ARPES Signatures of Few-Layer Twistronic Graphenes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 37235208.
- Also identified by DOI 10.1021/acs.nanolett.3c01173 and PMC identifier 10273478.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Diverse emergent correlated electron phenomena have been observed in twisted-graphene layers. Many electronic structure predictions have been reported exploring this new field, but with few momentum-resolved electronic structure measurements to test them. We use angle-resolved photoemission spectroscopy to study the twist-dependent (1° < θ < 8°) band structure of twisted-bilayer, monolayer-on-bilayer, and double-bilayer graphene (tDBG). Direct comparison is made between experiment and theory, using a hybrid <b>k</b>·<b>p</b> model for interlayer coupling. Quantitative agreement is found across twist angles, stacking geometries, and back-gate voltages, validating the models and revealing field-induced gaps in twisted graphenes. However, for tDBG at θ = 1.5 ± 0.2°, close to the magic angle θ = 1.3°, a flat band is found near the Fermi level with measured bandwidth <i>E</i><sub>w</sub> = 31 ± 5 meV. An analysis of the gap between the flat band and the next valence band shows deviations between experiment (Δ<sub>h</sub> = 46 ± 5 meV) and theory (Δ<sub>h</sub> = 5 meV), indicative of lattice relaxation in this regime.