Origin of Universal Optical Conductivity and Optical Stacking Sequence Identification in Multilayer Graphene

TL;DR

This paper explains that the universal optical conductivity in multilayer graphene arises from an emergent chiral symmetry, linking stacking sequence to optical properties across frequencies.

Contribution

It reveals the fundamental origin of universal optical conductivity in multilayer graphene and connects stacking sequence to optical behavior.

Findings

Universal optical conductivity is due to emergent chiral symmetry.

Conductivity scales with the number of layers, N.

Stacking sequence influences intermediate frequency conductivity trends.

Abstract

We show that the origin of the universal optical conductivity in a normal $N$-layer graphene multilayer is an emergent chiral symmetry which guarantees that $\sigma(\omega)=N\sigma_{uni}$ in both low and high frequency limits. [$\sigma_{uni}=(\pi/2) e^2/h$]. We use this physics to relate intermediate frequency conductivity trends to qualitative characteristics of the multilayer stacking sequence.