We study the electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ by means of density-functional band theory, Hubbard model calculations, and angle-resolved photoelectron spectroscopy (ARPES). The experimental spectra reveal significant quantitative and qualitative discrepancies to band theory. We demonstrate that the dispersive behavior as well as the temperature dependence of the spectra can be consistently explained by the finite-energy physics of the one-dimensional Hubbard model at metallic doping. The model description can even be made quantitative, if one accounts for an enhanced hopping integral at the surface, most likely caused by a relaxation of the topmost molecular layer. Within this interpretation the ARPES data provide spectroscopic evidence for the existence of spin-charge separation on an energy scale of the conduction bandwidth. The failure of the one-dimensional Hubbard model for the low-energy spectral behavior is attributed to interchain coupling and the additional effect of electron-phonon interaction.
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2003
Bibliographical noteFunding Information:
We are grateful to M. Dressel and C.S. Jacobsen for providing us with single crystals, and thank K. Penc and J. Voit for fruitful discussions. We acknowledge financial support by the Deutsche Forschungsgemeinschaft under grant CL 124/3-1 and the Sonderforschungsbereich 484 at the Universität Augsburg.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics