Compensation of the Kondo effect in quantum dots coupled to ferromagnetic leads withinthe equation of motion approach

Abstract

We propose a new approximation scheme within the equation of motion approach (EOM)to spin polarized transport through a quantum dot coupled to ferromagneticleads. It has some advantages over a standard EOM technique widely used inthe literature, in particular when we are interested in spin polarized quantities.Namely, it gives values of the dot spin polarization which are closer to the onesobtained within the numerical renormalization group (NRG) than the standardEOM approach. While restoring the Kondo effect, the spin polarization vanishesand the transport becomes unpolarized, in agreement with NRG and real timediagrammatic calculations. The standard EOM procedure gives non-zero values of the spinpolarization, and the transport is still spin polarized. Both approximations give the samecorrect splitting of the Kondo peaks due to ferromagnetism in the electrodes.