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Claessen, R.; Sing, M.; Schwingenschlogl, U.; Blaha, P.; Dressel, M.; Jacobsen, Claus Schelde Published in: Physical Review LettersLink to article, DOI: 10.1103/PhysRevLett.88.096402 Publication date: 2002 Document VersionPublisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Claessen, R., Sing, M., Schwingenschlogl, U., Blaha, P., Dressel, M., & Jacobsen, C. S. (2002). Spectroscopic signatures of spin-charge separation in the quasi-one-dimensional organic conductor TTF-TCNQ. Physical Review Letters, 88(9), 096402. DOI: 10.1103/PhysRevLett.88.096402 VOLUME 88, NUMBER 9 The electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ is studied by angle-resolved photoelectron spectroscopy (ARPES). The experimental spectra reveal significant discrepancies to band theory. We demonstrate that the measured dispersions can be consistently mapped onto the one-dimensional Hubbard model at finite doping. This interpretation is further supported by a remarkable transfer of spectral weight as a function of temperature. The ARPES data thus show spectroscopic signatures of spin-charge separation on an energy scale of the conduction bandwidth.

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 ͑ARPES͒. 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.

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