Estudo teórico de propriedades eletrônicas de nanoestruturas de carbono
Autor(a) principal: | |
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Data de Publicação: | 2010 |
Tipo de documento: | Tese |
Idioma: | por |
Título da fonte: | Repositório Institucional da Universidade Federal Fluminense (RIUFF) |
Texto Completo: | https://app.uff.br/riuff/handle/1/19107 |
Resumo: | In this thesis we develop theoretical studies on the electronic properties of some graphitic carbon based systems: graphene nanoribbons, graphene multi-terminal devices and carbon nanotubes. The adopted model calculation is based on the tight-binding approximation, the Green's functions theory, the decimation and renormalization method and the Landauer-BÄuttiker formalism for electron conduction. We have considered as well the Peierls approximation to describe systems submitted to magnetic fields. The studies presented here are divided in three major focusses. The first one consists of an analysis of the electronic properties of graphene nanoribbons and how these properties respond to applied electric and magnetic fields. In this ¯rst part, we focus mainly in the possibility of generating energy gap modulations and present a self-consistent treatment of the electronic distribution. In the following, we describe the transport properties of multi-terminal systems containing vacancies at the central conductor. We explore the possibility of electronic transport tuning by means of single and multiple vacancies, highlighting the importance of the graphene sublattices, the presence of additional semiconductor terminals and the formation of delocalized defect states. The third main focus of the work is the realization of a theoretical model for a carbon nanotube based molecular nano-sensor. In this case, we represent a molecule bonded to the nanotube's wall by a local normal vibrational mode with phonon and electron-phonon coupling characteristic energies. The basic idea for the device's operation is that the characteristic energies can be measured from the e®ects caused by the mode in the electronic transport. This comes from the fact that conduction electrons from the nanotube may be scattered inelastically by the phonons associated to the molecule. Last, we present some preliminary results of new electronic properties modulations generated in graphene nanoribbons and carbon nanotubes, when these are submitted to gate voltages that create energy barrier type interfaces. The goal of this study is to explore several geometries for these interfaces so that we can manipulate the electronic distribution and concentrate it in small regions as a focusing scheme. This could be envisaged as a mechanism for the generation of localized magnetic moments. |
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Estudo teórico de propriedades eletrônicas de nanoestruturas de carbonoNanotubos de carbonoGrafenoModelo de ligações fortesFunções de GreenCNPQ::CIENCIAS EXATAS E DA TERRA::FISICAIn this thesis we develop theoretical studies on the electronic properties of some graphitic carbon based systems: graphene nanoribbons, graphene multi-terminal devices and carbon nanotubes. The adopted model calculation is based on the tight-binding approximation, the Green's functions theory, the decimation and renormalization method and the Landauer-BÄuttiker formalism for electron conduction. We have considered as well the Peierls approximation to describe systems submitted to magnetic fields. The studies presented here are divided in three major focusses. The first one consists of an analysis of the electronic properties of graphene nanoribbons and how these properties respond to applied electric and magnetic fields. In this ¯rst part, we focus mainly in the possibility of generating energy gap modulations and present a self-consistent treatment of the electronic distribution. In the following, we describe the transport properties of multi-terminal systems containing vacancies at the central conductor. We explore the possibility of electronic transport tuning by means of single and multiple vacancies, highlighting the importance of the graphene sublattices, the presence of additional semiconductor terminals and the formation of delocalized defect states. The third main focus of the work is the realization of a theoretical model for a carbon nanotube based molecular nano-sensor. In this case, we represent a molecule bonded to the nanotube's wall by a local normal vibrational mode with phonon and electron-phonon coupling characteristic energies. The basic idea for the device's operation is that the characteristic energies can be measured from the e®ects caused by the mode in the electronic transport. This comes from the fact that conduction electrons from the nanotube may be scattered inelastically by the phonons associated to the molecule. Last, we present some preliminary results of new electronic properties modulations generated in graphene nanoribbons and carbon nanotubes, when these are submitted to gate voltages that create energy barrier type interfaces. The goal of this study is to explore several geometries for these interfaces so that we can manipulate the electronic distribution and concentrate it in small regions as a focusing scheme. This could be envisaged as a mechanism for the generation of localized magnetic moments.Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorNesta tese, são abordados estudos teóricos sobre as propriedades eletrônicas de alguns sistemas a base do carbono grafítico: nanofitas de grafeno, sistemas de multi-terminais baseados no grafeno e nanotubos de carbono. O formalismo físico-matemático que utilizamos é baseado na aproximação de ligações fortes, na teoria das funções de Green, no método de dizimação e renormalização destas funções e no formalismo de Landauer-Büttiker para a condução eletrônica. Além disto, consideramos a aproximação de Peierls para descrever a aplicação de campos magnéticos nos sistemas tratados. Os estudos, aqui apresentados, estão divididos em três focos principais. O primeiro consiste de uma análise das propriedades eletrônicas das nanofitas de grafeno e de como estas propriedades respondem a campos magnéticos e elétricos aplicados. Nesta primeira parte, nos concentramos principalmente na possibilidade de se gerar modulações dos gaps de energia e num tratamento auto-consistente da distribuição eletrônica. A seguir, descrevemos as propriedades de transporte dos sistemas de multi-terminais contendo vacâncias no condutor central. Exploramos a possibilidade de se ajustar o transporte eletrônico através de vacâncias únicas e múltiplas, ressaltando a importância das sub-redes do grafeno, da presença de terminais semicondutores adicionais e da formação de estados de defeito deslocalizados. O terceiro problema considerado é a realização de um modelo teórico de um nano-sensor molecular baseado em nanotubos de carbono. Neste caso, representamos uma molécula ligada à parede do nanotubo por um modo normal de vibração local com energias de fônon e acoplamento elétron-fônon características. A idéia básica de funcionamento do dispositivo é que estas energias características podem ser medidas a partir dos efeitos que o modo vibracional causa no transporte eletrônico. Isto decorre do fato de os elétrons de condução do nanotubo poderem sofrer espalhamento inelástico pelos fônons associados à molécula. Finalmente, apresentamos alguns resultados preliminares de novas modulações de propriedades eletrônicas geradas em nanofitas de grafeno e nanotubos de carbono, quando estes são submetidos a potenciais de porta que criam interfaces do tipo barreira de energia. O objetivo deste estudo é explorar diversas geometrias para estas interfaces de forma a manipular a distribuição eletrônica e concentrá-la em regiões pequenas se comparadas ao parâmetro de rede do grafeno. Isto pode ser imaginado como um mecanismo para induzir a formação de momentos magnéticos localizados totalmente manipuláveis.Programa de Pós-graduação em FísicaFísicaLatgé, Andréa BritoCPF:63853710778http://genos.cnpq.br:12010/dwlattes/owa/prc_imp_cv_int?f_cod=K4790329H8Makler, Sergio SaulCPF:00000000010http://lattes.cnpq.br/9746253467394955Ritter, Carlos Ferreira2021-03-10T20:46:30Z2011-04-062021-03-10T20:46:30Z2010-01-01info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisapplication/pdfapplication/octet-streamhttps://app.uff.br/riuff/handle/1/19107porCC-BY-SAinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da Universidade Federal Fluminense (RIUFF)instname:Universidade Federal Fluminense (UFF)instacron:UFF2021-03-10T20:46:30Zoai:app.uff.br:1/19107Repositório InstitucionalPUBhttps://app.uff.br/oai/requestriuff@id.uff.bropendoar:21202024-08-19T10:52:20.090955Repositório Institucional da Universidade Federal Fluminense (RIUFF) - Universidade Federal Fluminense (UFF)false |
dc.title.none.fl_str_mv |
Estudo teórico de propriedades eletrônicas de nanoestruturas de carbono |
title |
Estudo teórico de propriedades eletrônicas de nanoestruturas de carbono |
spellingShingle |
Estudo teórico de propriedades eletrônicas de nanoestruturas de carbono Ritter, Carlos Ferreira Nanotubos de carbono Grafeno Modelo de ligações fortes Funções de Green CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
title_short |
Estudo teórico de propriedades eletrônicas de nanoestruturas de carbono |
title_full |
Estudo teórico de propriedades eletrônicas de nanoestruturas de carbono |
title_fullStr |
