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

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 $Γ$-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.