ELECTRONIC-STRUCTURE, MAGNETISM AND GROWTH OF ULTRATHIN FILMS OF TRANSITION-METALS

The conditions which determine the growth mode (Frank-van der Merwe, Stranski-Krastanov, Volmer-Weber) on a perfect surface are obtained in terms of the electronic structure of ultrathin films and interfaces. The various contributions (elastic, structural, chemical, magnetic, etc.) to the spreading energy and to the interface energy are obtained at zero Kelvin for overlayers of a transition metal A on a transition metal B. We use a tight-binding model and the recursion method to get general trends for all transition metal pairs (A, B) but the electronic structure derived from this simple model agrees when available with the ab-initio (LSDA) calculations. The spreading energy results from a delicate balance between its contributions but the wetting of the substrate by a monolayer (gamma-1 < 0) is generally obtained when the thermodynamical criterion gamma-A < gamma-B is satisfied. Finally the stability of an overlayer with respect to the formation of two-dimensional ordered compounds is investigated.