TY - JOUR
T1 - Underscreened Kondo lattice model applied to heavy fermion uranium compounds
AU - Perkins, N. B.
AU - Núñez-Regueiro, M. D.
AU - Coqblin, B.
AU - Iglesias, J. R.
PY - 2007/9/5
Y1 - 2007/9/5
N2 - 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 U Cu0.9 Sb2, 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."
AB - 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 U Cu0.9 Sb2, 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."
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U2 - 10.1103/PhysRevB.76.125101
DO - 10.1103/PhysRevB.76.125101
M3 - Article
AN - SCOPUS:34548751864
SN - 1098-0121
VL - 76
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 12
M1 - 125101
ER -