Optical response of alternating twisted trilayer graphene

TL;DR

This paper investigates the optical properties of alternating twisted trilayer graphene using theoretical models, revealing layer-specific responses and the effects of coupling, with particular focus on magnetic and electro-magnetic responses.

Contribution

It introduces a novel theoretical framework for analyzing the optical response of alternating twisted trilayer graphene, including layer-resolved conductivities and magnetic responses.

Findings

Layer-resolved optical conductivities expressed in terms of effective bilayer and single-layer contributions.

In-plane magnetic response is negligible due to energy scale differences.

Formulation of a local electromagnetic response involving magnetic field gradients.

Abstract

We study the optical response of the alternating twisted trilayer graphene by making use of a unitary transformation for the trilayer Hamiltonian and the Kubo formulation of linear response theory. The layer-resolved optical conductivities are expressed in terms of contributions from effective twisted bilayer and single-layer systems along with their coupling. We show that the in-plane magnetic response is proportional to this coupling between the twisted bilayer and single-layer systems; and, due to the different energy scales, the in-plane magnetic response is negligibly small. We also formulate a local electro-magnetic response that involves the vertical gradients of the magnetic field and moment.