Unusual transport properties in carbon based nanoscaled materials: nanotubes and graphene

The massless Dirac particle moving at the speed of light has been a fascinating subject in relativistic quantum physics. Nanoscale graphitic materials, such as carbon nanotubes and graphene, now provide us with an opportunity to investigate such exotic effects in low-energy condensed matter systems. The unique electronic band structure of graphene lattice provides a linear dispersion relation where the Fermi velocity replaces the role of the speed of light in the usual Dirac Fermion spectrum. Recent experimental studies reveal that such unconventional electronic structure in graphitic carbon leads to unique electronic transport phenomena in 1-dimensional carbon nanotubes and 2-dimensional graphene. Combined with semiconductor device fabrication techniques and the development of new methods of nanoscaled material synthesis/manipulation enables us to investigate mesoscopic transport phenomena in these materials. The exotic quantum transport behavior discovered in these materials, such as room temperature ballistic transport, unusual half-integer quantum Hall effect, and a non-zero Berrys phase in magneto-oscillations will be discussed in the connection to Dirac Fermion description in graphitic systems.