations for bilayer systems which corroborate the existence of two distinct plasmon bands. We find that the intensity of the lower-energy band is negligibly small in most parts of the Brillouin zone, whereas the higher-energy band carries significant spectral weight. We also present resonant inelastic x-ray scattering (RIXS) experiments at the O <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mi>K</c:mi></c:math>-edge on the bilayer cuprate <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mrow><d:msub><d:mi mathvariant="normal">Y</d:mi><d:mrow><d:mn>0.85</d:mn></d:mrow></d:msub><d:msub><d:mi>Ca</d:mi><d:mrow><d:mn>0.15</d:mn></d:mrow></d:msub><d:msub><d:mi>Ba</d:mi><d:mn>2</d:mn></d:msub><d:msub><d:mi>Cu</d:mi><d:mn>3</d:mn></d:msub><d:msub><d:mi mathvariant="normal">O</d:mi><d:mn>7</d:mn></d:msub></d:mrow></d:math> (Ca-YBCO), which show only one dispersive plasmon branch, in agreement with the RPA calculations. In addition, the RPA results indicate that the dispersion of the higher-energy plasmon band in Ca-YBCO is not strictly acoustic but exhibits a substantial energy gap of approximately 250 meV at the two-dimensional Brillouin zone center. Published by the American Physical Society 2024
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.003 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.003 |
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 teacher head, 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".