Noncontact Andreev Reflection as a Direct Probe of Superconductivity on the Atomic Scale

Wonhee Ko, Jose L. Lado, Petro Maksymovych*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)

Abstract

Direct detection of superconductivity has long been a key strength of point-contact Andreev reflection. However, its applicability to atomic-scale imaging is limited by the mechanical contact of the Andreev probe. To this end, we present a new method to probe Andreev reflection in a tunnel junction, leveraging tunneling spectroscopy and junction tunability to achieve quantitative detection of Andreev scattering. This method enables unambiguous assignment of superconducting origins of current-carrying excitations, as well as detection of higher order Andreev processes in atomic-scale junctions. We furthermore revealed distinct sensitivity of Andreev reflection to natural defects, such as step edges, even in classical superconductors. The methodology opens a new path to nano- and atomic-scale imaging of superconducting properties, including disordered superconductors and proximity to phase transitions.

Original languageEnglish
Pages (from-to)4042−4048
Number of pages7
JournalNano Letters
Volume22
DOIs
Publication statusPublished - 25 May 2022
MoE publication typeA1 Journal article-refereed

Keywords

  • Andreev reflection
  • microscopy
  • point-contact Andreev reflection
  • superconductivity
  • tunneling

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  • -: Lado Jose AT-palkka

    Lado, J.

    01/09/202031/08/2025

    Project: Academy of Finland: Other research funding

  • -: Lado Jose AT-kulut

    Lado, J., Hyart, T., Kumar, P. & Koch, R.

    01/09/202031/08/2023

    Project: Academy of Finland: Other research funding

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