Caroli-de Gennes-Matricon Analogs in Full-Shell Hybrid Nanowires

TL;DR

This paper investigates subgap states in full-shell hybrid nanowires, revealing analogs of vortex core states that are observable as van Hove singularities, and explores their evolution under magnetic fields.

Contribution

It demonstrates the existence of Caroli-de Gennes-Matricon analogs in hybrid nanowires and characterizes their properties and magnetic field dependence, providing new insights into their structure.

Findings

CdGM analogs manifest as one-dimensional van Hove singularities

Energy spacings are comparable to the superconducting gap and independent of Fermi energy

Evolution with magnetic field matches theoretical predictions

Abstract

We report tunneling spectroscopy of Andreev subgap states in hybrid nanowires with a thin superconducting full-shell surrounding a semiconducting core. The combination of the quantized fluxoid of the shell and the Andreev reflection at the superconductor-semiconductor interface gives rise to analogs of Caroli-de Gennes-Matricon (CdGM) states found in Abrikosov vortices in type-II superconductors. Unlike in metallic superconductors, CdGM analogs in full-shell hybrid nanowires manifest as one-dimensional van Hove singularities with energy spacings comparable to the superconducting gap and independent of the Fermi energy, making them readily observable. Evolution of these analogs with axial magnetic field, skewed within the Little-Parks lobe structure, is consistent with theory and yields information about the radial distribution and angular momenta of the corresponding subbands.