un 1 99 7 The underscreened Kondo effect : a two S = 1 impurity model
نویسنده
چکیده
The underscreened Kondo effect is studied within a model of two impurities S=1 interacting with the conduction band and via an interimpurity coupling K ~ S1. ~ S2. Using a mean-field treatment of the bosonized Hamiltonian, we show that there is no phase transition, but a continuous cross-over versus K from a non Kondo behaviour to an underscreened Kondo one. For a small antiferromagnetic coupling (K¿0), a completely asymmetric situation is obtained with one s=12 component strongly screened by the Kondo effect and the other one almost free to yield indirect magnetism, which shows finally a possible coexistence between a RKKY interaction and a local Kondo effect, as observed in Uranium compounds such as UPt3. PACS. numbers: 75.20.Hr, 75.30. Mb, 71.27. +a
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