Thesis presented October 26, 2012

Abstract:
Rapidly changing market of electronic devices sets up a lot of challenges for the manufacturing and design technologies. When electronic circuit elements get smaller, the device behavior becomes increasingly complicated as new physical phenomena due to quantum interference effects come into play. Understanding of the latter necessitates development of advanced theoretical tools. In this thesis we investigate quantum electron transport in multiterminal devices. In the first part making use of the Keldysh Green's functions we develop a general framework for electron quantum transport in multi-terminal systems in the presence of oscillating fields. We are able to express any AC observable in terms of stationary Green's functions and leads self-energies, which makes our formalism a practical numerical tool for a variety of possible finite-frequency perturbations. In the second part we investigate theoretically a proposal to induce strong spin-orbital coupling in graphene by functionalizing its surface with certain type of heavy ad atoms. In this case graphene becomes a topological insulator. Then we investigate the evolution of this topological phase in external magnetic field. We were able to see a unique transition between quantum Hall and quantum spin Hall phases in the same system by only varying the position of the Fermi level. A heterojunction between these two phases was shown to give rise to a new type of a chiral state at the interface between the latter.

Keywords:
Finite frequency, Spin-orbit coupling, Hall effects, Quantum transport

On-line thesis.