Aharonov-Bohm Oscillations in a Quasi-Ballistic 3D Topological Insulator Nanowire

Abstract

In three-dimensional topological insulators (3D TI) nanowires, transport occurs via gapless surface states where the spin is fixed perpendicular to the momentum[1-6]. Carriers encircling the surface thus acquire a πBerry phase, which is predicted to open up a gap in the lowest-energy 1D surface subband. Inserting a magnetic flux (Φ) of h/2e through the nanowire should cancel the Berry phase and restore the gapless 1D mode[7-8]. However, this signature has been missing in transport experiments reported to date[9-11]. Here, we report measurements of mechanically-exfoliated 3D TI nanowires which exhibit Aharonov-Bohm oscillations consistent with topological surface transport. The use of low-doped, quasi-ballistic devices allows us to observe a minimum conductance at Φ = 0 and a maximum conductance reaching e^2/h at Φ = h/2e near the lowest subband (i.e. the Dirac point), as well as the carrier density dependence of the transport.

9 pages, 4 figures with additional Supplement