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.
@article{arxiv.0907.1111,
title = {Supermetallic conductivity in bromine-intercalated graphite},
author = {S. Tongay and J. Hwang and D. B. Tanner and H. K. Pal and D. Maslov and A. F. Hebard},
journal= {arXiv preprint arXiv:0907.1111},
year = {2013}
}