Magnetotransport signatures of three-dimensional topological insulator nanostructures

TL;DR

This paper investigates how the geometry and magnetic field influence electron transport in 3D topological insulator nanostructures, revealing unique conductance signatures useful for quantum device applications.

Contribution

It provides analytical and numerical analysis of magnetotransport in complex topological insulator nanostructures, highlighting new conductance phenomena due to geometry and magnetic field orientation.

Findings

Quantized conductance across kinks with half-integer flux quantum

Unique $$-periodic magnetoconductance in right-angle kinks

Magnetic field alignment controls transmission in Y-junctions

Abstract

We study the magnetotransport properties of patterned 3D topological insulator nanostructures with several leads, such as kinks or Y-junctions, near the Dirac point with analytical as well as numerical techniques. The interplay of the nanostructure geometry, the external magnetic field and the spin-momentum locking of the topological surface states lead to a richer magnetoconductance phenomenology as compared to straight nanowires. Similar to straight wires, a quantized conductance with perfect transmission across the nanostructure can be realized across a kink when the input and output channels are pierced by a half-integer magnetic flux quantum. Unlike for straight wires, there is an additional requirement depending on the orientation of the external magnetic field. A right-angle kink shows a unique $\pi$-periodic magnetoconductance signature as a function of the in-plane angle of the magnetic field. For a Y-junction, the transmission can be perfectly steered to either of the two possible output legs by a proper alignment of the external magnetic field. These magnetotransport signatures offer new ways to explore topological surface states and could be relevant for quantum transport experiments on nanostructures which can be realized with existing fabrication methods.