Dresden 2006 – wissenschaftliches Programm
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MM: Metall- und Materialphysik
MM 15: Hydrogen in Metals II
MM 15.4: Vortrag
Dienstag, 28. März 2006, 12:30–12:45, IFW D
Raman spectroscopy study of strong correlation effects in YH3−δ — •A.-M Racu and J. Schoenes — Institut für Physik der Kondensierten Materie - TU Braunschweig Mendelssohnstrasse 3, 38106 Braunschweig
Temperature dependent Raman measurements on insulating YH3−δ thin films have been performed from 4 K to 450 K. The most striking effect is the broadening by a factor of almost 6 between 4 and 300 K of a particular mode, which is assigned to a breathing vibration of the yttrium atoms. For higher temperatures, the line-width of this mode saturates, which is rather unusual for a phonon.
We developed a model which discusses the line broadening in terms of a coupling between this breathing mode and the electron excited from an octahedral H-vacancy into the 4d conduction band of Y. The data strongly support the correlated electron theory proposed by Ng et al. [1] for the metal-insulator transition in YHx.
[1] K. K. Ng, F. C. Zhang, V. I. Anisimov, T. M. Rice, Phys. Rev. B 59, 5398 (1999).