Relevant scale of structural disorder for carrier localization in YBa2Cu3O6.9

Abstract

Resistivity measurements on a large number of YBa2Cu3O6.9 films with reduced long-range order of the crystal show that both normal and superconducting carriers are localized within the coherence lengthrc of the crystal ifrc is reduced below ≈ 10 nm. This result suggests that the localized character of the metallic state observed experimentally in cuprates arises from local structural inhomogeneities and disorder in the nm scale, independent of the nature of the metallic and superconducting states in the CuO2 plane.