Chapter 3 - Thin Epitaxial Films: Insights from Theory and Experiment

Abstract

Publisher Summary This chapter discusses metastability and pseudomorphic growth, kinetics, strain in hetero-epitaxial growth, alloy phase diagrams and defects, metastability and Bain distortions, and interfaces in metallic multilayers—Pb–Nb and Ag–Nb. A suitable free energy, when monitored as a function of various parameters such as lattice parameters, temperature or pressure is a complicated function of many variables with possibly numerous local minima. Metastability that is discussed in this chapter has to do with the existence of such local minima. To crossover from one local minimum to a neighboring minimum, the system needs to overcome an energy barrier. Growth conditions clearly play a vital role in determining the resulting metastable phase. Transition metals provide a platform for studying metastable phases. A layer by layer, pseudomorphic growth (that is, in registry with the substrate) usually provides insight into numerous size, surface and interface dependent properties of metastable structures. Kinetic processes do not necessarily select the most stable, lowest energy state but the most easily (kinetically) accessible state. It is seen that surface diffusion and migration of atoms can play complicated roles in the kinetics of growth. Thin epitaxial films are known to exhibit a wide variety of fascinating fundamental properties because of the interplay of electronic structure, morphology, strain, and magnetism. Idealized, simple systems are highly desirable. A great deal of attention has been paid to Fe films grown on various metallic substrates, such as Fe/Cu, Fe/W and Fe/Mo. One major reason for this interest is the magnetism associated with Fe films, which may depend on the growth mechanism. There are details of Magnetic 3d metals, Epitaxially grown magnetic systems, epitaxially grown fcc Fe/Cu and Fe 16 N 2 films— experimental background: Fe nitrides, discussion of large Fe moments, Fe/Cr, and bcc Nickel grown on Fe and GaAs.