Magnetic-Related States and Order Parameter Induced in a Conventional Superconductor by Nonmagnetic Chiral Molecules

TL;DR

This study shows that non-magnetic chiral molecules can induce magnetic-related states and possibly triplet superconductivity in a conventional superconductor, revealing new ways to manipulate superconducting states via molecular adsorption.

Contribution

It demonstrates that non-magnetic chiral molecules can induce magnetic states and unconventional superconductivity in a superconductor, a novel mechanism previously associated mainly with magnetic impurities.

Findings

Observation of in-gap YSR-like states shifting with magnetic field.

Evidence of hybridized YSR-like states leading to possible triplet superconductivity.

Transition between magnetic-induced states governed by molecular density.

Abstract

Hybrid ferromagnetic/superconducting systems are well known for hosting intriguing phenomena such as emergent triplet superconductivity at their interfaces and the appearance of in-gap, spin polarized Yu-Shiba-Rusinov (YSR) states bound to magnetic impurities on a superconducting surface. In this work we demonstrate that similar phenomena can be induced on a surface of a conventional superconductor by chemisorbing non-magnetic chiral molecules. Conductance spectra measured on NbSe2 flakes over which chiral alpha helix polyalanine molecules were adsorbed, exhibit, in some cases, in-gap states nearly symmetrically positioned around zero bias that shift with magnetic field, akin to YSR states, as corroborated by theoretical simulations. Other samples show evidence for a collective phenomenon of hybridized YSR-like states giving rise to unconventional, possibly triplet superconductivity, manifested in the conductance spectra by the appearance of a zero bias conductance that diminishes, but does not split, with magnetic field. The transition between these two scenarios appears to be governed by the density of adsorbed molecules.