Ultrafast Umklapp-assisted electron-phonon cooling in magic-angle twisted bilayer graphene.

ABSTRACT: Understanding electron-phonon interactions is fundamentally important and has crucial implications for device applications. However, in twisted bilayer graphene near the magic angle, this understanding is currently lacking. Here, we study electron-phonon coupling using time- and frequency-resolved photovoltage measurements as direct and complementary probes of phonon-mediated hot-electron cooling. We find a remarkable speedup in cooling of twisted bilayer graphene near the magic angle: The cooling time is a few picoseconds from room temperature down to 5 kelvin, whereas in pristine bilayer graphene, cooling to phonons becomes much slower for lower temperatures. Our experimental and theoretical analysis indicates that this ultrafast cooling is a combined effect of superlattice formation wit

SUBMITTER: Mehew JD 

PROVIDER: S-EPMC10857426 | biostudies-literature | 2024 Feb

REPOSITORIES: biostudies-literature