Majorana bound states on a periodic superconducting vortex lattice
department or school: Science, Faculty of
department or school: Physics and Astronomy, Department of
data provider: DSpace
degree campus: UBCV
creator: Pathak, Vedangi
issued: 2020-08-27T21:23:59Z
issued: 2020
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: Majorana quasi-particles can exist as zero-energy excitations bound to vortices present on the surface of a topological insulator that is proximity-coupled to a type-II superconductor. Such a system finds its natural realisation on the surface of the iron-based superconductor FeTe₀.₅₅Se₀.₄₅ which has been identified as a potential topological superconductor and is expected to host Majorana quasi-particles as zero-energy excitations on vortices. This thesis aims to explain the occurrence of Majorana vortex bound states present on such materials by constructing a model for a vortex lattice on periodic manifolds. A two-dimensional square lattice model is developed to capture the low energy physics of the surface states of a topological insulator proximity-coupled to an s-wave superconductor. Using the Franz-Tesanovic singular gauge transformation, multiple vortices can be incorporated in the system by circumventing the problem of branch cuts. To construct finite vortex lattice on periodic manifolds (torus in two dimensions), we need to account for the fluxes through the non-contractible loops of the torus, leading to certain correction terms appearing in the singular gauge transformation. This thesis provides the details of the construction of vortex lattice on a periodic manifold on the surface of topological insulator proximity-coupled to a superconductor and investigates the Majorana zero modes present on the vortices. The theory developed for periodic vortex lattice on the topological insulator-superconductor heterostructure is successful in replicating the experimental observations of Majorana vortex bound states on the surface of the iron-based superconductor FeTe₀.₅₅Se₀.₄₅.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/75727
note: Majorana bound states on a periodic superconductingvortex latticebyVedangi PathakM.Sc., Birla Institute of Technology and Science, Pilani - Goa, India, 2018B.E., Birla Institute of Technology and Science, Pilani - Goa, India, 2018A THESIS SUBMITTED IN PARTIAL FULFILMENT OFTHE REQUIREMENTS FOR THE DEGREE OFMaster of ScienceinThe Faculty of Graduate and Postdoctoral Studies(Physics)The University of British Columbia(Vancouver)August 2020c© Vedangi Pathak 2020The following individuals certify that they have read, and recommend to theFaculty of Graduate and Postdoctoral Studies for acceptance, the thesis entitled:Majorana bound states on a periodic superconducting vortex latticesubmitted by Vedangi Pathak in partial fulfillment of the requirements for thedegree of Master of Science in Physics.Examining Committee:Marcel Franz, Physics and AstronomySupervisorRobert Raussendorf, Physics and AstronomyExamining Committee MemberiiAbstractMajorana quasi-particles can exist as zero-energy excitations bound to vorticespresent on the surface of a topological insulator that is proximity-coupled to atype-II superconductor. Such a system finds its natural realisation on the sur-face of the iron-based superconductor FeTe0.55Se0.45 which has been identifiedas a potential topological superconductor and is expected to host Majorana quasi-particles as zero-energy excitations on vortices. This thesis aims to explain the oc-currence of Majorana vortex bound states present on such materials by construct-ing a model for a vortex lattice on periodic manifolds. A two-dimensional squarelattice model is developed to capture the low energy physics of the surface states ofa topological insulator proximity-coupled to an s-wave superconductor. Using theFranz-Tesˇanovic´ singular gauge transformation, multiple vortices can be incorpo-rated in the system by circumventing the problem of branch cuts. To construct fi-nite vortex lattice on periodic manifolds (torus in two dimensions), we need to ac-count…
has type: Thesis/Dissertation
date issued: 2020-11
is shown at: 10.14288/1.0394063
language: eng
degree discipline: Physics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/75727