Yoshio Kuramoto

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