Interplay of the Kondo Effect and Spin-Polarized Transport in Magnetic Molecules, Adatoms and Quantum Dots

We study the interplay of the Kondo effect and spin-polarized tunneling in a class of systems exhibiting uniaxial magnetic anisotropy, such as magnetic molecules, magnetic adatoms, or quantum dots coupled to a single localized magnetic moment. Using the numerical renormalization group method we calculate the spectral functions and linear conductance in the Kondo regime. We show that the exchange coupling between conducting electrons and localized magnetic core generally leads to suppression of the Kondo effect. We also predict a nontrivial dependence of the tunnel magnetoresistance on the strength of exchange coupling and on the anisotropy constant.