Optical activity and transport in twisted bilayer graphene: the essence of spatial dispersion effects

Abstract

This study investigates optical activity and quantum transport in twisted bilayer graphene (TBG) systems, demonstrating that the former results from spatial dispersion effects. The transfer matrix method is used to solve the propagation of electromagnetic waves through two graphene layers that act as the coupling surfaces of a dielectric slab. The resulting optical conductivity tensor is decomposed into a local and a drag part, with the drag transverse conductivity ${\sigma }_{xy}^{(drag)}$ governing the TBG system's optical property. An effective continuum model is employed to analyze electron state formation and calculate relevant parts of the optical conductivity tensor. Correlation of electron motions leads to incomplete cancellation and a finite ${\sigma }_{xy}^{(drag)}$ in the chiral TBG lattice. The study also calculates DC conductivity, showing TBG supports quantum conductivity proportional to $e^2/h$ at the intrinsic Fermi energy.

arXiv admin note: substantial text overlap with arXiv:2205.12675

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Cited by in corpus (6)

• Terahertz Circular Dichroism in Commensurate Twisted Bilayer Graphene
• Layer Hall counterflow as a model probe of magic-angle twisted bilayer graphene
• Moiré semiconductors on twisted bilayer dice lattice
• Unique properties of the optical activity in noncentrosymmetric superconductors: sum rule, missing area, and relation with the superconducting Edelstein effect
• Review of the tight-binding method applicable to the properties of moiré superlattices
• Orbital optical activity in noncentrosymmetric metals and superconductors