▎ 摘　　要

Magnetotransport experiments on ABC-stacked suspended trilayer graphene reveal a complete splitting of the 12-fold degenerated lowest Landau level, and, in particular, the opening of an exchange-driven gap at the charge neutrality point. A quantitative analysis of distinctness of the quantum Hall plateaus as a function of field yields a hierarchy of the filling factors: nu = 6, 4, and 0 are the most pronounced, followed by nu = 3, and finally nu = 1, 2, and 5. Apart from the appearance of a nu = 4 state, which is probably caused by a layer asymmetry, this sequence is in agreement with Hund's rules for ABC-stacked trilayer graphene.