Optical properties and Landau quantisations in twisted bilayer graphene

ABSTRACT

The optical properties and Landau quantisations in twisted bilayer graphene are investigated using a generalised tight-binding model that takes into account all interlayer and intralayer atomic interactions in the Moire superlattice. The system is a zero-gap semiconductor with double-degenerate Dirac-cone structures, and saddle-point energy dispersions appear at low energies for small twisting angles. The magnetic quantisation phenomena in this system are rich and unique, with Landau-level subgroups specified owing to specific Moire zone folding through modulation of the stacking angles. The Landau-level spectrum shows hybridised characteristics associated with those in monolayer, as well as AA and AB stackings. The detailed analysis explores the complex relations among the different sublattices on the same and different graphene layers.

KEYWORDS:

• Twisted bilayer graphene
• Moiré superlattice
• Landau levels
• optical properties
• tight-binding model

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported in part by the National Science and Technology Council, the Republic of China, under Grant Nos. NSC 99-2112-M-165-001-MY3 and MOST 109-2811-M-006-531.