▎ 摘　　要

We experimentally investigate the conductance of a single-layer graphene ring. The Aharonov-Bohm oscillation amplitude of the four-terminal resistance is very high with a visibility up to 10%. Additionally, we investigate the amplitude and the period of the Aharonov-Bohm effect over a magnetic field range of +/-5 T. We find that, while the period remains constant, the amplitude rises by a factor of 2. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim