Topological properties of finite-size heterostructures of magnetic topological insulators and superconductors

TL;DR

This paper investigates the topological phases of magnetic topological insulator and superconductor heterostructures in 2D and 1D geometries, revealing various phases with chiral Majorana edge states and Majorana bound states based on geometric and material parameters.

Contribution

It introduces a comprehensive analysis of topological phases in MTI/SC heterostructures with varying geometries and parameters using effective Hamiltonians.

Findings

Different topological phases with CMESs and MBSs are identified.

Coexistence of CMESs and MBSs occurs under certain conditions.

Phase transitions depend on chemical potential, magnetic doping, and geometry.

Abstract

Heterostructures of magnetic topological insulators (MTIs) and superconductors (SCs) in two-dimensional (2D) slab and one-dimensional (1D) nanoribbon geometries have been predicted to host, respectively, chiral Majorana edge states (CMESs) and Majorana bound states (MBSs). We study the topological properties of such MTI/SC heterostructures upon variation of the geometry from wide slabs to quasi-1D nanoribbon systems and as a function of the chemical potential, the magnetic doping, and the induced superconducting pairing potential. To do so, we construct effective symmetry-constrained low-energy Hamiltonians accounting for the real-space confinement. For a nanoribbon geometry with finite width and length, we observe different phases characterized by CMESs, MBSs, as well as coexisting CMESs and MBSs, as the chemical potential, the magnetic doping and/or the width are varied.