Ultrapure Multilayer Graphene in Bromine Intercalated Graphite

TL;DR

This paper studies the optical properties of bromine intercalated graphite, revealing ultrapure graphene layers with high mobility, and offers new insights into multilayer graphene's electronic behavior.

Contribution

It provides a novel interpretation of optical data showing ultrapure graphene signatures in bromine-intercalated graphite, highlighting high mobility multilayer components.

Findings

Detection of new absorption features below 620 meV.

Identification of ultrapure bilayer and single-layer graphene signatures.

Observation of supermetallic conductivity with high carrier mobility.

Abstract

We investigate the optical properties of bromine intercalated highly orientated pyrolytic graphite (Br-HOPG) and provide a novel interpretation of the data. We observe new absorption features below 620 meV which are absent in the absorption spectrum of graphite. Comparing our results with those of theoretical studies on graphite, single and bilayer graphene as well as recent optical studies of multilayer graphene, we conclude that Br-HOPG contains the signatures of ultrapure bilayer, single layer graphene, and graphite. The observed supermetallic conductivity of Br-HOPG is identified with the presence of very high mobility (~ 121,000 cm2V-1s-1 at room temperature and at very high carrier density) multilayer graphene components in our sample. This could provide a new avenue for single and multilayer graphene research.