dc.contributorCalegari, Eleonir João
dc.contributorhttp://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4765559T0
dc.contributorTroper, Amos
dc.contributorhttp://lattes.cnpq.br/9920646475671338
dc.contributorChaves, Carlos Mauricio Giesbrecht Ferreira
dc.contributorhttp://lattes.cnpq.br/5695533520447743
dc.creatorLausmann, Ana Claudia
dc.date.accessioned2017-05-02
dc.date.available2017-05-02
dc.date.created2017-05-02
dc.date.issued2014-08-15
dc.identifierLAUSMANN, Ana Claudia. Pseudogap and the specific heat respulsive hubbard model. 2014. 73 f. Dissertação (Mestrado em Física) - Universidade Federal de Santa Maria, Santa Maria, 2014.
dc.identifierhttp://repositorio.ufsm.br/handle/1/9244
dc.description.abstractThe specific heat and the condensation energy of a two-dimensional Hubbard model, suitable to discuss high Tc superconductors (HTSTC), is studied taking into account hopping to first (t) and second (t2) nearest neighbors. Results for the Hubbard model show that the specific heat as a function of the temperature C(T) presents a two peaks structure (DUFFY; MOREO, 1997). The low temperature peak has been associated with spin fluctuation while the high temperature peak is related to charge fluctuation. Experimental results for the specific heat of HTSC s (LORAM et al., 2001), for instance, the YBCO and LSCO, indicate a close relation between the pseudogap and the specific heat. In the present work, we investigate the specific heat by the Green s function method within the n-pole approximation proposed by L. Roth (ROTH, 1969). The specific heat is calculated on the pseudogap and on the superconducting regions. Superconductivity with dx2−y2- wave pairing is considered following the procedure proposed by Beenen and Edwards (BEENEN; EDWARDS, 1995). The analytical expressions for the specific heat and for the condensation energy have been obtained following the formalism presented in reference (KISHORE; JOSHI, 1971). In the present scenario, the pseudogap emerges when the antiferromagnetic (AF) fluctuations (present in the Roth s band shift) become strongly sufficient to push down the region of the nodal point (π,π) on the renormalized quasi-particle bands. We observed that above a given total occupation nT , the specific heat decreases signaling the pseudogap presence. The effects of the antiferromagnetic fluctuations on the condensation energy and on superconductivity are also investigated.x
dc.publisherUniversidade Federal de Santa Maria
dc.publisherBR
dc.publisherFísica
dc.publisherUFSM
dc.publisherPrograma de Pós-Graduação em Física
dc.rightsAcesso Aberto
dc.subjectModelo de Hubbard
dc.subjectPseudogap
dc.subjectFunções de Green
dc.subjectCalor específico
dc.subjectFlutuações antiferromagnéticas
dc.subjectHubbard model
dc.subjectPseudogap
dc.subjectGreen s functions
dc.subjectSpecific heat
dc.subjectAntiferromagnetic fluctuations
dc.titlePseudogap e calor específico de um modelo de hubbard repulsivo
dc.typeDissertação


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