Interface-Bound States and Majorana Zero Modes in Lateral Heterostructures of Bi$_2$Se$_3$ and Sb$_2$Te$_3$ with Proximity-Induced Superconductivity

TL;DR

This paper investigates the emergence of Majorana zero modes at interfaces in a heterostructure of topological insulators Bi$_2$Se$_3$ and Sb$_2$Te$_3$ with superconductivity, providing theoretical models and predictions for experimental detection.

Contribution

It introduces an advanced Dirac model and analytical solutions for interface-bound states, demonstrating the presence and robustness of Majorana zero modes in the heterostructure.

Findings

Identification of zero-energy Majorana modes at the interface

Analytical solutions for bound states using BdG formalism

Predictions for experimental tunneling spectroscopy signatures

Abstract

We present a comprehensive investigation into the emergence of interface-bound states, particularly Majorana zero modes (MZMs), in a lateral heterostructure composed of two three-dimensional topological insulators (TIs), Bi$_2$Se$_3$ and Sb$_2$Te$_3$, under the influence of proximity-induced superconductivity from niobium (Nb) contacts. We develop an advanced two-dimensional Dirac model for the topological surface states (TSS), incorporating spatially varying chemical potentials and s-wave superconducting pairing. Using the Bogoliubov-de Gennes (BdG) formalism, we derive analytical solutions for the bound states and compute the local density of states (LDOS) at the interface, revealing zero-energy modes characteristic of MZMs. The topological nature of these states is rigorously analyzed through winding numbers and Pfaffian invariants, and their robustness is explored under various physical perturbations, including gating effects. Our findings highlight the potential of this heterostructure as a platform for topological quantum computing, with detailed predictions for experimental signatures via tunneling spectroscopy.