Structural, magnetic and electronic properties of surface alloys and interfaces : a first principles study

Abstract

The broad aim of this thesis is to study different classes of two-dimensional (2D) materials using first-principles methods. Surfaces and 2D systems are interesting for a large number of reasons. Atoms at the surface have reduced coordination with respect to the bulk, which is responsible for several unusual phenomena observed only at the surface. Some of these include structural relaxations and/or reconstructions, mixing of bulk-immiscible metals, enhanced chemical reactivity, high magnetic anisotropy and exotic magnetic phases such as spin spirals. In this work, I have mainly focused on metallic surface alloys and interfaces, with a common theme being magnetic materials. We would like to understand various interactions which are dominant at surfaces and interfaces, and how the interplay between them can lead to interesting structural, magnetic and electronic properties. Some of the interactions which are dealt with include elastic, chemical, and magnetic interactions. This study has allowed us not only to gain insight into the relative importance of these interactions, but also to use our understanding to formulate design principles. Using these principles as a guideline, we have, e.g., designed a novel surface alloy. In most of my projects, I have worked alongside an experimental group, and have seen a great synergy between my theoretical studies and experimental investigations.