Non-equilibrium spin-current detection with a single Kondo impurity

TL;DR

This paper theoretically investigates how a Kondo impurity connected to ferromagnetic leads can detect non-equilibrium spin currents by analyzing the effects of exchange fields and their compensation, restoring Kondo resonance.

Contribution

It introduces a method to use a Kondo impurity as a sensitive sensor for non-equilibrium spin phenomena by controlling spin-dependent chemical potentials.

Findings

Exchange field from ferromagnetic contacts destroys Kondo correlations.

Properly tuned spin-dependent chemical potentials can restore the Kondo resonance.

Kondo impurity acts as a sensitive detector for non-equilibrium spin currents.

Abstract

We present a theoretical study based on the Anderson model of the transport properties of a Kondo impurity (atom or quantum dot) connected to ferromagnetic leads, which can sustain a non-equilibrium spin current. We analyze the case where the spin current is injected by an external source and when it is generated by the voltage bias. Due to the presence of ferromagnetic contacts, a static exchange field is produced that eventually destroys the Kondo correlations. We find that such a field can be compensated by an appropriated combination of the spin-dependent chemical potentials leading to the restoration of the Kondo resonance. In this respect, a Kondo impurity may be regarded as a very sensitive sensor for non-equilibrium spin phenomena.