Majorana fermions in superconducting helical magnets

TL;DR

This paper predicts that surfaces of rare-earth superconducting helical magnets naturally host Majorana modes, which could be experimentally observed due to their large energy scales and lack of fine-tuning requirements.

Contribution

It demonstrates that Majorana fermions can emerge in superconducting helical magnets without fine-tuning, highlighting their potential for experimental detection.

Findings

Surfaces host a finite density of zero-energy Majorana modes.

Majorana modes contribute to divergent zero-energy density of states.

Discrete Majorana modes can be isolated in wire geometries.

Abstract

In a variety of rare-earth based compounds singlet superconductivity coexists with helical magnetism. Here we demonstrate that surfaces of these systems should generically host a finite density of zero-energy Majorana modes. In the limit of vanishing disorder, these modes lead to a divergent contribution to zero-energy density of states and to zero-temperature entropy proportional to the sample surface area. When confined to a wire geometry, a discrete number of Majorana modes can be isolated. The relatively large characteristic energy scales for superconductivity and magnetism, compared to other proposals, as well as the lack of need for fine-tuning, make helical magnetic superconducting compounds favorable for the observation and experimental investigation of Majorana fermions.