Magnetoconductance, Quantum Hall Effect, and Coulomb Blockade in Topological Insulator Nanocones

TL;DR

This paper explores the unique magnetotransport phenomena in topological insulator nanocones, revealing quantized conductance, Landau level resonances, and Coulomb blockade effects, with potential applications in Dirac electron optics.

Contribution

It introduces topological insulator nanocones as a new platform to observe mesoscopic transport phenomena, including topological hinge states and Coulomb blockade, under experimentally accessible conditions.

Findings

Quantized conductance due to hinge states

Resonant transmission through Dirac Landau levels

Coulomb blockade effects in nanocone junctions

Abstract

Magnetotransport through cylindrical topological insulator (TI) nanowires is governed by the interplay between quantum confinement and geometric (Aharonov-Bohm and Berry) phases. Here, we argue that the much broader class of TI nanowires with varying radius -- for which a homogeneous coaxial magnetic field induces a varying Aharonov-Bohm flux that gives rise to a non-trivial mass-like potential along the wire -- is accessible by studying its simplest member, a TI nanocone. Such nanocones allow to observe intriguing mesoscopic transport phenomena: While the conductance in a perpendicular magnetic field is quantized due to higher-order topological hinge states, it shows resonant transmission through Dirac Landau levels in a coaxial magnetic field. Furthermore, it may act as a quantum magnetic bottle, confining surface Dirac electrons and leading to a largely interaction-dominated regime of Coulomb blockade type. We show numerically that the above-mentioned effects occur for experimentally accessible values of system size and magnetic field, suggesting that TI nanocone junctions may serve as building blocks for Dirac electron optics setups.