This program will explore the structure and electronic properties of transition metals in non-equilibrium crystal structures. These metastable structures will be produced in the form of ultra-thin films using atomic layer epitaxial growth techniques. Some of the metal film crystals are metastable because they adopt a crystal structure through epitaxy which is not the preferred structure at room-temperature. Other structures found in epitaxial growth are completely new, and exist only as films stabilized by the choice of an appropriate substrate template. One of the first unique metastable metal stuctures was BCC cobalt, grown as film on a semiconductor substrate. BCC cobalt does not exist as a stable bulk phase. Metastable film structures and growth modes will be studied by a combination of techniques which will probe both long-range and short-range order in the films. These techniques include electron diffraction and angle-resolved x-ray photoelectron diffraction (ARXPD). The ARXPD technique has unique characteristics, such as elemental specificity, which will allow them to unambiguously identify the presence of new metastable film structures. Electronic properties of this new class of materiasl will be studied using angle-resolved photoemission spectroscopy with synchrotron radiation.
