Interplay between classical magnetic moments and superconductivity in quantum one-dimensional conductors: toward a self-sustained topological Majorana phase

TL;DR

This paper demonstrates that a 1D electronic system coupled with classical magnetic moments and a superconductor can naturally develop a topological phase supporting Majorana fermions, without fine-tuning external parameters.

Contribution

It reveals the emergence of a magnetic spiral and topological superconductivity in a 1D system due to intrinsic interactions, without external tuning.

Findings

Magnetic moments and electrons become strongly entangled at low energy.

A magnetic spiral structure emerges spontaneously.

The system enters a topological superconducting phase supporting Majorana fermions.

Abstract

We study a one-dimensional (1D) interacting electronic liquid coupled to a 1D array of classical magnetic moments and to a superconductor. We show that at low energy and temperature the magnetic moments and the electrons become strongly entangled and that a magnetic spiral structure emerges without any adjustable parameters. For strong enough coupling between the two, the 1D electronic liquid is driven into a topological superconducting phase supporting Majorana fermions without any fine-tuning of external parameters. Our analysis applies at low enough temperature to a quantum wire in proximity of a superconductor when the hyperfine interaction between electrons and nuclear spins is taken into account or to a chain of magnetic adatoms adsorbed on a superconducting surface.