Publications in Scientific Journals:

F. Marabelli, M. Galli, M. Moscardini, E. Bauer:
"Evolution of optical response in the series YbCu5-xAux";
Physica B: Condensed Matter, 378-380 (2006), 740 - 741.

English abstract:
Physica B: Condensed Matter
Volumes 378-380 , 1 May 2006, Pages 740-741
Proceedings of the International Conference on Strongly Correlated Electron Systems - SCES 2005

Copyright 2006 Elsevier B.V. All rights reserved.

Evolution of optical response in the series YbCu5-xAux

Franco Marabelli a,Matteo Galli a, Marco Moscardini a and Ernst Bauer b

a Department of Physics "A. Volta", University of Pavia, Pavia, I 27100, Italy
b Institute of Solid State Physics, Vienna University of Technology, Wien A-1040, Austria

Available online 24 February 2006.


Optical measurements from the far infrared to ultraviolet and at low temperature are used to study the evolution of Kondo lattice behaviors within the series YbCu5-xAux. Heavy fermion (Kondo lattice) features have been observed in the low energy part of the spectrum of YbCu5, resembling the data of the isostructural YbCu4Ag, but for a shift towards the lowest frequencies of the free carrier behavior (consistent with a lower TK value). By moving to samples with an increasing amount of Au atoms substituting the Cu atoms, three effects can be observed: the closing of the hybridization gap signed by the red shift of a typical structure in the optical conductivity; the increasing amount of broadening effects, possibly related to stoichiometric disorder; the disappearing of a vibrational structure at about 3.5 meV, which could be due or to disordering effects, or to a change in the Yb-Cu (Yb-Au) bonds.

Keywords: Optical response; Kondo lattice

PACS classification codes: 71.27.+a; 75.30.Mb; 78.20.-e

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