Density functional theory based strategies for tailoring the magnetic and morphological properties of surfaces

Abstract

For the last few decades materials science has been the at the frontier of technological development. Today’s computer age requires the development of efficient and “smart” materials to gain faster and quicker control over data processing and probing. This drive is further fueled by the demand for developing novel materials that permit ever-increasing storage density. The broad aim of this thesis is to understand and tailor the physics and chemistry of technologically important materials using first principles methods, particularly in the areas of information storage and semiconductor electronics. In this context, we have tried to develop strategies to (1) control the magnetic properties of metal surfaces to obtain new magnetic ordering, and (2) tune the chemical properties of semiconductor surfaces to obtain new surface morphologies. While magnetic metal surfaces are potential candidates for spintronics applications, semiconductor surfaces are already used for electronics applications, e.g., for the fabrication of integrated circuit chips. In this thesis, we have primarily used density functional theory (DFT) to study the ground state properties of systems. Such properties include the relative stability of different phases, formation energy, surface stress, magnetic anisotropy energy, adsorption and co-adsorption energies, energy barriers, etc. Moreover, the results from DFT are used as inputs in order to calculate (a) the activation barriers for the minimum energy path for a (complex) chemical reaction using the nudged elastic band (NEB) method, and (b) the Gibbs free energy of a system at finite temperature and pressure using the ab initio atomistic thermodynamics (AIAT) method. These methods are briefly discussed in Chapter