Elastic relaxations in ultrathin epitaxial alloy films

Elastic interactions responsible for the stability of nanometer-scale patterns in ultrathin, bulk immiscible-alloy films were analyzed using a hybrid atomistic-continuum model. A continuum elastic theory describing a deformable substrate and a rigid substrate atomistic scheme, were discussed as limiting cases on long and short length scales, respectively, in order to explain the alloy film behavior. Results for the Co-Ag surface alloy on Ru(0001), where nanoscale pattern formation was observed, showed that relaxations dominated the energitics within the surface layer, while the substrate relaxation contributed a very small amount to the total formation energies of stable nanostructures.