Axion term in topological insulators with broken time reversal and parity
department or school: Science, Faculty of
department or school: Physics and Astronomy, Department of
data provider: DSpace
degree campus: UBCV
creator: Reis, Itamar
issued: 2014-04-10T16:17:05Z
issued: 2014
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: The main subject of this work is the axion term in the effective electromagnetic action of topological insulators, which is responsible for the special electromagnetic properties of these materials. The axion term is characterized by a parameter θ, which can only take the values of 0, for regular insulators, or π, for topological insulators, respecting at least one of the time reversal or parity symmetries. A non zero axion term leads to a variety of measurable phenomena, generally referred to as the magneto-electric effects. We focus our interest on the value the parameter θ takes for a topological insulator, when both time reversal and parity are broken. In this case θ no longer must be quantized to 0 or π. We use a lattice model for a topological insulator, and introduce a symmetry breaking term in the Hamiltonian. We numerically find the value of θ in this case using calculations of the magnitude of various magneto-electric effects. The results are compared to the theoretical prediction. We find that θ is no longer quantized when a specific symmetry breaking term is introduced.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/46360
note: Axion term in topological insulators with brokentime reversal and paritybyItamar ReisB.Sc, University of Tel-Aviv, 2010a thesis submitted in partial fulfillmentof the requirements for the degree ofMaster of Scienceinthe faculty of graduate and postdoctoralstudies(Physics)The University Of British Columbia(Vancouver)March 2014c© Itamar Reis, 2014AbstractThe main subject of this work is the axion term in the effective electromag-netic action of topological insulators, which is responsible for the specialelectromagnetic properties of these materials. The axion term is charac-terized by a parameter θ, which can only take the values of 0, for regularinsulators, or pi, for topological insulators, respecting at least one of the timereversal or parity symmetries. A non zero axion term leads to a variety ofmeasurable phenomena, generally referred to as the magneto-electric effects.We focus our interest on the value the parameter θ takes for a topologicalinsulator, when both time reversal and parity are broken. In this case θ nolonger must be quantized to 0 or pi. We use a lattice model for a topologicalinsulator, and introduce a symmetry breaking term in the Hamiltonian.We numerically find the value of θ in this case using calculations of themagnitude of various magneto-electric effects. The results are compared tothe theoretical prediction. We find that θ is no longer quantized when aspecific symmetry breaking term is introduced.iiPrefaceThis dissertation is unpublished work, ultimately based on results from anumerical calculation. These results are compared with known theoreticalpredictions. The code for the calculation was written by the author, I. Reis.The diagrammatic theoretical calculation found in chapter 2 was carried outby my supervisor M. Franz.iiiTable of ContentsAbstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iiPreface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iiiTable of Contents . . . . . . . . . . . . . . . . .…
has type: Thesis/Dissertation
date issued: 2014-05
is shown at: 10.14288/1.0166899
language: eng
degree discipline: Physics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivs 2.5 Canada
rights URI: http://creativecommons.org/licenses/by-nc-nd/2.5/ca/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/46360