Full electrical control of Charge and Spin conductance through Interferometry of Edge States in Topological Insulators

TL;DR

This paper demonstrates how electron interferometry in topological insulators enables full electrical control over charge and spin conductance, including the generation of pure currents, without magnetic fields.

Contribution

It introduces a novel interferometry setup in topological insulators that allows electrical tuning of conductance and spin currents via quantum point contacts.

Findings

Conductance can be tuned electrically without magnetic fields.

Negative conductance values can be achieved.

Pure charge or spin currents can be selectively generated.

Abstract

We investigate electron interferometry of edge states in Topological Insulators. We show that, when inter-boundary coupling is induced at two quantum point contacts of a four terminal setup, both Fabry-P\'erot-like and Aharonov-Bohm-like loop processes arise. These underlying interference effects lead to a full electrically controllable system, where the magnitude of charge and spin linear conductances can be tuned by gate voltages, without applying magnetic fields. In particular we find that, under appropriate conditions, inter-boundary coupling can lead to negative values of the conductance. Furthermore, the setup also allows to selectively generate pure charge or pure spin currents, by choosing the voltage bias configuration.