We report markedly different transport properties of ABA- and ABC-stacked
trilayer graphenes. Our experiments in double-gated trilayer devices provide
evidence that a perpendicular electric field opens an energy gap in the ABC
trilayer, while it causes the increase of a band overlap in the ABA trilayer.
In a perpendicular magnetic field, the ABA trilayer develops quantum Hall
plateaus at filling factors of \nu = 2, 4, 6... with a step of \Delta \nu = 2,
whereas the inversion symmetric ABC trilayer exhibits plateaus at \nu = 6 and
10 with 4-fold spin and valley degeneracy.Comment: 4 pages, 4 figure