Theory of Optical Activity in Doped Systems with Application to Twisted Bilayer Graphene

We theoretically study the optical activity in a doped system and derive the optical activity tensor from a light wavevector-dependent linear optical conductivity. Although the light-matter interaction is introduced through the velocity gauge from a minimal coupling Hamiltonian, we find that the wel...

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Bibliographic Details
Published in:arXiv.org 2022-10
Main Authors: Chang, K, Zheng, Z, Sipe, J E, Cheng, J L
Format: Article
Language:English
Subjects:
Bilayers
Chemical potential
Electron states
Graphene
Mathematical analysis
Optical activity
Tensors
Online Access:Get full text
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Summary:We theoretically study the optical activity in a doped system and derive the optical activity tensor from a light wavevector-dependent linear optical conductivity. Although the light-matter interaction is introduced through the velocity gauge from a minimal coupling Hamiltonian, we find that the well-known ``false divergences'' problem can be avoided in practice if the electronic states are described by a finite band effective Hamiltonian, such as a few-band tight-binding model. The expression we obtain for the optical activity tensor is in good numerical agreement with a recent theory derived for an undoped topologically trivial gapped system. We apply our theory to the optical activity of a gated twisted bilayer graphene, with a detailed discussion of the dependence of the results on twist angle, chemical potential, gate voltage, and location of rotation center forming the twisted bilayer graphene.
ISSN:2331-8422
DOI:10.48550/arxiv.2210.03960