The Aharonov-Bohm Effect in a 3D topological insulator nanowire

The three dimensional topological insulator (3D TI) is a new class of material having metallic surface states characterized by gapless Dirac dispersions and novel properties such as momentum-spin locking. A TI nanowire with an insulating bulk can be described as a hollow metallic cylinder, showing Aharonov-Bohm oscillations when a magnetic flux is threaded through the axis. The magneto-conductance of a TI nanowire near the Dirac point is expected to have a minimum at zero magnetic field and an oscillation period of one magnetic flux quantum, $\Phi $ (due to a Berry phase of $\pi $ acquired by electron waves upon 2$\pi $ rotation of electron spin around the surface of the nanowire) [1]. In this talk, we discuss magneto-conductance measurements of TI (Bi$_{2}$Se$_{3})$ nanowires, measured as the gate voltage is tuned through the Dirac point. The Aharonov-Bohm oscillations switch from a conductance maximum to a minimum at zero field as the Dirac point is approached, consistent with the existence of a Berry phase in the nanowire. \\[4pt] [1] J.H. Bardarson, P.W. Brouwer, and J. E. Moore, Phys. Rev. Lett. 105, 156803 (2010).