Control of Andreev Reflection via a Single-Molecule Orbital
Abstract
Charge transport across a single-molecule junction fabricated from a normal-metal tip, a phthalocyanine, and a conventional superconductor in a scanning tunneling microscope is explored as a function of the gradually closed vacuum gap. The phthalocyanine (2H-Pc) molecule and its pyrrolichydrogen-abstracted derivative (Pc) exhibit vastly different behavior. Andreev reflection across the 2H-Pc contact exhibits a temporary enhancement that diminishes with increasing conductance. The hybridization of 2H-Pc with the tip at contact formation gives rise to a Kondo-screened molecular magnetic moment. In contrast, the single-Pc junction lacks Andreev reflection in the same conductance range. Spectroscopies and supporting nonequilibrium Green function calculations highlight the importance of a molecular orbital close to the Fermi energy for Andreev reflection.
Keywords
Cite
@article{arxiv.2504.01635,
title = {Control of Andreev Reflection via a Single-Molecule Orbital},
author = {Lorenz Meyer and Jose L. Lado and Nicolas Néel and Jörg Kröger},
journal= {arXiv preprint arXiv:2504.01635},
year = {2025}
}