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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Fases geométricas para quasipartículas em grafeno na presença de deslocações

Garcia, Gabriel Queiroz 15 March 2013 (has links)
Submitted by Vasti Diniz (vastijpa@hotmail.com) on 2017-09-18T14:16:14Z No. of bitstreams: 1 arquivototal.pdf: 2655836 bytes, checksum: 6306e048c6d679513585a208ceaa9e95 (MD5) / Made available in DSpace on 2017-09-18T14:16:14Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2655836 bytes, checksum: 6306e048c6d679513585a208ceaa9e95 (MD5) Previous issue date: 2013-03-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Recently, Mesaros, Sadri and Zaanen investigated the rise of Berry phases in the dynamics of quasiparticle in graphene with edge dislocation. In opposition with disclina­tions, dislocations require only finites energies to be created so that is virtually impossible to prepare one crystal, which doesn't have dislocations. Mesaros, Sadri e Zaanen used the theory of classic elasticity, to introduce informations due deslocations, in the Hamiltonian of particle and also used tigth-binding method to describe the system. They obtained that dynamics particle acquires one Berry phase and which this phase can be used at applications in quantic computation. In this work, we use the Katanev and Volovich geometric theory of defects to introduce dislocations in the graphene's sheet. We obtain the metric which descibe edge dislocations. We obtain the Hamiltonian which descibe the dynamic of quasiparticle in the graphene at curved space-time with torsion. Write the Dirac equation to this system and investigate the rise of Berry phase in this system. We show that Berry phase obtained to our system depends of intensity of Burgers vector. / Recentemente, Mesaros, Sadri e Zaanen investigaram o aparecimento de fases de Berry na dinamica de quasiparticulas em grafeno com deslocagoes tipo edge. Em contraste com desclinagoes, as deslocagoes requerem apenas energias finitas para serem criadas, de modo que é virtualmente impossivel preparar um cristal que nao contem deslocagoes. Mesaros, Sadri e Zaanen usaram a teoria da elasticidade classica, para introduzir as infor­magoes devido a deslocacao, no hamiltoniano da particula e usaram metodo tight-binding numa aproximagao de continuo para descrever o sistema. Eles obtiveram que a dinamica da particula adquire uma fase de Berry e que esta fase pode ser usadas para aplicagoes em computagao quantica. Neste trabalho, usamos a teoria geometrica de defeitos de Katanaev e Volovich para introduzir deslocagoes em uma folha de grafeno em uma aproximagao de continuo. Obtemos a metrica que descreve uma deslocagao tipo edge. Obtemos o hamil­toniano que descreve a dinamica das quasiparticulas no grafeno neste espago curvo com torgao. Escrevemos a equagao de Dirac para esse sistemas e investigamos o aparecimento de fases de Berry neste sistema. Mostramos que a fase geometrica obtida para o nosso sistema depende da intensidade do vetor de Burgers.

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