Electronic Properties of Rhombohedral Graphite

This thesis presents the first systematic electron transport investigation of rhombohedral graphite (RG) films and thus lies at the interface of graphene physics, vdW heterostructure devices and topological matter. Electron transport investigation into the rhombohedral phase of graphite was limited to a few layers of graphene due to the competing hexagonal phase being more abundant. This work reports that in exfoliated natural graphite films, rhombohedral domains of up to 50 layers can be found. In the low energy limit, these domains behave as an N-layer generalisation of graphene. Moreover, being a potential alternative to twisted bilayer graphene systems, RG films show a spontaneous metal-insulator transition, with characteristic symmetry properties that could be described by mean-field theory where superconductivity is also predicted in these low energy bands. A nodal-line semimetal in the bulk limit, RG thin films are a 3D generalisation of the simplest topological insulator model:the Su-Schrieffer-Heeger chain. Similar to the more usual topological insulators, RG films exhibit parallel conduction of bulk states, which undergo three-dimensional quantum transport that reflects bulk topology.

Dr. Servet Ozdemir received his initial education in Physics at the University of Warwick, graduating with a Bachelor of Science and a Master of Physics degree in 2016. During his years at Warwick, he also worked at various research groups at University of Cambridge and Bogazici University as well as Warwick. After obtaining his PhD studentship from Graphene NOWNANO Centre of Doctoral Training, he enrolled at University of Manchester to carry out his doctoral studies under the supervision of Nobel laureate Sir Konstantin Novoselov. At Manchester, he played a key role within the team that has carried out the first ever systematic electron transport investigation of rhombohedral graphite films, demonstrating fascinating graphene physics in these films with topological properties. He is currently working as a research associate at the Quantum Photonics Laboratory of Prof. Brian Gerardot at Heriot-Watt University, investigating electronic as well as optical properties of 2D semiconductors.