Out-of-equilibrium Kondo Effect in a Quantum Dot: Interplay of Magnetic Field and Spin Accumulation

TL;DR

This paper theoretically investigates how spin-polarized currents and magnetic fields influence the Kondo effect in quantum dots, revealing mechanisms to control spin states for nanoelectronic applications.

Contribution

It introduces a self-consistent renormalized approach to analyze nonequilibrium Kondo phenomena under magnetic fields and spin injection, explaining experimental observations.

Findings

Spin-polarized current modulates Zeeman splitting of the Kondo peak.

Spin accumulation can restore the Kondo peak by compensating magnetic field effects.

Unpolarized current shifts both Zeeman-split peaks equally without changing splitting.

Abstract

We present a theoretical study of low temperature nonequilibrium transport through an interacting quantum dot in the presence of Zeeman magnetic field and current injection into one of its leads. By using a self-consistent renormalized equation of motion approach, we show that the injection of a spin-polarized current leads to a modulation of the Zeeman splitting of the Kondo peak in the differential conductance. We find that an appropriate amount of spin accumulation in the lead can restore the Kondo peak by compensating the splitting due to magnetic field. By contrast when the injected current is spin-unpolarized, we establish that both Zeeman-split Kondo peaks are equally shifted and the splitting remains unchanged. Our results quantitatively explain the experimental findings reported in KOBAYASHI T. et al., Phys. Rev. Lett. 104, 036804 (2010). These features could be nicely exploited for the control and manipulation of spin in nanoelectronic and spintronic devices.