Elastic adsorbate interactions at the mesoscale

R C Longo, V S Stepanyuk, J Kirschner
2006 Journal of Physics: Condensed Matter  
We show that elastic interactions between adatoms and small islands on a surface exhibit a novel intermediate-ranged oscillatory behaviour. Taking small Fe islands on Cu(111) as an example, we perform atomic-scale simulations and reveal that elastic interactions strongly depend on the size of the islands. Stress variation on the atomic scale is found to be the driving force for the size effect in elastic interactions. The understanding of interactions between adatoms and clusters on surfaces is
more » ... a topic of fundamental interest for the fast-growing area of nanoscience. With shrinking size of nanostructures, which may approach atomic distances, the control of interactions between individual atoms becomes crucial. At small adatom separations direct electronic interactions dominate, but for intermediate and large adatom-adatom distances, substrate-mediated electronic and elastic interactions prevail [1] . Recent experiments [2, 3] and ab initio calculations [4] have resolved the long-range oscillatory electronic interaction between adatoms caused by the quantum interference of surface-state electrons. It has been found that adatoms may attract or repel each other, depending on the separation. Electronic interactions between adatoms and small clusters at intermediate distances have also been found to strongly affect growth processes [4] [5] [6] . The classical works of Lau and Kohn [7] , and Marchenko and Parshin [8] , predicted that the elastic interaction between identical adatoms on isotropic surfaces should be repulsive, with energy varying with distance as d −3 . Anisotropy of the substrate can lead to attraction between like adatoms [9, 10]. Recent advances in nanoscale fabrication, self-assembly and self-organization [11] of nanostructures have created renewed interest in the substrate-mediated elastic interactions between nanostructures. For example, the importance of elastic interactions for the nucleation of islands in submonolayer epitaxy has been demonstrated by means of a Monte Carlo simulation [12] . Rickman and Srolovitz [13] have found that the interaction energy between circular islands on an isotropic surface is repulsive. Recent work of Peyla et al [14] has shown that elastic interactions between defects in thin layers may be either attractive
doi:10.1088/0953-8984/18/40/001 fatcat:le72iio7ufhxnkdnkhamppj57m