Heavy Fermions
Mostrando 1-10 de 10 artigos, teses e dissertações.
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1. Efeito Kondo e magnetismo em uma rede Kagome
Neste trabalho estudamos o modelo da rede de Kondo em uma rede kagome, buscando uma maior compreensão dos efeitos da frustração geométrica em sistemas de férmions pesados. Para tanto, fizemos uma aproximação de campo médio no hamiltoniano do sistema que serve para todas as fases do sistema. Analisamos inicialmente o caso não magnético. Obtemos nest
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 2012
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2. Ressonancia de spin eletronico (ERS) em compostos tipo fermions pesadas a base de Iterbio (Yb) / Electron spin resonance (ERS) in Ytterbium (Yb) based heavy fermion compounds
Nesta Dissertação desenvolvemos estudos de Ressonância de Spin Eletrônico (ESR) em monocristais dos compostos tipo férmions pesados YbR h2Si2 e YbAlB4. No caso do sistem YbRh2Si2, exploraramos os experimentos de ESR para três bandas de frequência existentes em nosso laboratório (n = 4,1 GHz (Banda-S), n = 9,4 GHz (Banda-X) e n = 34,0 GHz (Banda-Q)),
Publicado em: 2009
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3. Doping phase diagrams of the heavy fermions Ce2MIn8 (M = Rh, IR) / Efeitos da substituição quimica nos diagramas de fases dos fermions pesados Ce2MIn8 (M = Rh e Ir)
This thesis describes the investigation of the physical properties of the (Cd, Sn, Ga)-doped Ce2MIn8 (M = Rh, Ir) intermetallic compounds. Temperature dependent magnetic susceptibility, heat capacity and electrical resistivity measurements were performed to characterize the macroscopic properties of the synthesized compounds. X-ray powder diffraction were us
Publicado em: 2009
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4. ANTIFERROMAGNETISM AND QUANTUM CRITICAL POINT IN CECOGE(2,1)SI(0,9) COMPOUND UNDER PRESSURE / ANTIFERROMAGNETISMO E PONTO CRÍTICO QUÂNTICO NO COMPOSTO CECOGE(2,1)SI(0,9) SOB PRESSÃO
Estudos no sistema pseudoternário CeCoGe(3-x)Six (com 0 =
Publicado em: 2007
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5. PRESSURE-TEMPERATURE-COMPOSITION PHASE DIAGRAM OF THE HEAVY FERMION COMPOUND CE2RH(1−X)IR(X)IN8 / DIAGRAMA DE FASES PRESSÃO-COMPOSIÇÃO-TEMPERATURA DO COMPOSTO FÉRMION PESADO CE2RH(1−X)IR(X)IN8
Heavy fermion compounds behave differently from typical metals at low temperatures, where the phenomena that arise due to the correlation between conduction electrons and the f ions of the lattice become evident. An increased effective electronic mass that can reach values as high as hundreds of times the free electron mass and the coexistence of magnetic or
Publicado em: 2006
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6. Quantum critical point in heavy fermions
The concept that heavy fermions are close to a quantum critical point and that this proximity determines their physical behavior has opened new perspectives in the study of these systems. It has provided a new paradigm for understanding and probing the properties of these strongly correlated materials. Scaling ideas were important to establish this approach.
Brazilian Journal of Physics. Publicado em: 2005-03
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7. PHYSICS OF STRONGLY CORRELATED AND DISORDERED SYSTEMS / FÍSICA DE SISTEMAS FORTEMENTE CORRELACIONADOS E DESORDENADOS
In this thesis we study the properties of strongly correlated and disordered materials, using model Hamiltonians to describe them. The thesis is divided in two parts. The first one studies the periodic Anderson model used to describe the properties of a Kondo insulator. In particular we take Ce3Bi4Pt3 as a paradigmatic compound, characterized by a small gap(
Publicado em: 2004
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8. Estudo do efeito kondo na serie de compostos La1-x Ybx Cu3 AL2
The electrical resistivity (r) and the specific heat ( c) were measured for the series of compounds Lal-xYbxCu3Al2 (0x1). The system was characterized using X-ray diffraction and metallography and shows the hexagonal structure for all samples with the CaCu5 type. The unit cell volume Íncreases as the La concentration increases. The resistivity results prese
Publicado em: 1998
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9. Cálculo, via grupo de renormalização, da relaxação nuclear de uma impureza em meio metálico. / Renormalization group calculation of nuclear spin-lattice relaxation for one impurity in a metal.
The nuclear magnetic relaxation rate for an impurity in a metallic environment has been calculated as a function of temperature. Our calculations are based on the spin-degenerate Anderson model originally developed to describe dilute magnetic alloys. The relevance to heavy férmions, Valence fluctuation, and chemisorption on metallic surfaces is discussed. T
Publicado em: 1989
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10. The physics and chemistry of heavy fermions.
The heavy fermions are a subset of the f-electron intermetallic compounds straddling the magnetic/nonmagnetic boundary. Their low-temperature properties are characterized by an electronic energy scale of order 1-10 K. Among the low-temperature ground states observed in heavy fermion compounds are exotic superconductors and magnets, as well as unusual semicon