Self-Organized Topological State with Majorana Fermions

TL;DR

This paper proposes a self-organizing quantum wire system of magnetic atoms on a superconductor that naturally tunes itself into a topological phase supporting Majorana fermions, simplifying experimental realization.

Contribution

It introduces a self-tuning mechanism in a quantum wire system that achieves topological superconductivity without fine tuning of parameters.

Findings

System self-adjusts to support topological phase

Realizes Kitaev paradigm dynamically

Supports Majorana fermions in a natural setting

Abstract

Topological phases, quite generally, are difficult to come by. They either occur under rather extreme conditions (e.g. the quantum Hall liquids, which require high sample purity, strong magnetic fields and low temperatures) or demand fine tuning of system parameters, as in the majority of known topological insulators. Many perfectly sensible topological phases, such as the Weyl semimetals and topological superconductors, remain experimentally undiscovered. Here we introduce a system in which a key dynamical parameter adjusts itself in response to the changing external conditions so that the ground state naturally favours the topological phase. The system consists of a quantum wire formed of individual magnetic atoms placed on the surface of an ordinary s-wave superconductor. It realizes the Kitaev paradigm of topological superconductivity when the wavevector characterizing the emergent spin helix dynamically self-tunes to support the topological phase.