Regensburg 2004 – wissenschaftliches Programm
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M: Metallphysik
M 18: Postersitzung
M 18.29: Poster
Dienstag, 9. März 2004, 14:30–16:30, Saal C
Electronic density of states in the LaHx-System — •Sandra Heck, Stephan Leyer, Gerda Fischer, and Elmar Dormann — Physikalisches Institut, Universität Karlsruhe, D-76128 Karlsruhe
As has been known for more than fourty years, rare-earth dihydrides like LaH2.0 are metals and the trihydrides (LaH3.0) are semiconductors. The metal-non-metal transition of the LaHx-system was first observed in 1957 [1]. Shinar et al. ([2] 1990) determined the transition concentration to x = 2.86. Whereas it is well known that band filling and atomic order play a significant role in this transition, important aspects are currently not understood. Recent interest in this field dates from the observation that rare-earth hydride mirrors can be switched reversibly from reflectivity to transparency for visible light via the hydrogen content. We carried out measurements of the Pauli-susceptiblility, the 139La Knight-shift and the 139La spin-lattice relaxation rate in order to obtain the concentration dependence of the electronic density of states at the Fermi-level (DOS). These results are compared with earlier NMR [3] and specific-heat [4] data. We thank R. Barnes and G. Majer for disposal of samples.
[1] B. Stalinski, Bull. Acad. Pol. Sci. Cl.III 5, 1001 (1957)
[2] J. Shinar, B. Dehner, R. G. Barnes and B. J. Beaudry, Phys. Rev. Lett. 64, 563 (1990)
[3] R. G. Barnes, C. T. Chang, G. Majer, U. Kaess, J. Alloys Compounds 137, 356-357 (2003)
[4] K. Kai, K. A. Gschneidner, Jr., B. J. Beaudry, D. T. Peterson, Phys. Rev. B 40, 6591 (1989)