Kondo resonance of a Co atom exchange coupled to a ferromagnetic tip
  The Kondo effect of a Co atom on Cu(100) was investigated with a low-temperature scanning tunneling microscope using a monoatomically sharp nickel tip. Upon a tip-Co contact, the differential conductance spectra exhibit a spin-split asymmetric Kondo resonance. The computed ab initio value of the exchange coupling is too small to suppress the Kondo effect, but sufficiently large to produce the splitting observed. A quantitative analysis of the line shape using the numerical renormalization group technique indicates that the junction spin polarization is weak. 
D.-J. Choi, S. Guissart, M. Ormaza, N. Bachellier, O. Bengone, P.   Simon, and L. Limot
cond-mat.mes-hall cond-mat.str-el