Estudo teórico de propriedades eletrônicas de nanoestruturas de carbono |
title_full_unstemmed |
Estudo teórico de propriedades eletrônicas de nanoestruturas de carbono |
title_sort |
Estudo teórico de propriedades eletrônicas de nanoestruturas de carbono |
author |
Ritter, Carlos Ferreira |
author_facet |
Ritter, Carlos Ferreira |
author_role |
author |
dc.contributor.none.fl_str_mv |
Latgé, Andréa Brito CPF:63853710778 http://genos.cnpq.br:12010/dwlattes/owa/prc_imp_cv_int?f_cod=K4790329H8 Makler, Sergio Saul CPF:00000000010 http://lattes.cnpq.br/9746253467394955 |
dc.contributor.author.fl_str_mv |
Ritter, Carlos Ferreira |
dc.subject.por.fl_str_mv |
Nanotubos de carbono Grafeno Modelo de ligações fortes Funções de Green CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
topic |
Nanotubos de carbono Grafeno Modelo de ligações fortes Funções de Green CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
description |
In this thesis we develop theoretical studies on the electronic properties of some graphitic carbon based systems: graphene nanoribbons, graphene multi-terminal devices and carbon nanotubes. The adopted model calculation is based on the tight-binding approximation, the Green's functions theory, the decimation and renormalization method and the Landauer-BÄuttiker formalism for electron conduction. We have considered as well the Peierls approximation to describe systems submitted to magnetic fields. The studies presented here are divided in three major focusses. The first one consists of an analysis of the electronic properties of graphene nanoribbons and how these properties respond to applied electric and magnetic fields. In this ¯rst part, we focus mainly in the possibility of generating energy gap modulations and present a self-consistent treatment of the electronic distribution. In the following, we describe the transport properties of multi-terminal systems containing vacancies at the central conductor. We explore the possibility of electronic transport tuning by means of single and multiple vacancies, highlighting the importance of the graphene sublattices, the presence of additional semiconductor terminals and the formation of delocalized defect states. The third main focus of the work is the realization of a theoretical model for a carbon nanotube based molecular nano-sensor. In this case, we represent a molecule bonded to the nanotube's wall by a local normal vibrational mode with phonon and electron-phonon coupling characteristic energies. The basic idea for the device's operation is that the characteristic energies can be measured from the e®ects caused by the mode in the electronic transport. This comes from the fact that conduction electrons from the nanotube may be scattered inelastically by the phonons associated to the molecule. Last, we present some preliminary results of new electronic properties modulations generated in graphene nanoribbons and carbon nanotubes, when these are submitted to gate voltages that create energy barrier type interfaces. The goal of this study is to explore several geometries for these interfaces so that we can manipulate the electronic distribution and concentrate it in small regions as a focusing scheme. This could be envisaged as a mechanism for the generation of localized magnetic moments. |
publishDate |
2010 |
dc.date.none.fl_str_mv |
2010-01-01 2011-04-06 2021-03-10T20:46:30Z 2021-03-10T20:46:30Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/doctoralThesis |
format |
doctoralThesis |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
https://app.uff.br/riuff/handle/1/19107 |
url |
https://app.uff.br/riuff/handle/1/19107 |
dc.language.iso.fl_str_mv |
por |
language |
por |
dc.rights.driver.fl_str_mv |
CC-BY-SA info:eu-repo/semantics/openAccess |
rights_invalid_str_mv |
CC-BY-SA |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf application/octet-stream |
dc.publisher.none.fl_str_mv |
Programa de Pós-graduação em Física Física |
publisher.none.fl_str_mv |
Programa de Pós-graduação em Física Física |
dc.source.none.fl_str_mv |
reponame:Repositório Institucional da Universidade Federal Fluminense (RIUFF) instname:Universidade Federal Fluminense (UFF) instacron:UFF |
instname_str |
Universidade Federal Fluminense (UFF) |
instacron_str |
UFF |
institution |
UFF |
reponame_str |
Repositório Institucional da Universidade Federal Fluminense (RIUFF) |
collection |
Repositório Institucional da Universidade Federal Fluminense (RIUFF) |
repository.name.fl_str_mv |
Repositório Institucional da Universidade Federal Fluminense (RIUFF) - Universidade Federal Fluminense (UFF) |
repository.mail.fl_str_mv |
riuff@id.uff.br |
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1811823593920659456 |