Kondo effect in a semiconductor quantum dot coupled to ferromagnetic electrodes

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 similar to 1.2 T can be applied to the QD in the parallel magnetic configuration of the ferromagnetic electrodes. (c) 2007 American Institute of Physics.