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Cox, S. F. J., Lord, J. S., Hillier, A. D., Cottrell, S. P., Wagner, P. & Ewels, C. P. (2009) Muonium in boron. Physica B, 404 841–844.
Added by: Laurent Cournède (2016-03-10 21:41:24) |
| Type de référence: Article DOI: 10.1016/j.physb.2008.11.156 Numéro d'identification (ISBN etc.): 0921-4526 Clé BibTeX: Cox2009 Voir tous les détails bibliographiques  |
Catégories: PMN Mots-clés: boron, hydrogen, Hydrogen defect centres, Muonium Créateurs: Cottrell, Cox, Ewels, Hillier, Lord, Wagner Collection: Physica B |
Consultations : 1/477
Indice de consultation : 3% Indice de popularité : 0.75% |
| Résumé |
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A paramagnetic muonium centre is detected in elemental boron at cryogenic temperatures and characterized by hyperfine decoupling in longitudinal magnetic fields. The contact term is only 0.52 GHz or 12\% of the free muonium value. An effective ionization energy of 0.1 eV is estimated from polarization transfer to the muon Larmor precession signal in transverse field, beginning around 100 K and complete by room temperature. AIMPRO density functional calculations identify candidate sites for monatomic hydrogen defect centres in the rather complex boron lattice and predict the local distribution of unpaired electron spin density. One of these, bridging between two boron atoms in the inter-icosahedral space, provides an adequate match to the muonium hyperfine parameters, as well as its relatively weak binding energy. Negative-U behaviour is predicted, implying that Ho centres are not thermodynamically stable. Identification of the high diamagnetic muon fraction found at all temperatures is also discussed. (c) 2008 Elsevier B.V. All rights reserved.
Added by: Laurent Cournède |