Phase-manipulation-induced Majorana Mode and Braiding Realization in Iron-based Superconductor Fe(Te,Se)

TL;DR

This paper demonstrates how phase manipulation in Fe(Te,Se) superconductors can induce Majorana modes and proposes a device for braiding these modes, advancing topological quantum computing.

Contribution

It reveals that ferromagnetic order at domain walls induces topological surface states and proposes a junction device for Majorana braiding in Fe(Te,Se).

Findings

Ferromagnetism at domain walls induces Majorana modes.

A surface junction can create and fuse Majorana zero modes.

Potential application in topological quantum computation.

Abstract

Recent experiment reported the evidence of dispersing one-dimensional Majorana mode trapped by the crystalline domain walls in FeSe$_{0.45}$Te$_{0.55}$. Here, we perform the first-principles calculations to show that iron atoms in the domain wall spontaneously form the ferromagnetic order in line with orientation of the wall. The ferromagnetism can impose a $\pi$ phase difference between the domain-wall-separated surface superconducting regimes under the appropriate width and magnetization of the wall. Accordingly, the topological surface superconducting state of FeSe$_{0.45}$Te$_{0.55}$ can give rise to one-dimensional Majorana modes trapped by the wall. More interestingly, we further propose a surface junction in the form of FeSe$_{0.45}$Te$_{0.55}$/ferromagnet/FeSe$_{0.45}$Te$_{0.55}$, which can be adopted to create and fuse the Majorana zero modes through controlling the width or magnetization of the interior ferromagnetic barrier. The braiding and readout of Majorana zero modes can be realized by the designed device. Such surface junction has the potential application in the superconducting topological quantum computation.