Kondo effect in quantum dots coupled to ferromagnetic leads

TL;DR

This paper investigates how ferromagnetic leads influence the Kondo effect in quantum dots, revealing unique behaviors in conductance and magnetic field response depending on lead alignment.

Contribution

It provides a detailed analysis of the Kondo effect in quantum dots with ferromagnetic leads, highlighting the impact of lead spin polarization and alignment on the Kondo resonance.

Findings

Parallel alignment leads to a finite-field strong-coupling limit.

Zero-bias anomaly can split without external magnetic field.

Asymmetrical splitting occurs in antiparallel alignment with magnetic field.

Abstract

We study the Kondo effect in a quantum dot which is coupled to ferromagnetic leads and analyse its properties as a function of the spin polarization of the leads. Based on a scaling approach we predict that for parallel alignment of the magnetizations in the leads the strong-coupling limit of the Kondo effect is reached at a finite value of the magnetic field. Using an equation-of-motion technique we study nonlinear transport through the dot. For parallel alignment the zero-bias anomaly may be split even in the absence of an external magnetic field. For antiparallel spin alignment and symmetric coupling, the peak is split only in the presence of a magnetic field, but shows a characteristic asymmetry in amplitude and position.