Fractionalization of Majorana-Ising-type quasiparticles

TL;DR

This paper theoretically explores a novel Majorana-Ising-type quasiparticle arising from a topological superconductor coupled with a magnetic impurity, revealing fractionalized zero-modes with unique tunneling and conductance properties.

Contribution

It introduces a new quasiparticle state influenced by Ising coupling in a topological superconductor-impurity system, highlighting fractionalization and zero-mode behavior.

Findings

Fractionalized Majorana zero-modes modulated by Ising interaction.

Resonant zero-mode with null Andreev conductance.

Electron tunneling character of the Majorana-like state.

Abstract

We theoretically investigate the spectral properties of a quantum impurity (QI) hosting the here proposed {Majorana-Ising-type quasiparticle (MIQ) excitation}. It arises from the coupling between a finite topological superconductor (TSC) based on a chain of magnetic adatoms-superconducting hybrid system and an integer large spin $S$ flanking the QI. Noteworthy, the spin $S$ couples to the QI via the Ising-type exchange interaction. As the Majorana zero-modes (MZMs) at the edges of the TSC chain are overlapped, we counterintuitively find a regime wherein the Ising term modulates the localization of a fractionalized and resonant MZM at the QI site. Interestingly enough, the fermionic nature of this state is revealed as purely of electron tunneling-type and most astonishingly, it has the Andreev conductance completely null in its birth. Therefore, we find that a resonant edge state appears as a zero-mode and discuss it in terms of a poor man's Majorana[Nature 614, 445 (2023)].