Nonlocal pairing as a source of spin exchange and Kondo screening

We show that the Kondo screening in a correlated double-quantum-dot structure may be caused solely by the proximity of a superconductor which induces nonlocal pairing by Andreev reflection processes. This leads to an effective exchange interaction, which we estimate perturbatively, and we corroborate the analytical predictions by the numerical renormalization group calculations, using an effective model for the superconductor-proximized nanostructure. We determine the dependence of the relevant Kondo temperature on the coupling to the superconductor and predict a characteristic modification of conventional low-temperature transport behavior, which can be used to experimentally distinguish this phenomenon from other Kondo effects. The occurrence of nonlocal pairing exchange does not depend on the details of the proposed setup; therefore, it can also be relevant for the bulk materials, such as heavy-fermion compounds.