Kondo effect with non collinear polarized leads: a numerical   renormalization group analysis
  The Kondo effect in quantum dots attached to ferromagnetic leads with general polarization directions is studied combining poor man scaling and Wilson's numerical renormalization group methods. We show that polarized electrodes will lead in general to a splitting of the Kondo resonance in the quantum dot density of states except for a small range of angles close to the antiparallel case. We also show that an external magnetic field is able to compensate this splitting and restore the unitary limit. Finally, we study the electronic transport through the device in various limiting cases. 
P. Simon, P.S. Cornaglia, D. Feinberg, and C.A. Balseiro