Photoemission spectroscopies and their application in solid state and material physics

Abstract

Understanding the electronic properties of solid state systems is of fundamental importance to all matter. In particular, understanding and tailoring the properties of bound electrons in materials is an indispensable step to broaden our fundamental knowledge in diverse areas, whilst establishing new approaches to design materials with tailored properties. Bound electrons are indeed an essential building block which ensures the existence of a material itself, providing the explanation to the origin of local bondings between atoms and molecules. For this reason, they are an essential ingredient for explaining chemical, physical, thermal, magnetic and vibrational properties of materials.

Photoemission spectroscopy is a powerful and versatile tool, able to elucidate the electronic properties of solid state systems and the behaviour of bound electrons in a solid. Photoemission gives fundamental insight into the microscopic origin of several physics and chemistry phenomena ranging from spin-orbit coupling, electric- and size-driven quantum confinement, crystal field splitting, many-body interactions to surface-catalysis and surface-reactions.

This Thesis is aimed to expand the photoemission toolbox for studying how the interplay of physical dimensionality, many-body effects and spin-orbit coupling influences the quantum many-body ground states of a system and how relevant the choice of a certain material can be for manipulating and reordering the hierarchy of the energy scales by which such effects manifest. In particular, I show how photoemission spectroscopies are used to investigate the electronic properties of carbon-based materials such as graphene and diamond, layered materials such as WSe2 and NbSe2, hybrid systems such as phosphorus delta-layers in silicon and boron delta-layers in diamond, intermediate band materials such as Cr-doped ZnS and the catalytic activity of metal surfaces in contact with organic molecules.

My final goal is to provide a multifaceted approach for (1) studying, tuning and ultimately controlling the electronic properties of quantum materials for quantum device applications, (2) expanding our fundamental knowledge in solid state physics, (3) contributing to other fields of research and finally (4) expanding the photoemission toolbox to study materials with unconventional properties.