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In certain Sm systems with mixed valence such as SmOs4Sb12 and SmT2Al20 with T=Ti, V, Cr, Ta, etc, the resistivity and specific heat show behaviors reminiscent of the Kondo effect. However, the behaviors are almost independent of applied magnetic field. We ascribe the Kondo-like behavior to charge correlations. Acccoding to our model, the effective hybridization of Sm 4f-electrons is reduced by the orthogonality effect with the Coulomb interaction U between 4f and conduction electrons. The Coulomb interaction also acts to enhance the hybridization via the exciton-like correlation. The orthogonality effect becomes dominant as U and/or the number of conduction channels increases, and eventually makes the effective hybridization vanish. We combine the continuous-time Monte Carlo calculation and the analytic theory to derive the dynamics in the wide temperature range.

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Yoshio Kuramoto, Institute of Materials Structure Science KEK, Tsukuba, Japan
Seminar room 0.03, ETP
Contact: Achim Rosch