Berlin 2005 – scientific programme
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TT: Tiefe Temperaturen
TT 31: Correlated Electrons - Low-dimensional Materials I
TT 31.7: Talk
Tuesday, March 8, 2005, 15:30–15:45, TU H2053
Infrared properties of the quasi-one-dimensional superconductor β-Na0.33V2O5 under pressure — •C. A. Kuntscher1, S. Frank1, I. Loa2, K. Syassen2, T. Yamauchi3, and Y. Ueda3 — 11. Physikalisches Institut, Universität Stuttgart, 70550 Stuttgart, Germany — 2Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany — 3Institute for Solid State Physics, University of Tokyo, Tokyo, Japan
At ambient pressure β-Na0.33V2O5 shows a quasi-one-dimensional metallic character at room temperature, which can be explained by its highly anisotropic crystal structure consisting of chains and ladders of VO6 octahedra and chains of VO5 square pyramids. Upon cooling it undergoes a metal-insulator transition at 135 K due to charge ordering on the V sites. The pressure-temperature phase diagram of β-Na0.33V2O5 is remarkable, since it shows a superconducting phase for pressures higher than 7 GPa in direct vicinity to the charge-ordered phase [1]. The mechanism of the observed superconductivity and its relation to the charge ordering is not clear. Besides, electron-phonon interaction seems to play a role as well, influencing the conduction mechanism.
We carried out polarization-dependent reflectivity measurements on β-Na0.33V2O5 at room temperature as a function of pressure (<20 GPa). The results are discussed in terms of the conduction mechanism, pressure-induced structural changes, and charge ordering/redistribution. Supported by the DFG, Emmy Noether-program.
[1] T. Yamauchi, Y. Ueda, and N. Mori, Phys. Rev. Lett. 89, 057002 (2002).