Spin-orbit interaction enabled electronic Raman scattering from charge collective modes
Bibliographic record
Abstract
Electronic Raman scattering in the fully symmetric channel couples to the charge excitations in the system, including the plasmons. However, the plasmon response has a spectral weight of $\sim q^2$, where $q$, the momentum transferred by light, is small. In this work, we show that in inversion symmetry broken systems where Rashba type spin-orbit coupling affects the states at the Fermi energy (which is a known low energy effect) as well as the transition elements to other states (a high energy effect), there is an additional coupling of the plasmons to the Raman vertex, even at zero momentum transfer, that results in a spectral weight that is proportional to the spin-orbit coupling. The high energy effect is due to the breaking of SU(2) spin invariance in the spin-flip transitions to the intermediate state. We present a theory for this coupling near the resonant regime of Raman scattering and show that in giant Rashba systems it can dominate over the conventional $q^2$ weighted coupling. We also provide experimental support along with a symmetry based justification for this spin-mediated coupling by identifying a prominent c-axis plasmon peak in the fully symmetric channel of the resonant Raman spectrum of the giant Rashba material BiTeI. This new coupling could lead to novel ways of manipulating coherent charge excitations in inversion-broken systems. This process is also relevant for spectroscopic studies in ultrafast spectroscopies, certain driven Floquet systems and topologically non-trivial phases of matter where strong inversion-breaking spin-orbit coupling plays a role.
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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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".