Ab initio study of Proximity-Induced Superconductivity in PbTe/Pb heterostructures

TL;DR

This study uses ab initio calculations to analyze superconductivity in PbTe/Pb heterostructures, revealing proximity-induced gaps and anisotropic pairing, but finds a large Schottky barrier that may hinder Majorana zero modes.

Contribution

First ab initio analysis of superconductivity and proximity effects in PbTe/Pb heterostructures, providing detailed insights into their electronic and superconducting properties.

Findings

Proximity-induced superconducting gap observed on PbTe side.

Anisotropic pairing potential necessary for unconventional superconductivity.

Large Schottky barrier prevents Majorana zero modes.

Abstract

Semiconductor-superconductor hybrid devices have been proposed as promising platforms for detecting and analyzing Majorana zero modes, which find applications in topological quantum computing. In this work, we solve the Kohn-Sham Density Functional Theory and Bogoliubov-de Gennes equations to describe the normal and superconducting properties of a PbTe/Pb heterostructure. We resolve a proximity-induced superconducting gap on the PbTe side. The hybridization between PbTe and Pb causes the emergence of a soft Bardeen-Cooper-Schrieffer-like superconducting gap. We compute the anomalous charge density in real space, estimating its decay length and showing that the pairing potential is anisotropic, which is a necessary condition for unconventional superconductivity. Contrary to the models that predict Majorana zero modes in these interfaces, we find a significantly large Schottky barrier in the normal state preventing the emergence of zero modes. Our findings strengthen the understanding of the physics governing PbTe/Pb hybrid devices and their viability for Majorana zero modes applications.