We present a novel approach to spin manipulation in atomic-scale
nanostructures. Our ab initio calculations clearly demonstrate that it is
possible to tune magnetic properties of sub-nanometer structures by adjusting
the geometry of the system. By the example of two surface-based systems we
demonstrate that (i) the magnetic moment of a single adatom coupled to a buried
magnetic Co layer can be stabilized in either a ferromagnetic or an
antiferromagnetic configuration depending on the spacer thickness. It is found
that a buried Co layer has a profound effect on the exchange interaction
between two magnetic impurities on the surface. (ii) The exchange interaction
between magnetic adatoms can be manipulated by introducing artificial
nonmagnetic Cu chains to link them.Comment: 4 pages, submitted to PR