Stabilization of Kondo Semiconductor State by Sb Doping of CeNi1-δSn1+δ and the General Criterion of Its Appearance

J. Spałek Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków, Poland and A. Ślebarski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland

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Received: 6 11 2007;

Semimetallic off-stoichiometric CeNi1-δSn1+δ-xSbx system with δ≈0.06 is shown to transform into a Kondo semiconductor upon the substitution of few percent of Sb for Sn. The full-gap formation is associated with f-electron localization induced by the combined effect of the collective Kondo-singlet formation and the atomic disorder. Namely, the extra valence electrons introduced with the Sb doping (one per Sb atom) contribute additionally to the formation of the collective Kondo spin-singlet state at low temperatures, as seen by a substantial reduction of the magnetic susceptibility. The precise general definition of the Kondo semiconductor is provided and the difference with either the simple band or the Mott-Hubbard insulators is stressed.

DOI: 10.12693/APhysPolA.114.7 PACS numbers: 71.27.+a, 72.15.Qm, 71.30.+h