Quantum Dots Attached to Ferromagnetic Leads: Exchange Field, Spin Precession, and Kondo Effect

TL;DR

This paper investigates how a quantum dot connected to ferromagnetic leads exhibits spin-dependent transport phenomena, including exchange fields, spin precession, and the Kondo effect, influenced by Coulomb interactions.

Contribution

It provides a comprehensive analysis of the interplay between spin polarization, Coulomb interaction, and quantum dot transport, highlighting the emergence of exchange fields and their effects.

Findings

Exchange field causes spin precession in the quantum dot.

Transport regimes show level splitting due to the exchange field.

Analysis of the Kondo effect in the presence of ferromagnetic leads.

Abstract

Spintronics devices rely on spin-dependent transport behavior evoked by the presence of spin-polarized electrons. Transport through nanostructures, on the other hand, is dominated by strong Coulomb interaction. We study a model system in the intersection of both fields, a quantum dot attached to ferromagnetic leads. The combination of spin-polarization in the leads and strong Coulomb interaction in the quantum dot gives rise to an exchange field acting on electron spins in the dot. Depending on the parameter regime, this exchange field is visible in the transport either via a precession of an accumulated dot spin or via an induced level splitting. We review the situation for various transport regimes, and discuss two of them in more detail.