Estudo teórico da estrutura eletrônica do CeCoIn5

• Autor(a) principal: Claudino, Gustavo Medeiros
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/7467
• topic: Supercondutividade; Sistemas férmions; Magnetismo; Física; 53

Heavy fermion are complex systems with unconventional physical properties. Among these physical properties are the unconventional superconductivity, phase transitions at quantum critical points, non-Fermi liquid behavior (NFL), besides many others. In this thesis, it is studied the electronic structure of CeCoIn5 which is the heavy fermion superconductor with the highest critical temperature. As a first step it is explored how the the electronic structure of the CeCoIn5 compound is modified by the electronic correlations at P = 0 GPa. Latter, is simulated the effects of hydrostatic pressure applied onto the system, in particular, is addressed how the pressure modifies the electronic and magnetic properties of the CeCoIn5. It should be point out that the effects of the pressure on the electronic correlations are taken into account during the calculations. This study was conducted by using the (DFT + U) method, which allows to take into account electronic correlations at specific sites inside the compound. The lattice parameters obtained from our calculations matched the experimental ones reported in the literature for this compound. Also the calculated Bulk modulus was in concordance with the experimental value found in some reports. These results were obtained by including on site repulsive Coulomb terms in the Ce-f, Co-d and Ind orbitals. Regarding the pressure effects, it was demonstrated that the magnetic fluctuations decrease as the pressure increases. This last effect was obtained by taking into account a linear increase of the electronic correlations with the pressure. Finally, the band structure showed no significant changes with the pressure, at least in the pressure range studied here. Nevertheless, the hybridization between the Ce-f band and the conduction bands increase with the applied pressure. This result shows that the dimensionality of the system changes as pressure is applied onto the system. The results obtained in this work are compared with the ones observed in experimental T×P phase diagrams measured in CeCoIn5 single crystals.