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SYNF: Non-Fermi Liquids in Quantum Structures

SYNF 1: Non-Fermi Liquids in Quantum Structures

SYNF 1.6: Hauptvortrag

Donnerstag, 11. März 2004, 17:55–18:30, H 1

Spectroscopic signatures of spin-charge separation in a quasi-one-dimensional organic conductor — •Ralph Claessen — Experimentalphysik II, Universität Augsburg, D-86135 Augsburg

In interacting one-dimensional (1D) metals conventional Fermi liquid behavior is expected to break down due to a dynamical decoupling of charge and spin degrees of freedom. Angle-resolved photoelectron spectroscopy (ARPES) on the electronic structure of the quasi-1D organic conductor TTF-TCNQ [1] indeed reveals significant discrepancies to band theory. Instead, the experimental spectra can be well explained by the 1D Hubbard model [2], which accounts for the intramolecular Coulomb interaction and predicts signatures of spin-charge separation over the entire conduction band width. The model description can even be made quantitative, if one accounts for an enhanced hopping integral at the surface related to a relaxation of the topmost molecular layer. The importance of strong 1D correlation effects is further supported by a remarkable temperature dependence of the ARPES data. These results provide strong spectroscopic evidence for the occurence of spin-charge separation in the finite energy physics of TTF-TCNQ. Deviations of the Hubbard model description for the low-energy spectral behavior is attributed to the neglect of interchain coupling, long-range Coulomb interaction and/or electron-phonon coupling.

[1] R. Claessen et al., Phys. Rev. Lett. 88, 096402 (2002).

[2] M. Sing et al., Phys. Rev. B 68, 125111 (2003).