Helical spin texture and interference of Majorana bound states in one-dimensional topological superconductor

TL;DR

This paper explores the helical spin texture and interference patterns of Majorana bound states in a 1D topological superconductor derived from a quantum spin-Hall insulator, revealing unique spin properties and experimental signatures.

Contribution

It demonstrates the helical spin texture of Majorana bound states and proposes experimental detection methods using scanning tunneling microscopy and spectroscopy.

Findings

Helical spin texture with a pitch proportional to Fermi momentum.

Energy spectrum mapped as ±E cos(φ/2) showing protected quasiparticle excitations.

Experimental approach to confirm non-mixing of quasiparticles due to parity conservation.

Abstract

We investigate one-dimensional (1D) Majorana bound states (MBSs) realized in terms of the helical edge states of a 2D quantum spin-Hall insulator (QSHI) in a heterostructure with a superconducting substrate and two ferromagnetic insulators (FIs). By means of Bogoliubov-de Gennes approach we demonstrate that there is a helical spin texture in the MBS wave function with a pitch proportional to the Fermi momentum of the helical edge states of QSHI. Moreover, simultaneous detection on local density of states by scanning tunneling microscopy and spectroscopy at a position close to one FI edge and at the midpoint between two FIs can not only map out the energy spectrum $\pm E \cos(\phi/2)$, but also prove experimentally that the two quasiparticle excitations do not mix with each other as protected by the parity conservation associated with the MBSs.