[Zurück]

M. Galli, E. Bauer, St Berger, C. Dusek, M. Della Mea, H. Michor, D. Kaczorowski, E. Scheidt, F. Marabelli:
"Evolution of ground state properties of YbCu_5-xAu_x ";
Physica, B 312-313 (2002), S. 489 - 491.

Crystalline electric field and Kondo energy scales in YbCu5-xAgx

H. Michora, K. Kreinera, N. Tsujiib, K. Yoshimurab, K. Kosugeb and G. HilscherCorresponding Author Contact Information, E-mail The Corresponding Author, a

a Institut für Festkörperphysik, Technische Universität Wien, Wiedner Hauptstrasse 8-10, A-1040 Wien, Austria
b Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-01, Japan

Received 1 February 2002. Available online 23 April 2002.

Abstract

The specific heat of LuCu5-xAgx reference samples was measured to reanalyse the heavy-fermion behaviour of the isostructural AuBe5-type cubic system YbCu5-xAgx with x=0¯1 which is a series of dense Kondo compounds whose characteristic temperature T0 decreases as x decreases. For YbCu5-xAgx, the small gamma, Greek-value increases from 210 mJ/molK2 for x=1.0 to 550 mJ/molK2 for x=0.0. The analysis of the magnetic susceptibility and of the magnetic contribution to the specific heat in terms of Coqblin¯Schrieffer (CS) model reveals a significant reduction of the effective ground state degeneracy: While YbCu4Ag is well described by the CS model with View Image and T0=150 K, one has to consider a crystalline electric field splitting of the Yb3+ ground state multiplet with an energy scale of the order of 80 K and a Kondo contribution corresponding to the CS model with View Image and T0~30 K in the case of YbCu5, i.e. there is a cross-over of the characteristic energy scales of the Kondo interaction and of the CEF splitting within the series Yb(Cu,Ag)5.

Author Keywords: Kondo effect; Crystalline electric field; Specific heat

PACS classification codes: 75.20.Hr; 75.10.Dg; 65.40.Ba

http://dx.doi.org/10.1016/S0921-4526(02)01129-8