Fano resonance in a normal metal/ferromagnet-quantum dot-superconductor device

TL;DR

This paper provides a theoretical analysis of how the interplay between Kondo resonance and Andreev bound states influences Andreev transport in a quantum dot device coupled with a normal/ferromagnetic metal and a superconductor, revealing Fano resonance effects.

Contribution

It uncovers how the interference between Kondo resonance and ABSs modifies the lineshape, and how spin-polarization and magnetic fields can tune this interaction.

Findings

Kondo resonance lineshape is significantly affected by interference with ABSs.

Spin-polarization induces splitting of Kondo resonance and ABSs.

Magnetic fields provide a tuning mechanism for the resonance lineshape.

Abstract

We investigate theoretically the Andreev transport through a quantum dot strongly coupled with a normal metal/ferromagnet and a superconductor (N/F-QD-S), in which the interplay between the Kondo resonance and the Andreev bound states (ABSs) has not been clearly clarified yet. Here we show that the interference between the Kondo resonance and the ABSs modifies seriously the lineshape of the Kondo resonance, which manifests as a Fano resonance. The ferromagnetic lead with spin-polarization induces an effective field, which leads to splitting both of the Kondo resonance and the ABSs. The spin-polarization together with the magnetic field applied provides an alternative way to tune the lineshape of the Kondo resonances, which is dependent of the relative positions of the Kondo resonance and of the ABSs. These results indicate that the interplay between the Kondo resonance and the ABSs can significantly affect the Andreev transport, which could be tested by experiments.