Microscopic resolution of the interplay of Kondo screening and superconducting pairing: Mn-phthalocyanine molecules adsorbed on superconducting Pb(111)

TL;DR

This study investigates how magnetic Mn-phthalocyanine molecules on superconducting Pb(111) surfaces exhibit a complex interplay between Kondo screening and superconducting pairing, revealing the dominant role of hybridization strength.

Contribution

It combines experimental scanning tunneling spectroscopy with theoretical scaling and numerical renormalization group calculations to elucidate the interplay between Kondo effect and superconductivity in a specific molecular system.

Findings

Identification of two Kondo screening channels in the system.

Universal and non-universal behaviors captured by an effective one-channel Anderson model.

Hybridization strength determines the relation between Kondo screening and superconducting pairing.

Abstract

Magnetic molecules adsorbed on a superconductor give rise to a local competition of Cooper pair and Kondo singlet formation inducing subgap bound states. For Manganese-phthalocyanine molecules on a Pb(111) substrate, scanning tunneling spectroscopy resolves pairs of subgap bound states and two Kondo screening channels. We show in a combined approach of scaling and numerical renormalization group calculations that the intriguing relation between Kondo screening and superconducting pairing is solely determined by the hybridization strength with the substrate. We demonstrate that an effective one-channel Anderson impurity model with a sizable particle-hole asymmetry captures universal and non-universal observations in the system quantitatively. The model parameters and disentanglement of the two screening channels are elucidated by scaling arguments.