▎ 摘　　要

We investigate the quantum Hall regime in a graphene flake with different levels of disorder. Under high magnetic field, an unexpected decrease in the Hall resistance occurs when only the zeroth-energy Landau level is populated. The presence of disorder rules out the expected appearance of the v = 0 quantum Hall plateau as in the case of pristine graphene. Instead, we propose an alternative explanation based on the coexistence of two types of carriers, electrons and holes, induced by high magnetic field, in the presence of disorder.