Coherence and superconductivity in coupled one-dimensional chains:: A case study of YBa2Cu3Oy -: art. no. 137004

We report the infrared (IR) response of Cu-O chains in the high-T-c superconductor YBa2Cu3Oy over the doping range spanning y=6.28-6.75. We find evidence for a power law scaling at mid-IR frequencies consistent with predictions for Tomonaga-Luttinger liquid, thus supporting the notion of one-dimensional transport in the chains. We analyze the role of coupling to the CuO2 planes in establishing metallicity and superconductivity in disordered chain fragments.