Majorana fermions at odd junctions in a wire network of ferromagnetic impurities

TL;DR

This paper predicts the emergence of Majorana fermions at odd junctions in a ferromagnetic impurity wire network on a superconductor, offering experimentally accessible signatures for topological quantum states.

Contribution

It demonstrates the presence of Majorana fermions at odd junctions in a ferromagnetic impurity wire network with strong Rashba spin-orbit coupling, highlighting a new topological feature.

Findings

Majorana fermions appear at wire end-points and odd junctions.

No low-energy states at even junctions.

Energy gap varies with Rashba coupling and impurity strength.

Abstract

We consider a wire network of ferromagnetic impurities on the surface of an $s$-wave superconductor with strong Rashba spin-orbit interaction. Within the topological phase, zero-energy Majorana fermions appear at wire end-points as well as at junctions between an odd number of wire segments, while no low-energy states are present at junctions between an even number of wire segments, providing strong experimentally accessible signatures for Majorana fermions. We also investigate the quasiparticle energy gap with respect to varying the Rashba spin-orbit coupling and magnetic impurity strength.