SAIP2016

Ce_1-xLa_xCu₄Al as a case study for the investigation of Ce 4<i>f</i> wave function evolution from a coherent to a local Kondo effect

5 Jul 2016, 16:10

1h 50m

Kramer Law building

Board: A.040

Poster Presentation Track A - Division for Physics of Condensed Matter and Materials Poster Session (1)

Speaker

Dr Emanuela Carleschi (Department of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa)

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Yes

Abstract content <br> &nbsp; (Max 300 words)<br><a href="http://events.saip.org.za/getFile.py/access?resId=0&materialId=0&confId=34" target="_blank">Formatting &<br>Special chars</a>

CeCu₄Al is a heavy fermion system as well as a dense Kondo lattice, where long-range antiferromagnetic correlations emerge as a result of the strong hybridization between the Ce 4f and conduction electrons. The gradual replacement of Ce by La in the diluted series Ce_1-xLa_xCu₄Al leads to an increase of the lattice parameters due to the larger ionic radius of La, which results in the gradual decrease of the Ce 4f hybridization strength. Consequently, the Kondo exchange coupling goes from being fully coherent towards a local/incoherent on-site effect as the La content increases.

We have used Ce_1-xLa_xCu₄Al as a case study for the investigation of the changes in the electronic structure during the coherent-to-incoherent transition of the character of the Ce 4f wave function. We have exploited synchrotron-based x-ray absorption and (resonant) photoemission spectroscopies as ideal probing tools of the dual character of the 4f electrons and the extent of the 4f hybridization.

Among other findings, our results show that, while the incoherent part of the Ce 4f wave function is virtually unmodified throughout the series, the effect of La doping is to suppress the coherent Kondo resonance peak at the Fermi level, as well as to shift both the Kondo resonance peak and its spin-orbit counterpart towards the Fermi level. This is in agreement with the trend found in thermoelectric power measurements, and provides the electronic structure fingerprint of the effects of the fine-tuning of the 4f electron hybridization on the Kondo lattice properties in this series of diluted alloys.

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