Quantum transport in carbon-based nanostructures
Dr. rer. nat. (equiv. PhD) Thesis, University of Regensburg, July 2007
The electronic structure and the quantum transport properties of graphene, carbon nanotubes and graphene nanoribbons are studied using analytical and numerical tools. Special care is taken in considering fundamental questions of high experimental relevance and in relating the results to experiments.
The main focus of the work is on numerical calculations based on the tight-binding description of electrons, also integrating the results of microscopic ab initio calculations and including several minimal models at various degrees of detail.
Transport calculations are done based on the Landauer formalism of linear conductance, using Green function decimation algorithms for the efficient handling of large systems of up to thousands of atoms.
Following three detailed theoretical introductory chapters, the work is organized in four parts: One chapter on the effects of realistically modelled metallic contacts on the transport properties of nanotubes and -ribbons, including a section dealing with ballistic magnetoresistance effects. Another chapter about the mesoscopic length scales in disordered and defective carbon systems. A chapter on multilayer carbon systems that deals with issues of approximate momentum conservation in incommensurate systems. Finally, a chapter on the effects of external magnetic fields on the electronic structure of carbon systems.
The appendices give a precise derivation of the theoretical tools used in the work and include fully documented source code implementations of the relevant algorithms used throughout the project.