Detection of phonon helicity in nonchiral crystals with Raman scattering
Bibliographic record
Abstract
Recently, it has been predicted that the Berry curvature of electrons can produce an angular momentum for phonons. In systems with time-reversal symmetry, the direction of the phonon angular momentum is locked to the phonon wave vector. Accordingly, this phenomenon has received the name of ``phonon helicity.'' Here, we present a theory to unveil the signatures of such phonon helicity using Raman scattering. We show that the intensity of Raman scattering for circularly polarized light in ${\mathrm{BaMnSb}}_{2}$ (a prototypical nonchiral Dirac insulator) changes under a reversal of the phonon wave vector, and that the phonon helicity can be inferred from that change. We compare our results to recent reports of Raman-based detection of phonon angular momentum in chiral crystals.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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 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".