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Control of Andreev Reflection via a Single-Molecule Orbital

Lorenz Meyer1, Jose L. Lado2, Nicolas Néel1, and Jörg Kröger1

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Phys. Rev. Lett. 134, 146201 – Published 9 April, 2025

DOI: https://doi.org/10.1103/PhysRevLett.134.146201

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 pyrrolic-hydrogen-abstracted derivative (Pc) exhibit vastly different behavior. Andreev reflection across the 2H-Pc contact exhibits a temporary enhancement that diminishes again with increasing conductance. In contrast, the single-Pc junction lacks Andreev reflection in the same conductance range. Spectroscopies and supporting nonequilibrium Green’s function calculations highlight the importance of a molecular orbital close to the Fermi energy for Andreev reflection.

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Superconductivity Traverses a Single Molecule Bridge

Published 9 April, 2025

A single molecule provides a controllable connection between a normal metal and a superconductor.    

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Phys. Rev. Lett. 134, 146201– Published 9 April, 2025
  • Received 12 November 2024
  • Accepted 21 February 2025
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