f-Electron Behavior in Rare Earth Based Systems: Localization or Itinerancy?

M. Biasinia,b, J. Rusza,c, G. Ferroa and A. Czopnikd aENEA, Via Don Fiammelli 2, 40129 Bologna, Italy bDepartment of Physics, University of California Riverside, Riverside CA 92521, USA cDepartment of Electronic Structures, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2, Czech Republic dTrzebiatowski Institute of Low Temperature and Structure Research, P.O. Box 937, Wrocław, Poland

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Received: 20 09 2004;

Measurement of the two-dimensional angular correlation of the electron-positron annihilation radiation complemented with ab initio calculations can provide decisive information about the character of the f-electrons in rare earth compounds. We provide examples of f-electron localized and f-electron itinerant systems, respectively. (i) In the case of the antiferromagnetic heavy fermion and superconductor CeIn3 the multisheet Fermi surface, reconstructed from our measurements in the paramagnetic phase, agrees closely with the predictions of band structure calculations regarding the Ce 4f electrons as fully localized. (ii) On the other hand, our studies of the antiferromagnet actinide based UGa3 in the paramagnetic phase, compared with calculations which include the effects due to the non-uniform positron density and the electron-positron correlations, produce a substantial evidence that an unconstrained 5f-electron itinerant description applies.

DOI: 10.12693/APhysPolA.107.554 PACS numbers:71.18.+y, 71.27.+a, 78.70.Bj