Department of Physics

Electrons in monolayer graphene are described by massless Dirac electrons, which exhibit unique quantum phenomena due to the pseudospin and Berry phase of the massless electrons. In this talk, I will discuss our effort in probing massive Dirac electrons in gapped bilayer graphene, which can be described by a quantum valley Hall insulator with non-trivial Chern number for individual valleys. We show that a tunable bandgap up to 200 meV can be induced in bilayer graphene with electrical gating. In addition, we observe a topologically protected 1D conducting channel at the domain boundary of AB-BA bilayers, which can be attributed to the quantum valley Hall edge states in gapped bilayer graphene. I will also discuss one-dimensional plasmon arising from Luttinger liquid of Dirac electrons in metallic carbon nanotubes, which exhibit semi-quantized propagation speed and remarkable sub-wavelength plasmon confinement.