Topological insulators are bulk insulators with a metallic surface which can be described, in the simplest case, by a single Dirac fermion. What are the properties of this metallic state when the surface is curved, such as in a cylindrical wire? How are these properties revealed in experiments, in particular in quantum transport? Are there phenomena unique to this system?
The metallic surface of a topological insulator nanowire turns out to be gapped. This is an effect of the Dirac fermion's non-trivial Berry phase as it winds around the cylindrical surface. A magnetic flux along the length of the wire can cancel this Berry phase and close the gap, thereby giving rise to the presence of a perfectly transmitted mode. This leads to various characteristic transport phenomena in these wires, such as magneto-conductance oscillations with period h/e, and a distinct peak in the supercurrent in a Josephson junction setup.
For further reading see:
- Roni Ilan, Jens H. Bardarson, H. -S. Sim, Joel E. Moore, arXiv:1305.2210v1.
- Jens H. Bardarson, Joel E. Moore, Rep. Prog. Phys. 76, 056501 (2013).
- J. H. Bardarson, P. W. Brouwer, J. E. Moore, Phys. Rev. Lett. 105, 156803 (2010).
- J. H. Bardarson, J. Phys. A: Math. Theor. 41, 405203, (2008).
- J. H. Bardarson, J. Tworzydło, P. W. Brouwer, C. W. J. Beenakker, Phys. Rev. Lett. 99, 106801 (2007)