Supermetallic conductivity in bromine-intercalated graphite

TL;DR

This study demonstrates that bromine intercalation in graphite significantly enhances in-plane electrical conductivity, achieving supermetallic levels due to hole doping and increased interlayer spacing, confirmed through multiple measurement techniques.

Contribution

It reveals that bromine intercalation induces supermetallic conductivity in graphite by hole doping and structural modification, a novel finding in intercalated graphene materials.

Findings

Increased in-plane conductivity surpassing copper at low temperatures.

Hole doping confirmed by magnetotransport and magnetic susceptibility.

Enhanced mobility and anisotropy indicating weak interlayer coupling.

Abstract

Exposure of highly oriented pyrolytic graphite to bromine vapor gives rise to in-plane charge conductivities which increase monotonically with intercalation time toward values (for ~6 at% Br) that are significantly higher than Cu at temperatures down to 5 K. Magnetotransport, optical reflectivity and magnetic susceptibility measurements confirm that the Br dopes the graphene sheets with holes while simultaneously increasing the interplanar separation. The increase of mobility (~ 5E4 cm^2/Vs at T=300 K) and resistance anisotropy together with the reduced diamagnetic susceptibility of the intercalated samples suggests that the observed supermetallic conductivity derives from a parallel combination of weakly-coupled hole-doped graphene sheets.