Engineering three-dimensional topological insulators in Rashba-type spin-orbit coupled heterostructures

TL;DR

This paper proposes a theoretical method to engineer three-dimensional topological insulators by stacking bilayers of 2D Fermi gases with opposite Rashba spin-orbit coupling, enabling tunable, artificial topological phases.

Contribution

It introduces a novel design principle for creating 3D topological insulators using layered heterostructures with controllable spin-orbit coupling and inter-layer tunneling.

Findings

Topological phase transition occurs above a critical number of Rashba-bilayers.

A single spin-polarized Dirac cone forms at the $a9$-point in the topological phase.

The approach allows for tunable, artificial topological insulators bypassing bulk crystal limitations.

Abstract

Topological insulators represent a new class of quantum phase defined by invariant symmetries and spin-orbit coupling that guarantees metallic Dirac excitations at its surface. The discoveries of these states have sparked the hope of realizing nontrivial excitations and novel effects such as a magnetoelectric effect and topological Majorana excitations. Here we develop a theoretical formalism to show that a three dimensional topological insulator can be designed artificially via stacking bilayers of two-dimensional Fermi gases with opposite Rashba-type spin-orbit coupling on adjacent layers, and with inter-layer quantum tunneling. We demonstrate that in the stack of bilayers grown along a (001)-direction, a nontrivial topological phase transition occurs above a critical number of Rashba-bilayers. In the topological phase we find the formation of a single spin-polarized Dirac cone at the $\Gamma$-point. This approach offers an accessible way to design artificial topological insulators in a set up that takes full advantage of the atomic layer deposition approach. This design principle is tunable and also allows us to bypass limitations imposed by bulk crystal geometry.