Anomalous Aharonov-Bohm Conductance Oscillations from Topological Insulator Surface States

We study Aharonov-Bohm (AB) conductance oscillations arising from the surface states of a topological insulator nanowire, when a magnetic field is applied along its length. With strong surface disorder, these oscillations are predicted to have a component with anomalous period Phi(0) hc/e, twice the conventional period. The conductance maxima are achieved at odd multiples of 1/2 Phi(0), implying that a pi AB phase for electrons strengthens the metallic nature of surface states. This effect is special to topological insulators, and serves as a defining transport property. A key ingredient, the surface curvature induced Berry phase, is emphasized here. We discuss similarities and differences from recent experiments on Bi2Se3 nanoribbons, and optimal conditions for observing this effect.