  We validate the linear dispersion relation and resolve the Dirac cone on the
surface of a single Bi2Te3 nanowire via a combination of field-effect and
magnetoresistance measurements by which we unambiguously prove the topological
insulator nature of the nanowire surface states. Moreover we show that the
experimentally determined carrier concentration, mobility and cyclotron mass of
the surface states are in excellent agreement with relativistic models. Our
method provides a facile way to identify topological insulators that too small
for angle-resolved photo emission spectroscopy.
