4-8 July 2016
Kramer Law building
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Ce1-xLaxCu4Al as a case study for the investigation of Ce 4f wave function evolution from a coherent to a local Kondo effect

Presented by Dr. Emanuela CARLESCHI on 5 Jul 2016 from 16:10 to 18:00
Type: Poster Presentation
Track: Track A - Division for Physics of Condensed Matter and Materials
Board #: A.040

Abstract

CeCu<sub>4</sub>Al 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 4<i>f</i> and conduction electrons. The gradual replacement of Ce by La in the diluted series Ce<sub>1-x</sub>La<sub>x</sub>Cu<sub>4</sub>Al 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 4<i>f</i> 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<sub>1-x</sub>La<sub>x</sub>Cu<sub>4</sub>Al 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 4<i>f</i> wave function. We have exploited synchrotron-based x-ray absorption and (resonant) photoemission spectroscopies as ideal probing tools of the dual character of the 4<i>f</i> electrons and the extent of the 4<i>f</i> hybridization. Among other findings, our results show that, while the incoherent part of the Ce 4<i>f</i> 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 4<i>f</i> electron hybridization on the Kondo lattice properties in this series of diluted alloys.

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Location: Kramer Law building
Address: UCT Middle Campus Cape Town
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Primary authors

  • Dr. Emanuela CARLESCHI Department of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa
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Co-authors

  • Prof. Andrzej KOWALCZYK Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznan, Poland
  • Dr. Bryan DOYLE Department of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa
  • Dr. Michal FALKOWSKI Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznan, Poland
  • Dr. Elena MAGNANO IOM-CNR Laboratorio TASC, S.S. 14 km 163.5, Area Science Park, 34012 Basovizza (TS), Italy; Department of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa
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