  The state of the art ab initio calculations of quantum mirages,the
spin-polarization of surface-state electrons and the exchange interaction
between magnetic adatoms in Cu and Co corrals on Cu(111) are presented. We find
that the spin-polarization of the surface-state electrons caused by magnetic
adatoms can be projected to a remote location and can be strongly enhanced in
corrals compared to an open surface.Our studies give a clear evidence that
quantum corrals could permit to tailor the exchange interaction between
magnetic adatoms at large separations. The spin-polarization of surface-state
electrons at the empty focus in the Co corral used in the experimental setup of
Manoharan et al., (Nature 403, 512 (2000)) is revealed.
