Suppression of gapless edge states in interaction driven topological insulators

A topological insulator is a special class of material where the bulk of the material is gaped, exhibiting insulating properties, and the edges are gapless, exhibiting behaviours of a conductor due to one unpaired electron. This report seeks to investigate if there is any suppression of gapless edge...

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Main Author: Thayalan Raman
Other Authors: Pinaki Sengupta
Format: Final Year Project
Language:English
Published: Nanyang Technological University 2022
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Online Access:https://hdl.handle.net/10356/157023
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1570232023-02-28T23:15:18Z Suppression of gapless edge states in interaction driven topological insulators Thayalan Raman Pinaki Sengupta School of Physical and Mathematical Sciences PSENGUPTA@ntu.edu.sg Science::Physics::Atomic physics::Solid state physics A topological insulator is a special class of material where the bulk of the material is gaped, exhibiting insulating properties, and the edges are gapless, exhibiting behaviours of a conductor due to one unpaired electron. This report seeks to investigate if there is any suppression of gapless edge states when lattice interactions are considered. These conditions were then simulated at ground state in an open-boundary, one-dimensional extended Peierls-Hubbard model at half-filling. A numerical method by the name of stochastic series expansion, a branch of Quantum Monte Carlo methods, is used to run the simulations for finite length models. The model considers electron-electron interactions and a finite range of electron-phonon coupling parameters. Firstly, spin stiffness is used as an indicator to observe the transition to Peierls state at ground temperature for closed boundary conditions at a critical phonon coupling value. This provides details about the critical phonon coupling values. Choosing an appropriate phonon coupling value based on the previous details, a comparison between odd length and even length chains were done at open boundary conditions. It was found that there is always suppression of gapless edge states for both even and odd length chain of sites. Bachelor of Science in Applied Physics 2022-05-06T06:10:53Z 2022-05-06T06:10:53Z 2022 Final Year Project (FYP) Thayalan Raman (2022). Suppression of gapless edge states in interaction driven topological insulators. Final Year Project (FYP), Nanyang Technological University, Singapore. https://hdl.handle.net/10356/157023 https://hdl.handle.net/10356/157023 en application/pdf Nanyang Technological University
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Science::Physics::Atomic physics::Solid state physics
spellingShingle Science::Physics::Atomic physics::Solid state physics
Thayalan Raman
Suppression of gapless edge states in interaction driven topological insulators
description A topological insulator is a special class of material where the bulk of the material is gaped, exhibiting insulating properties, and the edges are gapless, exhibiting behaviours of a conductor due to one unpaired electron. This report seeks to investigate if there is any suppression of gapless edge states when lattice interactions are considered. These conditions were then simulated at ground state in an open-boundary, one-dimensional extended Peierls-Hubbard model at half-filling. A numerical method by the name of stochastic series expansion, a branch of Quantum Monte Carlo methods, is used to run the simulations for finite length models. The model considers electron-electron interactions and a finite range of electron-phonon coupling parameters. Firstly, spin stiffness is used as an indicator to observe the transition to Peierls state at ground temperature for closed boundary conditions at a critical phonon coupling value. This provides details about the critical phonon coupling values. Choosing an appropriate phonon coupling value based on the previous details, a comparison between odd length and even length chains were done at open boundary conditions. It was found that there is always suppression of gapless edge states for both even and odd length chain of sites.
author2 Pinaki Sengupta
author_facet Pinaki Sengupta
Thayalan Raman
format Final Year Project
author Thayalan Raman
author_sort Thayalan Raman
title Suppression of gapless edge states in interaction driven topological insulators
title_short Suppression of gapless edge states in interaction driven topological insulators
title_full Suppression of gapless edge states in interaction driven topological insulators
title_fullStr Suppression of gapless edge states in interaction driven topological insulators
title_full_unstemmed Suppression of gapless edge states in interaction driven topological insulators
title_sort suppression of gapless edge states in interaction driven topological insulators
publisher Nanyang Technological University
publishDate 2022
url https://hdl.handle.net/10356/157023
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