Transverse-electric surface plasmon polaritons in homogeneous and periodic graphene systems

A topological insulator is an extraordinary material; it acts as an electrical bulk insulator that allows an electrical current flow along its surface. The surface current is topologically protected from a defect or scatterer [1]. The idea of topological insulator can be applied not only for electrons but also can be applied for photons, plasmons and phonons. For example, a photonic topological insulator made of photonic crystals or metamaterials has no bulk photon mode but allows for photonic edge modes at the interfaces with other types of photonic topological insulators [2]. Recently, topologically protected (TP) magnetoplasmons in 2D system were proposed theoretically [3] and a graphene film with a hexagonal array of air holes was shown to have TP plasmonic modes at the infrared wavelengths [4].
Project aims: The aim of the project is to theoretically and numerically study topological states in 2D electron gas with additional confinement with modulation of structures. Firstly, the dispersion, Chern numbers of plasmon modes in 2D electron gas will be studied theoretically. Secondly, topological properties (one-way edge modes) in 2D electron gas with periodic modulations, e.g. a patterned graphene film will be investigated using numerical simulations. Finally, with the help of the numerical method, the interaction between TP plasmons with quasi-particles such as phonons and excitons will be explored.
Methods: The project will involve the implementation of finite-element-method (FEM) approach based on classical description of plasmonic response in 2D materials, the application of resonant-state expansion (RSE) method and the development of quantum mechanical tight-binding model.
Scientific Excellence: The outcomes of the project will be extremely useful in understanding the complex mechanism of plasmon excitation in patterned 2D nanostructures. The project requires good understanding on condensed matter theory and electromagnetism and good skills of numerical analysis.
Feasibility of completion within 3.5years: The project is divided into three stages, 1) literature review and definition of problem (0.5 year) 2) modelling/implementation (1.5-2 years) and 3) extending the model to quasi-particle interaction problem (1 year).