Conductivity and phase coherence length of single electrons in layered cuprates

Abstract

We present a novel approach to the analysis of the normal-state in-planeσab and out-of-planeσc conductivities of anisotropic layered cuprates with incoherent out-of-plane transport such asYBa2Cu3Ox (6.35 ⩽ x ⩽ 6.93) and Y1 − yPryBa2Cu3O7 − δ (0.08 ⩽ y ⩽ 0.53).We show that the resistive anisotropy σab/σc of these crystals is a measure of the in-plane phasecoherence lengthℓφ,ab. This result has two important implications: i) One can obtain experimentallythe dependence of conductivity on phase coherence length σab,c(ℓφ,ab).This σab,c(ℓφ,ab)-dependence for different doping follows a universal scaling relationship. Thisuniversality ofσab,c(ℓφ,ab) for different doping is a directexperimental confirmation of the scalinghypothesis. ii) σab/σc at a giventemperature changes nonmonotonically with doping, reaching a maximum in the sample closest to the metal-insulatortransition. We show that this result is a consequence of incoherent c-axis conduction.