Emergent topological superconductivity at nematic domain wall of FeSe

TL;DR

This paper demonstrates that nematic domain walls in FeSe can host emergent one-dimensional topological superconductivity with Majorana bound states, offering a new platform for realizing Majorana fermions in solid-state systems.

Contribution

It reveals that nematic domain walls in FeSe act as emergent hybrid systems capable of supporting topological superconductivity and Majorana states, a novel concept in the field.

Findings

Domain walls induce spin-triplet pairing in FeSe.

Zero energy bound states at domain walls satisfy Majorana conditions.

Potential for experimental detection using scanning tunneling microscopy.

Abstract

One dimensional hybrid systems play an important role in the search for topological superconductivity. Nevertheless, all one dimensional hybrid systems so far have been externally defined. Here we show that one-dimensional domain wall in a nematic superconductor can serve as an emergent hybrid system in the presence of spin-orbit coupling. As a concrete setting we study the domain wall between nematic domains in FeSe, which is well established to be a nematic superconductor. We first show on the symmetry grounds that spin-triplet pairing can be induced at the domain wall by constructing a Ginzburg-Landau theory. We then demonstrate using Bogoliubov-de Gennes approach that such nematic domain wall supports zero energy bound states which would satisfy Majorana condition. Well-known existence of these domain walls at relatively high temperatures, which can in principle be located and investigated with scanning tunneling microscopy, presents new opportunities for a search for realization of Majorana bound states.