For a quantum spin chain or 1D fermionic system, we prove that the Drude weight D verifies the universal Luttinger liquid relation v s = D/κ, where κ is the susceptibility and vs is the Fermi velocity. This result is proved by rigorous Renormalization Group methods and is true for any weakly interacting system, regardless its integrablity. This paper, combined with [1], completes the proof of t...

La8−xSrxCu8O20 is a non-superconducting cuprate, which exhibits a doubling of the elementary cell along the c axis. Its optical conductivity σ(ω) has been first measured here, down to 20 K, in two single crystals with x = 1.56 and x = 2.24. Along c σ(ω) shows, in both samples, bands due to strongly bound charges, thus confirming that the cell doubling is due to charge ordering. In the ab plane,...

Using the Kubo linear response formalism, we study the effects of intrinsic graphene optical and surface polar phonons (SPPs) on the optical conductivity of doped graphene. We find that inelastic electron-phonon scattering contributes significantly to the phonon-assisted absorption in the optical gap. At room temperature, this midgap absorption can be as large as 20–25% of the universal ac cond...

We report on infrared spectroscopic studies of the electronic response of the (Sr1-xLax)3Ir2O7 system. Our experiments revealed hallmarks of strong electronic correlations in the evolution of the electronic response across the filling-controlled insulator-metal transition. We observed a collapse of the Jeff = 1/2 Mott gap accompanying the transfer of the spectral weight from the high-energy reg...

We derive a theoretical expression to calculate the Drude plasma frequency $\omega_p$ based on quantum mechanical time dependent perturbation theory. show that in general $\omega_p^2$ should be replaced by second rank tensor, tensor $\mathcal{D}$, which we express terms of products velocity expectation values integrated over Fermi surface, and is amiable analytical numerical evaluation. For Som...

Reflection electron energy loss spectroscopy (REELS) spectra were measured for seven insulating organic compounds (DNA, Irganox 1010, Kapton, polyethylene [PE], poly(methyl methacrylate) [PMMA], polystyrene [PS] and polytetrafluoroethylene [PTFE]). Optical constants band gaps extracted from the REELS after elimination of multiple scattering via a deconvolution fitting normalised single to Drude...