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TT: Tiefe Temperaturen

TT 14: Postersitzung II: Korrelierte Systeme(1-40), Theorie der Supraleitung(41-50), Metall-Isolator-Übergang, Lokalisierung(51-66), Niederdimensionale Systeme, Quantenhalleffekt(67-80), Pinning, kritische Ströme und Vortexdynamik(81-93), HTSL-Drähte und -Bänder(94-98), Massive HTSL(99-104), supraleitende Borkarbide(105-109)

TT 14.1: Poster

Mittwoch, 19. März 1997, 15:00–18:30, Z1

Charge-spin separation and non-Fermi liquid physics in the normal state of 1D charge density wave systems? — •Johannes Voit — Univ. Bayreuth und Univ. of New South Wales, Sydney

We construct the spectral function of a spin-gapped Luttinger (i.e. Luther-Emery) liquid with dominant CDW correlations and show that the density of states vanishes at frequencies below the gap. The gap-edge singularity is wiped out by the massless charge fluctuations, and beyond the gap, the density of states rises as a power-law with an exponent characterized by the charge stiffness K_ρ. The angle-resolved function has strong shadow bands but surprisingly only a single singularity in the main band. The second singularity of the underlying Luttinger liquid is cut off to a finite maximum by the opening of the spin gap. These features as well as the implied two-step scenario of the CDW transition are compatible with many experimental features of K_0.3 Mo O₃. We discuss a recent suggestion (Q. Si, cond-mat/9507050) that in the presence of charge-spin separation, the charge and spin conductivities of an itinerant electron system would have different temperature dependences. Both conductivities have been measured by others in the quasi-1D CDW system (fluoranthene)₂(PF)₆ and show similar temperature dependence and apparently do not provide evidence for charge-spin separation. It is argued that the blue bronze K_0.3Mo O₃ possesses intermediate-to-weak electron-phonon coupling while most other materials are in the strong-coupling limit. The author is a Heisenberg fellow of DFG.