Imaging the granular structure of high-T-c superconductivity in underdoped Bi2Sr2CaCu2O8+delta

KM Lang, V Madhavan, JE Hoffman, EW Hudson, H Eisaki, S Uchida, James C Davis

Research output: Contribution to journalArticlepeer-review

682 Citations (Scopus)

Abstract

Granular superconductivity occurs when microscopic superconducting grains are separated by non-superconducting regions; Josephson tunnelling between the grains establishes the macroscopic superconducting state(1). Although crystals of the copper oxide high-transition-temperature (high-T-c) superconductors are not granular in a structural sense, theory suggests that at low levels of hole doping the holes can become concentrated at certain locations resulting in hole-rich superconducting domains(2-5). Granular superconductivity arising from tunnelling between such domains would represent a new view of the under-doped copper oxide superconductors. Here we report scanning tunnelling microscope studies of underdoped Bi2Sr2CaCu2O8+delta that reveal an apparent segregation of the electronic structure into superconducting domains that are similar to3nm in size (and local energy gap <50 meV), located in an electronically distinct background. We used scattering resonances at Ni impurity atoms(6) as 'markers' for local superconductivity(7-9); no Ni resonances were detected in any region where the local energy gap &UDelta;>50+/-2.5 meV. These observations suggest that underdoped Bi2Sr2CaCu2O8+delta is a mixture of two different short-range electronic orders with the long-range characteristics of a granular superconductor.

Original languageEnglish
Pages (from-to)412-416
Number of pages6
JournalNature
Volume415
Issue number6870
DOIs
Publication statusPublished - 24 Jan 2002

Keywords

  • PHASE-SEPARATION
  • STATES
  • EXCITATIONS
  • PSEUDOGAP
  • DENSITY
  • OXIDES
  • MODEL

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