Effect of Excitonic Correlations on Magnetic Order in Mixed Valence 4f-Systems

  • G. Gangadhar Reddy
  • A. Ramakanth

Abstract

An attractive interaction between conduction electrons and 4f-holes has been incorporated into the periodic Anderson model (PAM). This model Hamiltonian has been approximated by the full mean-field decoupling of the electron-hole interaction and also the 4f Coulomb repulsion. The approximated Hamiltonian is in fact a renormalized PAM where the coupling constants themselves contain terms like average f−, d−, level occupations n1 and nd respectively and the excitonic correlation <d+ f> = γσ which have to be determined self-consistently. The Curie temperature Tc has been studied as a function of the 4f-level position Ef for a fixed Bloch band width W for different values of the particle-hole attractive strength Ufd. The presence or absence of excitonic correlations does not seem to affect the qualitative behaviour of Tc as a function of Ef. However, the presence of Ufd, and γσ-destabi1ize the long range magnetic order which is reflected as a fall in Tc.

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Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • G. Gangadhar Reddy
    • 1
  • A. Ramakanth
    • 1
  1. 1.Department of PhysicsKakatiya UniversityWarangalIndia

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