Kondo effect in a semiconductor quantum dot coupled to ferromagnetic electrodes

TL;DR

This study demonstrates the manipulation of the Kondo effect in a semiconductor quantum dot coupled to ferromagnetic electrodes, showing how magnetic fields influence the Kondo resonance and revealing an effective magnetic field in the system.

Contribution

First experimental observation of magnetic field tuning of the Kondo effect in a semiconductor quantum dot with ferromagnetic electrodes.

Findings

Kondo resonance splits at N=3 without external field

Applying magnetic field reduces the splitting

Kondo effect nearly restored at B=1.2 T

Abstract

Using a laterally-fabricated quantum-dot (QD) spin-valve device, we experimentally study the Kondo effect in the electron transport through a semiconductor QD with an odd number of electrons (N). In a parallel magnetic configuration of the ferromagnetic electrodes, the Kondo resonance at N = 3 splits clearly without external magnetic fields. With applying magnetic fields (B), the splitting is gradually reduced, and then the Kondo effect is almost restored at B = 1.2 T. This means that, in the Kondo regime, an inverse effective magnetic field of B ~ 1.2 T can be applied to the QD in the parallel magnetic configuration of the ferromagnetic electrodes.