Interference effects induced by Andreev bound states in a hybrid nanostructure composed by a quantum dot coupled to ferromagnetic and superconductor leads

TL;DR

This paper investigates interference effects caused by Andreev bound states in a quantum dot hybrid nanostructure with ferromagnetic and superconducting leads, revealing how electron-hole correlations influence transport properties.

Contribution

It introduces a detailed analysis of interference effects and resonance phenomena in a quantum dot system coupled to ferromagnetic and superconducting leads, considering spin-flip and proximity effects.

Findings

Resonance in transmittance depends on magnetization orientation.

Electron-hole correlations induce a resonance replacing the dip.

Interference effects are observable in electrical current under bias.

Abstract

In this work, it is considered a nanostructure composed by a quantum dot coupled to two ferromagnets and a superconductor. The transport properties of this system are studied within a generalized mean-field approximation taking into account proximity effects and spin-flip correlations within the quantum dot. It is shown that the zero-bias transmittance for the co-tunneling between the ferromagnetic leads presents a dip whose height depends on the relative orientation of the magnetizations. When the superconductor is coupled to the system, electron-hole correlations between different spin states leads to a resonance in the place of the dip appearing in the transmittance. Such an effect is accompanied by two anti-resonances explained by a leakage of conduction channels from the co-tunneling to the Andreev transport. In the non-equilibrium regime, correlations within the quantum dot introduce a dependence of the resonance condition on the finite bias applied to the ferromagnetic leads. However, it is still possible to observe signatures of the same interference effect in the electrical current.