Issue J. Phys. IV France Volume 114, April 2004 Page(s) 51 - 55 DOI 10.1051/jp4:2004114009

J. Phys. IV France 114 (2004) 51
DOI: 10.1051/jp4:2004114009

Signatures of spin-charge separation in the 1D organic conductor TTF-TCNQ from photoelectron spectroscopy

R. Claessen¹, M. Sing¹, U. Schwingenschlögl¹ and J.M.P. Carmelo<sup>2

1</sup>  Experimentalphysik II, Universität Augsburg, 86135 Augsburg, Germany
    e-mail: claessen@physik.uni-augsburg.de
²  GCEP-Center of Physics, Universidade do Minho, 4710-057 Braga, Portugal

Abstract
We have studied the electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ by angle-resolved photoelectron spectroscopy (ARPES). The data reveal significant discrepancies to conventional band theory. Instead the experimental dispersions can be quantitatively reproduced by the one-dimensional (1D) Hubbard model, if one allows for a surface-enhancement of the hopping integral induced by a relaxation of the tomost molecular layer. The TCNQ-related conduction band is thus found to display spectroscopic signatures of spin-charge separation on the energy scale of the band width. In contrast, the TTF-derived band seems to be only weakly correlated, at variance with other findings. The important role of electronic correlations in this material is further corrborated by a peculiar temperature dependence of the spectra. While the 1D Hubbard model thus yields a good description at finite excitation energies, it fails concerning the low-energy spectral behavior, most likely due to the additional importance of strong electron-phonon interaction and interchain electronic hopping on small energy scales. Key words. One-dimensional metals - Spin-charge separation - Photoemission

© EDP Sciences 2004

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