Hydrodynamics and Plasmonics in Low-dimensional Systems

Abstract

The primary theme of this thesis concerns the behaviour of collective plasmonic oscillations within electron fluids in low-dimensional systems. Such phenomena occur within metallic conductive media as both bulk plasmons, which are longitudinal charge density waves that interact with the ionic cores of the metal, and surface plasmons, which form from the coupling between bulk plasmons near the surface of the metal and incident photonic radiation. On the other hand, considering the position of this thesis within the modern field of theoretical condensed matter physics, its secondary theme is that of the topological symmetry protection of localised edge states. This thesis therefore explores a few systems in which surface plasmon modes are predicted to be topologically symmetry protected. In each case, the symmetry protection applies in one-dimension thereby requiring the presence of certain prerequisite discrete symmetries. However, the overall system need not necessarily be one-dimensional. Indeed, the overall systems are always fundamentally three-dimensional with reductions in dimension occurring as a result of the specifics of the problem and the analysis of the topological protection. Some of the key results of this undertaking, which form the primary findings of Chapters 3 ,4, and 5, are that: the non-Hermitian effect of edge polarisation occurs in Hermitian systems; topological plasmonic waveguides can be formed from a triharmonic metal-dielectric grating, which may be readily modified to include graphene instead of the metal; the two-dimensional surface of a three-dimensional topological insulator can behave as a plasmonic waveguide in the presence of a spatially-varying Hall conductivity. In all of these chapters, established theoretical methods are used and extended to analyse these systems in novel ways. Such methods are introduced and discussed within the introductory chapters (Chapters 1 and 2) in order to acquaint the reader with the necessary background knowledge, after which the original content of the work proceeds.

Date of Award	31 Dec 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Vladimir Falko (Supervisor)