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Modelling of Berry phase and Fermi-level topologies for emergent quantum phenomena prediction in selected solid state systems
Topological materials host electronic states that remain robust against perturbations and offer routes to novel quantum functions. This thesis investigates three representative compounds - SrSi2, CoSi, and NbP - to reveal how external stimuli, namely tensile strain and electric fields, tune their el...
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| Format: | Thesis |
| Language: | English English |
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Department of Physics
2026
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| _version_ | 1867613153926316032 |
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| access_status_str | Open Access |
| author | Tematio, Gaël-Pacôme Nguimeya |
| author2 | Salagaram, Trisha |
| author_browse | Salagaram, Trisha Tematio, Gaël-Pacôme Nguimeya |
| author_facet | Salagaram, Trisha Tematio, Gaël-Pacôme Nguimeya |
| author_sort | Tematio, Gaël-Pacôme Nguimeya |
| collection | Thesis |
| description | Topological materials host electronic states that remain robust against perturbations and offer routes to novel quantum functions. This thesis investigates three representative compounds - SrSi2, CoSi, and NbP - to reveal how external stimuli, namely tensile strain and electric fields, tune their electronic bands and topological traits. By combining first-principles calculations with model Hamiltonian experiments, we aim to uncover mechanisms behind quantum phase transitions (QPTs) and to establish design principles for materials with tailored quantum states. We perform density functional theory (DFT) calculations within the plane-wave pseudopotential framework using the Quantum ESPRESSO (QE) suite. Spin-orbit coupling (SOC) is included to capture relativistic effects critical for topological properties. We generate maximally localized Wannier functions (MLWFs) with Wannier90 and construct tight-binding (TB) models to compute Berry curvature, surface state spectra, and Fermi arc patterns via WannierTools. To probe QPTs in SrSi2, we employ the Quantum Lattice environment to simulate a renormalized graphene lattice, mapping analogies between external perturbations and topological responses in both systems. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/42534 |
| institution | University of Cape Town (South Africa) |
| language | English eng |
| last_indexed | 2026-06-10T12:31:35.974Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Department of Physics |
| publisherStr | Department of Physics |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/42534 Modelling of Berry phase and Fermi-level topologies for emergent quantum phenomena prediction in selected solid state systems Tematio, Gaël-Pacôme Nguimeya Salagaram, Trisha Ukpong, Magnus Topological materials Quantum ESPRESSO Topological materials host electronic states that remain robust against perturbations and offer routes to novel quantum functions. This thesis investigates three representative compounds - SrSi2, CoSi, and NbP - to reveal how external stimuli, namely tensile strain and electric fields, tune their electronic bands and topological traits. By combining first-principles calculations with model Hamiltonian experiments, we aim to uncover mechanisms behind quantum phase transitions (QPTs) and to establish design principles for materials with tailored quantum states. We perform density functional theory (DFT) calculations within the plane-wave pseudopotential framework using the Quantum ESPRESSO (QE) suite. Spin-orbit coupling (SOC) is included to capture relativistic effects critical for topological properties. We generate maximally localized Wannier functions (MLWFs) with Wannier90 and construct tight-binding (TB) models to compute Berry curvature, surface state spectra, and Fermi arc patterns via WannierTools. To probe QPTs in SrSi2, we employ the Quantum Lattice environment to simulate a renormalized graphene lattice, mapping analogies between external perturbations and topological responses in both systems. 2026-01-13T06:59:53Z 2026-01-13T06:59:53Z 2025 2026-01-13T06:57:19Z Thesis / Dissertation Doctoral PhD http://hdl.handle.net/11427/42534 en eng application/pdf Department of Physics Faculty of Science University of Cape Town |
| spellingShingle | Topological materials Quantum ESPRESSO Tematio, Gaël-Pacôme Nguimeya Modelling of Berry phase and Fermi-level topologies for emergent quantum phenomena prediction in selected solid state systems |
| thesis_degree_str | Doctoral |
| title | Modelling of Berry phase and Fermi-level topologies for emergent quantum phenomena prediction in selected solid state systems |
| title_full | Modelling of Berry phase and Fermi-level topologies for emergent quantum phenomena prediction in selected solid state systems |
| title_fullStr | Modelling of Berry phase and Fermi-level topologies for emergent quantum phenomena prediction in selected solid state systems |
| title_full_unstemmed | Modelling of Berry phase and Fermi-level topologies for emergent quantum phenomena prediction in selected solid state systems |
| title_short | Modelling of Berry phase and Fermi-level topologies for emergent quantum phenomena prediction in selected solid state systems |
| title_sort | modelling of berry phase and fermi level topologies for emergent quantum phenomena prediction in selected solid state systems |
| topic | Topological materials Quantum ESPRESSO |
| url | http://hdl.handle.net/11427/42534 |
| work_keys_str_mv | AT tematiogaelpacomenguimeya modellingofberryphaseandfermileveltopologiesforemergentquantumphenomenapredictioninselectedsolidstatesystems |