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Título: ANTIFERROMAGNETISM AND QUANTUM CRITICAL POINT IN CECOGE(2,1)SI(0,9) COMPOUND UNDER PRESSURE
Autor: MARIELLA ALZAMORA CAMARENA
Colaborador(es): HORTENCIO ALVES BORGES - Orientador
MAGDA BITTENCOURT FONTES - Coorientador
Catalogação: 01/ABR/2008 Língua(s): PORTUGUESE - BRAZIL
Tipo: TEXT Subtipo: THESIS
Notas: [pt] Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio.
[en] All data contained in the documents are the sole responsibility of the authors. The data used in the descriptions of the documents are in conformity with the systems of the administration of PUC-Rio.
Referência(s): [pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=11502&idi=1
[en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=11502&idi=2
DOI: https://doi.org/10.17771/PUCRio.acad.11502
Resumo:
Studies on the pseudo ternary system CeCoGeSix (where 0 = < x = < ) have shown that the system evolves continuously from a Kondo lattice antiferromagnetic state ( CeCoGe(3) with ) towards a mixed valent compound ( CeCoSi(3)with Tw ~230k ). The system displays a non-Fermi-liquid-type behavior (NFL) in the vicinity of the quantum critical point (QCP) at the critical concentration . Isoelectronic substitution of atoms for does not enhance the degree of magnetic disorder, rendering it ideal for the study of the Kondo lattice¡ s interaction constants intrinsic effects. We have studied this system in polycrystalline samples at concentrations close to the critical one through AC electrical resistivity under pressure (x= 0,9) and magnetic field (x=1) measurements. Our results show that the long range magnetic order present in the CeCoGe(2,1)Si(0,9) sample is suppressed as pressure is increased, and that for the critical pressure PC (aprox. 6,2 kbar), TN (aprox. zero) . For temperatures below TN, the resisitivity data are well described considering conduction electron scattering by anisotropic antiferromagnetic magnons. Above PC we observe the Fermi liquid behavior. At the critical region, a NFL state with exponents close to 1 was found. The analysis of the behavior of the critical line in the neighborhood of the QCP indicates that the relevant magnetic fluctuations are typically two-dimensional. On the other hand, the CeCoGe(2)Si compound displays short range order (TN ~ 2k). The ordering temperature is reduced under an increase of an applied magnetic field, and for magnetic fields above 3 T a Fermi liquid behavior arises.
Descrição: Arquivo:   
COVER, ACKNOWLEDGEMENTS, RESUMO, ABSTRACT, SUMMARY AND LISTS PDF    
CHAPTER 1 PDF    
CHAPTER 2 PDF    
CHAPTER 3 PDF    
CHAPTER 4 PDF    
CHAPTER 5 PDF    
CHAPTER 6 PDF    
REFERENCES PDF