# Helical Hinge Majoranas in Iron-Based Superconductors

## TL;DR

This paper proposes a minimal model for iron-based superconductors that predicts the existence of 1D helical Majorana modes at hinges, indicating a new platform for higher-order topological superconductivity.

## Contribution

It introduces a minimal theoretical model showing intrinsic hinge Majorana modes in iron-based superconductors without vortices, expanding the understanding of topological superconductivity.

## Key findings

- Hinge Majorana modes are predicted at the boundaries between different surface orientations.
- The model demonstrates these modes are stable and potentially observable experimentally.
- Supports the idea of higher-order topological superconductivity in iron-based materials.

## Abstract

Motivated by recent experiments on FeTe$_{1-x}$Se$_{x}$, we construct an explicit minimal model of an iron-based superconductor with band inversion at the $Z$ point and non-topological bulk $s_{\pm}$ pairing. While there has been considerable interest in Majorana zero modes localized at vortices in such systems, we find that our model - without any vortices - intrinsically supports 1D helical Majorana modes localized at the hinges between (001) and (100) or (010) surfaces, suggesting that this is a viable platform for observing "higher-order" topological superconductivity. We provide a general theory for these hinge modes and discuss their stability and experimental manifestation. Our work indicates the possible experimental observability of hinge Majoranas in iron-based topological superconductors.