Interaction of hydrogen molecules with superconducting nanojunctions

TL;DR

This study investigates how hydrogen molecules interact with superconducting nanojunctions made of various metals, revealing metal-dependent interactions and effects on mechanical and electronic properties without forming single-molecule bridges.

Contribution

It provides the first detailed analysis of hydrogen's interaction with different superconducting nanojunctions, highlighting metal-specific behaviors and the impact on conductance and transmission eigenvalues.

Findings

Strong hydrogen interaction with Nb, Ta, and Al

Minimal interaction with Sn and In

No evidence of single-molecule bridge formation

Abstract

In this paper the interaction of hydrogen molecules with atomic-sized superconducting nanojunctions is studied. It is demonstrated by conductance histogram measurements that the superconductors niobium, tantalum and aluminum show a strong interaction with hydrogen, whereas for lead a slight interaction is observed, and for tin and indium no significant interaction is detectable. For Nb, Ta and Pb subgap method is applied to determine the transmission eigenvalues of the nanojunctions in hydrogen environment. It is shown, that in Nb and Ta the mechanical behavior of the junction is spectacularly influenced by hydrogen reflected by extremely long conductance traces, but the electronic properties based on the transmission eigenvalues are similar to those of pure junctions. Evidences for the formation of a single-molecule bridge between the electrodes -- as in recently studied platinum hydrogen system -- were not found.