Thermopower Evolution in Yb(Rh1-xCox)2Si2 Upon 4f Localization

We present thermopower measurements on Yb( Rh 1 - x Co x ) 2 Si 2 . Upon cobalt substitution, the Kondo temperature is decreasing and the single large thermopower minimum observed for YbRh 2 Si 2 splits into two minima. Simultaneously, the absolute thermopower values are strongly reduced due to a we...

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Bibliographic Details
Published in:Journal of low temperature physics 2019-08, Vol.196 (3-4), p.364-374
Main Authors: Stockert, U., Klingner, C., Krellner, C., Zlatić, V., Geibel, C., Steglich, F.
Format: Article
Language:English
Subjects:
Characterization and Evaluation of Materials
Condensed Matter Physics
Magnetic Materials
Magnetism
Physics
Physics and Astronomy
Online Access:Get full text
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Summary:We present thermopower measurements on Yb( Rh 1 - x Co x ) 2 Si 2 . Upon cobalt substitution, the Kondo temperature is decreasing and the single large thermopower minimum observed for YbRh 2 Si 2 splits into two minima. Simultaneously, the absolute thermopower values are strongly reduced due to a weaker exchange coupling between the 4 f and the conduction electron states with increasing x . Pure YbCo 2 Si 2 is considered a stable trivalent system. Nevertheless, we still observe two minima in the thermopower indicative of weak residual Kondo scattering. This is in line with results from photoemission spectroscopy revealing a tiny contribution from Yb 2 + . The value at the high- T minimum in S ( T ) is found to be proportional to the Sommerfeld coefficient for the whole series. This unexpected finding is discussed in relation to recent measurements of the valence and Fermi surface evolution with temperature.
ISSN:0022-2291
1573-7357
DOI:10.1007/s10909-019-02187-6