The Influence of Magnetic Anisotropy on the Kondo Effect and Spin-Polarized Transport through Magnetic Molecules, Adatoms and Quantum Dots

TL;DR

This paper theoretically investigates how magnetic anisotropy and exchange interactions affect the Kondo effect and spin-polarized transport in nanosystems like magnetic molecules, adatoms, and quantum dots, revealing suppression and restoration mechanisms.

Contribution

It provides a detailed analysis of the influence of magnetic anisotropy and exchange coupling on the Kondo effect using numerical renormalization group methods, highlighting new transport behaviors.

Findings

Magnetic anisotropy suppresses the Kondo resonance.

Exchange coupling impacts the formation of the Kondo effect.

External magnetic fields can restore the Kondo resonance.

Abstract

Transport properties in the Kondo regime of a nanosystem displaying uniaxial magnetic anisotropy (such as a magnetic molecule, magnetic adatom or quantum dot coupled to a localized magnetic moment) are analyzed theoretically. In particular, the influence of spin-polarized transport through a local orbital of the system and exchange coupling of conduction electrons to the system's magnetic core on the Kondo effect is discussed. The numerical renormalization group method is applied to calculate the spectral functions and linear conductance in the case of the parallel and antiparallel configurations of the electrodes' magnetic moments. It is shown that both the magnetic anisotropy as well as the exchange coupling between electrons tunneling through the conducting orbital and magnetic core play an important role in formation of the Kondo resonance, leading generally to its suppression. Specific transport properties of such a system appear also as a nontrivial behavior of tunnel magnetoresistance. It is also shown that the Kondo effect can be restored by an external magnetic field in both the parallel and antiparallel magnetic configurations.