Realizing Topological Superconductivity with Superlattices

TL;DR

This paper proposes a novel superlattice platform for realizing topological superconductivity that overcomes chemical potential control challenges, enabling Majorana modes and chiral edge states in one- and two-dimensional systems.

Contribution

It introduces a superlattice structure with periodic superconducting deposits, facilitating topological phases despite electrostatic screening constraints.

Findings

Majorana bound states appear at ends of 1D SC lattice.

2D px+ipy SC hosting chiral Majorana modes is realizable.

Topological phase achievable even with complete electrostatic screening.

Abstract

The realization of topological superconductors (SCs) in one or two dimensions is a highly pursued goal. Prominent proposed realization schemes include semiconductor/superconductor heterostructures and set stringent constraints on the chemical potential of the system. However, the ability to keep the chemical potential in the required range while in the presence of an adjacent SC and its accompanied screening effects, is a great experimental challenge. In this work, we study a SC lattice structure in which the SC is deposited periodically on a one- or two-dimensional sample. We demonstrate that this realization platform overcomes the challenge of controlling the chemical potential in the presence of the superconductor's electrostatic screening. We show how Majorana bound states emerge at the ends of a one-dimensional system proximity coupled to a one-dimensional SC lattice, and move on to present a SC-lattice-based realization of the two-dimensional px+ipy SC, hosting chiral Majorana modes at its edges. In particular, we establish that even when assuming the worst case of absolute screening, in which the chemical potential under the SC is completely unaffected by the external gate potential, the topological phase can be reached by tuning the chemical potential in the area not covered by the SC. Finally, we briefly discuss possible effects of Coulomb blockade on the properties of the system.