Thermodynamical properties of the Falicov-Kimbal Model with two spinless impurities

Author(s)

Luís Roberto Ramos

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT)
• Defense date: 2002-11-29

Examining board members

Valter Luiz Libero; Tereza Cristina da Rocha Mendes; Eduardo Miranda; Nelson Studart Filho; Carlos Seihiti Orii Yokoi

• Advisor: Valter Luiz Libero

Abstract

In this work, we study the Falicov-Kimball model with two localized spinless impurities hybridized with conduction electrons of a host metal, therefore, valence fluctuation is intrinsic to the model. The conduction states are also electrostatically scattered whenever a charge is present em the local levels of the impurities. The study was realized computing thermodynamics properties of the model, more specifically, we analyze the temperature dependent specific heat end charge susceptibility for many different parameters of the model. The Numerical Renormalization Group with two discretization parameters is used to obtain the spectrum of the model, from what the thermodynamics is obtained. We discuss the importance of going beyond the usual approximation that projects all moment at the Fermi Level. We begun our study of the thermodynamical properties analyzing values of the parameters space, where the model becomes quadratic (that is, where hybridization or Coulomb scattering are absent), and thus simple interpretations of the data are possible. We verified, for example, that for non-zero hybridization, the system shows Fermi liquid behavior at low temperature. The Wilson ratio, defined here with the charge susceptibility instead of magnetic one, has the universal value R = 1, whenever the hybridization is present. For some choices of the model parameters the model behaviors like heavy fermion. (AU)