Pseudogaps in nearly one-dimensional metals

The linear chain conductors called the Bechgaard salts are materials where the electronic band is half filled, electron-electron interactions are mode rate and the interchain transfer integral is varied from salt to salt. Spec troscopic evidences point to a transition from a (1D) insulating, Mott-Hubb ard (MH) state to a conducting state when the interchain transfer integral exceeds the MH pseudogap. The conducting state is that of a correlation ind uced semimetal with the majority of charge excitations gapped, and with cha rge-spin separation. Spectroscopic evidences also point to a Tomonaga-Lutti nger liquid at energies exceeding the interchain transfer integral. (C) 200 0 Published by Elsevier Science Ltd.