# Coupled Yu-Shiba-Rusinov states in molecular dimers on NbSe$_2$

## TL;DR

This study demonstrates the creation and analysis of coupled Yu-Shiba-Rusinov states in magnetic molecular dimers on a 2D superconductor, advancing understanding of magnetic impurity effects in superconductivity and potential topological states.

## Contribution

It presents the first controlled creation and experimental observation of coupled YSR states in molecular dimers on NbSe2, supported by theoretical modeling.

## Key findings

- Coupled YSR states observed in CoPc dimers on NbSe2.
- STM manipulation enables precise dimer formation.
- Theoretical models confirm the experimental coupled states.

## Abstract

Magnetic impurities have a dramatic effect on superconductivity by breaking the time-reversal symmetry and inducing so-called Yu-Shiba-Rusinov (YSR) low energy bound states within the superconducting gap. The spatial extent of YSR states is greatly enhanced in 2D systems, which should facilitate the formation of coupled states. Here, we observe YSR states on single cobalt phthalocyanine (CoPC) molecules on a 2D superconductor NbSe$_2$ using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). We use STM lateral manipulation to create controlled CoPc dimers and demonstrate the formation of coupled YSR states. The experimental results are corroborated by theoretical analysis of the coupled states in lattice and continuum models. Our work forms an important step towards the realization of exotic topological states in designer magnetic lattices.