The ab-plane optical conductivity of overdoped La2−xSrxCuO4 for x=0.184 and 0.22: evidence of a pseudogap

Phase Diagram ofLa2−xSrxC

“…Either the maximum width related to increasing fluctuations around the insulatorto-metal transition and the minimum around the commensurate value x = 0.125 are observed by both techniques. Figure 2 can hardly be explained in terms of alternative models 16,17 for the far-infrared peaks of LSCO, and provides strong support to the interpretation of the present data in terms of charge stripe excitations.…”

“…Far-infrared peaks similar to those reported here were observed previously in a few superconducting samples of La 2-x Sr x CuO 4+y, either oxygen-doped 16 or Sr-doped. 17 In the former case those peaks were tentatively assigned to polarons, in the latter case to disorder effects related to the Sr impurities. However, either for isolated 18 or for interacting polarons 19,20 the main absorption is predicted at frequencies higher than ω LO , where LO is a longitudinal optical mode of the polar lattice.…”

Raman scattering versus infrared conductivity: Evidence for one-dimensional conduction inLa2−xSrxVenturini1, Zhang2, Hackl3 et al. 2002Phys. Rev. B449310View full textAdd to dashboardCite

“…They were attributed to disorder and analyzed in terms of an "anomalous Drude" model. 14 In the present work, the comparison of IR and Raman data allows us to get deeper insight into the origin of the strong absorption peaks of LSCO shown in Fig. 2.…”

Anomalous Optical Absorption in the Normal State of Overdoped Cuprates Near the Charge-Ordering Instability

“…The extrapolation to zero frequency of this latter spectral contribution matches well with the d.c. value σ(ω = 0, T ) as obtained from transport data. Althought this is the only case where a separate narrow Drude term is directly observed, there are other cases both in hole-and electron-doped cuprates, like La 2−x Sr x CuO 4 (LSCO, x = 0.184, 0.22) [2] and Nd 2−x Ce x CuO 4−y at x > ∼ 0.15 (NCCO) [3,4], where a strongly temperature dependent peak at a finite frequency Ω Max is observed. Moreover, in LSCO, for ω < Ω Max , σ(ω) decreases and moves away from the substantially higher d.c. value.…”