  Magneto-transport experiments on ABC-stacked suspended trilayer graphene
reveal a complete splitting of the twelve-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.
