Engineering of many-body Majorana states in a topological insulator/s-wave superconductor heterostructure

TL;DR

This paper models a vortex chain in a topological insulator/superconductor heterostructure as a two-leg Majorana ladder, demonstrating how external magnetic fields and interactions can stabilize many-body Majorana states and induce topological phase transitions.

Contribution

It introduces a model for many-body Majorana states in a vortex chain, revealing how magnetic field orientation and sample thickness control topological phases and charge-density-wave states.

Findings

Majorana zero modes can be stabilized at ladder ends with magnetic field and interactions.

Phase diagram includes topological, trivial, and charge-density-wave states.

Interaction induces topological phase transitions.

Abstract

We study a vortex chain in a thin film of a topological insulator with proximity-induced superconductivity---a promising platform to realize Majorana zero modes (MZMs)---by modeling it as a two-leg Majorana ladder. While each pair of MZMs hybridizes through vortex tunneling, we hereby show that MZMs can be stabilized on the ends of the ladder with the presence of tilted external magnetic field and four-Majorana interaction. Furthermore, a fruitful phase diagram is obtained by controlling the direction of magnetic field and the thickness of the sample. We reveal many-body Majorana states and interaction-induced topological phase transitions and also identify trivial-superconducting and commensurate/incommensurate charge-density-wave states in the phase diagram.