New experiments confirms that trilayer graphene exhibits the quantum hall effect. In a single layer of graphene, electrons 'race around' as if they have no mass. In a bi-layer graphene, this changes - and they behave as they do have a mass.
It was predicted that trilayer graphene will exhibit the quantum hall effect, but this was difficult to show - mostly because there are several ways to construct the trilayer graphene. If the Top and bottom sheets are lined up, sandwich-style, the material behaves like a metal. But when layers step upward at a slant, like stairs, the Quantum Hall effect begins.