Photoinduced phase heterogeneity and charge localization in SnSe
Bibliographic record
Abstract
Time-resolved multi-terahertz (THz) spectroscopy is used to observe pump fluence-dependent dynamics in the optical conductivity of photoexcited tin selenide (SnSe) over an ultrabroadband spectral range of 0.5 - 11 THz at fluences from 0.1 - 7.5 mJ/cm$^2$. A free carrier Drude spectrum is observed at pump fluences below 3 mJ/cm$^2$, with optical phonons well described by the equilibrium Pnma structural phase. With increasing fluence, a suppression of the DC photoconductivity is observed, indicating an interruption of long range transport due to phase disorder. Concomitantly, the optical phonons exhibit features that can no longer be explained by a pure Pnma phase, with a frequency shift and narrowing of the $B^2_{1u}$ mode and a new mode appearing at $\sim$3.0 THz consistent with a transition to a higher-symmetry structure. At an intermediate fluence of 3.1 mJ/cm$^2$, a high frequency Lorentzian component consistent with phase heterogeneity appears that rapidly redshifts after 2 ps and whose amplitude exponentially decays on a 90 ps time scale. Our experimental measurements and theoretical calculations provide evidence for a non-thermal, photo-induced nucleation of higher symmetry, semi-metallic phase domains in SnSe appearing within 200 fs.
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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".