Holger Fehske, Ernst-Moritz-Arndt Universitaet Greifswald, 15h15-16h15 SR 4
Charge transport normally takes place in some background medium. To understand how the environment affects the moving carrier and vice versa is a difficult question and in this generality at present perhaps one of the most heavily debated issues in condensed matter physics. We propose a two-channel transport model which captures this interplay by means of a novel fermion-boson coupling in an effective way. The model is analysed in the one-particle sector by exactly calculating the optical conductivity, Drude weight, quasiparticle dispersion and particle-boson correlation functions for a 1D infinite system. Connections to the transport of lattice and spin polarons were established. For the half-filled band case, we determine numerically the groundstate phase diagram and prove that the model exibits a metal-insulator quantum phase transition. The behaviour of the Luttinger liquid charge exponent, the charge excitation gap, the momentum distribution function and the photoemmission spectra show that the metallic phase typifies a repulsive Luttinger liquid, while the insulating phase constitutes a charge density wave. The results are related to the more standard Mott and Peierls transition scenarios.