9404421 Jona Technical abstract: Epitaxial and pseudomorphic ultrathin (5 to 10 layers) films of (mostly magnetic) metals grown on suitable substrates will be studied with quantitative low energy electron diffraction (LEED). The goals are: (1) to establish the conditions for successful growth; (2) to determine the atomic structure of the bulk and of the surface of the films; and (3) to determine the strains and the equilibrium phase of the films. Some of the immediate projects are: stabilization of metastable phases (e.g. face center cubic cobalt, face center and body center manganese, etc.); growth and characterization of shear-strained iltrathin films; and expitaxy of metals (particularly magnetic metals) on semiconductors. Interaction with theorists doing first- principle total-energy calculations of both equilibrium and pseudomorphic phases will be pursued. Non-technical abstract: For a number of electronic, magnetic and optical applications, modern technology requires the use of thinner crystalline films, some only five to ten atomic layers thick. In order to understand the properties of these ultrathin films, the first piece of information that one seeks is the atomic structure, i.e. the arrangement of the atoms on the surface and in the interior of the films. The present project has three main goals: (1) to establish procedures for preparing ultrathin films of scientifically and technologically interesting materials; (2) to determine the atomic structure of the surface and of the interior of the films; and (3) to determine the state of strains in the films. Many chemical and physical properties of ultrathin films depend on the atomic structure and the strains, and it is expected that this project could lead to the production of films with novel and useful properties for electronic and magnetic applications. ***
