Rashba Sandwiches with Topological Superconducting Phases

TL;DR

This paper proposes a heterostructure with tunable topological superconducting phases, featuring helical, chiral, or unidirectional edge states, achieved through conventional ingredients and parameter adjustments.

Contribution

It introduces a bilayer Rashba heterostructure capable of hosting multiple topological phases with different edge states, controlled by Zeeman field and chemical potential.

Findings

Presence of helical, chiral, and unidirectional edge states.

Tunable topological phases via Zeeman field and chemical potential.

Realization of topological phases with conventional materials.

Abstract

We introduce a versatile heterostructure harboring various topological superconducting phases characterized by the presence of helical, chiral, or unidirectional edge states. Changing parameters, such as an effective Zeeman field or chemical potential, one can tune between these three topological phases in the same setup. Our model relies only on conventional non-topological ingredients. The bilayer setup consists of an s-wave superconductor sandwiched between two two-dimensional electron gas layers with strong Rashba spin-orbit interaction. The interplay between two different pairing mechanisms, proximity induced direct and crossed Andreev superconducting pairings, gives rise to multiple topological phases. In particular, helical edge states occur if crossed Andreev superconducting pairing is dominant. In addition, an in-plane Zeeman field leads to a 2D gapless topological phase with unidirectional edge states, which were previously predicted to exist only in non-centrosymmetric superconductors. If the Zeeman field is tilted out of the plane, the system is in a topological phase hosting chiral edge states.