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Phys. Rev. B 75, 235109 (2007) [8 pages]

Temperature-independent ytterbium valence in YbGaGe

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B. P. Doyle1,*, E. Carleschi2,1, E. Magnano1, M. Malvestuto3, A. A. Dee4,5,6, A. S. Wills4,5, Y. Janssen7, and P. C. Canfield7,8
1Laboratorio Nazionale TASC, INFM-CNR, S.S. 14, km 163.5, Area Science Park, 34012 Basovizza (TS), Italy
2Dipartimento di Fisica, Università degli Studi di Trieste, via A. Valerio 2, 34127 Trieste, Italy
3Sincrotrone Trieste S.C.p.A, S.S. 14 km 163.5, Area Science Park, 34012 Basovizza (TS), Italy
4Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, United Kingdom
5Davy Faraday Research Laboratory, The Royal Institution of Great Britain, 21 Albemarle Street, London W1S 4BS, United Kingdom
6Institute Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
7Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA
8Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA

Received 4 November 2006; published 12 June 2007

We have determined the ytterbium valence as a function of temperature in the reported near-zero thermal expansion material YbGaGe using x-ray photoemission at various incident photon energies. The Yb 3d, 4d, and 4f levels, which directly yield the Yb valence, have been measured. Careful analysis enabled the clear separation of surface and bulk contributions. Resonant photoemission at the 4d-4f absorption edge was used to enhance the low contribution of the Yb3+ component. Contrary to the initially proposed Yb valence transition, we find no change in the valence from room temperature down to 115 K.

© 2007 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.75.235109
DOI:
10.1103/PhysRevB.75.235109
PACS:
65.40.De, 75.30.Mb, 71.20.Eh, 79.60.−i

*Electronic address: doyle@tasc.infm.it