Perpendicular Andreev reflection: Solid-state signature of black-hole horizon
Bibliographic record
Abstract
Beenakker noticed that the peculiar band structure of Dirac fermions in two-dimensional (2D) solids allows for the specular Andreev reflection in these systems, which has no analogue in other 2D electron systems. An interesting deformation of the Dirac equation in the solid state is to tilt it, which has now been realized in materials. In this paper we report another peculiar feature of the Andreev reflection in tilted 2D Dirac cone systems. The tilt deformation of the Dirac equation is characterized by two parameters $\mathbit{\ensuremath{\zeta}}=\ensuremath{\zeta}(cos\ensuremath{\theta},sin\ensuremath{\theta})$. We show that when the tilt parameter is tuned to its ``horizon value'' $\ensuremath{\zeta}=1$, irrespective of the incidence angle of electrons, the Andreev reflected hole is always reflected perpendicular to the interface. Furthermore, at $\ensuremath{\zeta}=1$, if the tilt direction is perpendicular to the interface, the conductance will be energy independent for all subgap energies. For generic tilt $\mathbit{\ensuremath{\zeta}}$, the tilt dependence of the conductance line shape can be used to extract information about the direction and magnitude of the tilt.
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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 | 0.001 |
| 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 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".