Underscreened Kondo lattice model applied to heavy fermion uranium compounds

• Autor(a) principal: Perkins, Natalia B.
• Data de Publicação: 2007
• Outros Autores: Núñez-Regueiro, M.D., Coqblin, Bernard, Iglesias, Jose Roberto
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/104515
• topic: Fermions; Compostos de urânio; Efeito kondo

We present theoretical results for the underscreened Kondo lattice model with localized S=1 spins coupled to a conduction band through a Kondo coupling, JK, and interacting among them ferromagnetically. We use a fermionic representation for the spin operators and expand the Hamiltonian in terms of bosonic fields. For large values of JK, we obtain a ferromagnetically ordered solution and a Kondo regime with a Kondo temperature, TK, larger than the Curie temperature, TC. This finding suggests a scenario for a coexistence of Kondo effect and ferromagnetic order. In some uranium compounds, such as UTe or UCu0.9Sb2, this kind of coexistence has been experimentally observed: they order ferromagnetically with a Curie temperature of order TC 100 K and exhibit a Kondo behavior for T TC. The proposed underscreened Kondo lattice model accounts well for the coexistence between magnetic order and Kondo behavior and yields to a new “ferromagnetic Doniach diagram.”