Transport Properties and Optical Conductivity of the adiabatic Su-Schrieffer-Heeger model: a showcase study for rubrene based field effect transistors

Transport properties, spectral function and optical conductivity of the adiabatic one-dimensional Su-Schrieffer-Heeger (SSH) model are studied with particular emphasis on the model parameters suitable for Rubrene single crystals based field effect transistors. We show that the mobility, calculated by using the Kubo formula for conductivity, vanishes unless we introduce an ad hoc broadening of the system energy levels. Furthermore, the apparent contradiction between angle resolved photoemission data and transport properties is clarified by studying the behavior of the spectral function. Finally, a peak in the optical conductivity at very low energy is obtained and discussed in connection with the available experimental data for Rubrene based devices.

Optical conductivity of doped Mott insulator: the interplay between correlation and electron-phonon interaction

The optical conductivity (OC) of cuprates is studied theoretically in the low density limit of the t-t-J-Holstein model. By developing a limited phonon basis exact diagonalization (LPBED) method capable of treating the lattice of largest size 4x4 ever considered, we are able to discern fine features of the mid-infrared (MIR) part of the OC revealing three-peak structure. The two lowest peaks are observed in experiments and the highest one is tacitly resolved in moderately doped cuprates. Comparison of OC with the results of semianalytic approaches and detailed analysis of the calculated isotope effect indicate that the middle-energy MIR peak is of mostly magnetic origin while the lowest MIR band originates from the scattering of holes by phonons.

Temperature dependence of the angle resolved photoemission spectra in the undoped cuprates: self-consistent approach to the t-J-Holstein model

We develop a novel self-consistent approach for studying the angle resolved photoemission spectra (ARPES) of a hole in the t-J-Holstein model giving perfect agreement with numerically exact Diagrammatic Monte Carlo data at zero temperature for all regimes of electron-phonon coupling. Generalizing the approach to finite temperatures we find that the anomalous temperature dependence of the ARPES in undoped cuprates is explained by cooperative interplay of coupling of the hole to magnetic fluctuations and strong electron-phonon interaction.