Electrical switching and interferometry of massive Dirac particles in topological insulators constrictions

TL;DR

This paper demonstrates electrical control of charge and spin transport in topological insulator nanoconstrictions, utilizing quantum interference and tunneling effects to switch edge states for potential spintronic applications.

Contribution

It introduces a novel method to electrically switch topological edge states in nanoconstrictions using interferometry and tunneling, enabling precise control of charge and spin currents.

Findings

Electrical switching of edge channels via gate voltages.

Observation of quantum size and confinement effects.

Full characterization of charge and spin currents through Fabry-Perot physics.

Abstract

We investigate the electrical switching of charge and spin transport in a topological insulator nanoconstriction in a four terminal device. The switch of the edge channels is caused by the coupling between edge states which overlap in the constriction and by the tunneling effects at the contacts and therefore can be manipulated by tuning the applied voltages on the split-gate or by geometrical etching. The switching mechanism can be conveniently studied by electron interferometry involving the measurements of the current in different configurations of the side gates, while the applied bias from the external leads can be tuned to obtain pure charge or pure spin currents (charge- and spin- bias configurations). Relevant signatures of quantum confinement effects, quantum size effects and energy gap are evident in the Fabry-Perot physics of the device allowing for a full characterization of the charge and spin currents. The proposed electrical switching behavior offers an efficient tool to manipulate topological edge state transport in a controllable way.