Non-contact Andreev reflection as a direct probe of superconductivity on the atomic scale
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 nanoand atomic-scale imaging of superconducting properties, including disordered superconductors and proximity to phase transitions.
Keywords
Cite
@article{arxiv.2202.02159,
title = {Non-contact Andreev reflection as a direct probe of superconductivity on the atomic scale},
author = {Wonhee Ko and Jose L. Lado and Petro Maksymovych},
journal= {arXiv preprint arXiv:2202.02159},
year = {2024}
}