Delocalisation of Majorana quasiparticles in plaquette--nanowire hybrid system

TL;DR

This paper explores how Majorana quasiparticles behave in a hybrid system combining one-dimensional nanowires and two-dimensional plaquettes, revealing their delocalisation and potential leakage into the nanocluster corners.

Contribution

It introduces a novel mixed-dimensional system and analyzes the delocalisation properties of Majorana modes within it, expanding understanding of topological states in hybrid structures.

Findings

Majorana modes can delocalise and leak from nanowires into nanoclusters.

Delocalisation tends to occur towards the corners of the 2D plaquette.

The system can host topologically non-trivial superconducting states.

Abstract

Interplay between superconductivity, spin-orbit coupling and magnetic field can lead to realisation of the topologically non--trivial states which in finite one dimensional nanowires are manifested by emergence of a pair of zero-energy Majorana bound states. On the other hand, in two dimensional systems spin current contributed by the edge states might appear. We investigate novel properties of the bound states in a system of mixed dimensionality, composed of one-dimensional nanowire connected with two-dimensional plaquette. This setup could be patterned epitaxially, e.g. using heterostructure analogous to what has been reported recently by F. Nichele et al., Phys. Rev. Lett. 119, 136803 (2017). We study this system, assuming either its part or the entire structure to be in topologically non--trivial superconducting state. Our results predict delocalisation of the Majorana modes, upon leaking from the nanowire to the nanocluster with some tendency towards its corners.