Scanning SQUID Imaging of Reduced Superconductivity Due to the Effect of Chiral Molecule Islands Adsorbed on Nb

Abstract

Unconventional superconductivity was realized in systems comprising a monolayer of magnetic adatoms adsorbed on conventional superconductors, forming Shiba-bands. Another approach to induce unconventional superconductivity and 2D Shiba-bands was recently introduced, namely, by adsorbing chiral molecules (ChMs) on conventional superconductors, which act in a similar way to magnetic impurities as verified by conductance spectroscopy. However, the fundamental effect ChMs have on the strength of superconductivity has not yet been directly observed and mapped. In this work, local magnetic susceptometry is applied on heterostructures comprising islands of ChMs (α-helix L-polyalanine) monolayers adsorbed on Nb. It is found that the ChMs alter the superconducting landscape, resulting in spatially-modulated weaker superconductivity. Surprisingly, the reduced diamagnetic response is located along the perimeter of the islands with respect to both their interior and the bare Nb. The authors suggest that topological edge-states forming at the edges are the source of the reduced superconductivity, akin to the case of magnetic islands. The results pave new paths for the realization of topological-superconductivity-based devices with changing order parameter.