Majorana fermions in finite-size strips in the presence of orbital effects: what is the Majorana polarization telling us?

TL;DR

This study numerically investigates Majorana bound states in finite-size Rashba-coupled superconducting strips, revealing multiple pairs and extended topological regions influenced by orbital effects, with a focus on Majorana polarization insights.

Contribution

It demonstrates that finite-size Rashba superconducting strips can host multiple Majorana pairs and that orbital effects extend topological regions while reducing the energy gap.

Findings

Multiple Majorana pairs can exist in the system.

Orbital effects extend the topological phase regions.

The energy gap protecting Majoranas is reduced by orbital effects.

Abstract

We study numerically the formation of Majorana bound states in a finite-size quasi-one-dimensional square-lattice strip with Rashba spin-orbit coupling, in the presence of a proximity-induced superconducting pairing and a magnetic field perpendicular to the strip. We take into account both the Zeeman and orbital effects of the field. First, using the Majorana polarization, we demonstrate that such a system can host more than one pair of Majorana quasiparticles. We construct the corresponding topological phase diagram and we conclude that the topological regions are extended in the presence of orbital effects, however the gap protecting the topological states is reduced.