A 'checkerboard' electronic crystal state in lightly hole-doped Ca2-xNaxCuO2Cl2

T Hanaguri, C Lupien, Y Kohsaka, DH Lee, M Azuma, M Takano, H Takagi, James C Davis

Research output: Contribution to journalArticlepeer-review

573 Citations (Scopus)

Abstract

The phase diagram of hole-doped copper oxides shows four different electronic phases existing at zero temperature. Familiar among these are the Mott insulator, high-transition-temperature superconductor and metallic phases. A fourth phase, of unknown identity, occurs at light doping along the zero-temperature bound of the 'pseudogap' regime(1). This regime is rich in peculiar electronic phenomena(1), prompting numerous proposals that it contains some form of hidden electronic order. Here we present low-temperature electronic structure imaging studies of a lightly hole-doped copper oxide: Ca2-xNaxCuO2Cl2. Tunnelling spectroscopy (at energies \E\ > 100 meV) reveals electron extraction probabilities greatly exceeding those for injection, as anticipated for a doped Mott insulator. However, for \E\ < 100 meV, the spectrum exhibits a V-shaped energy gap centred on E = 0. States within this gap undergo intense spatial modulations, with the spatial correlations of a four CuO2-unit-cell square 'checkerboard', independent of energy. Intricate atomic-scale electronic structure variations also exist within the checkerboard. These data are consistent with an unanticipated crystalline electronic state, possibly the hidden electronic order, existing in the zero-temperature pseudogap regime of Ca2-xNaxCuO2Cl2.

Original languageEnglish
Pages (from-to)1001-1005
Number of pages5
JournalNature
Volume430
Issue number7003
DOIs
Publication statusPublished - 26 Aug 2004

Keywords

  • HIGH-TEMPERATURE SUPERCONDUCTORS
  • BI2SR2CACU2O8+DELTA
  • CA2CUO2CL2
  • PSEUDOGAP
  • MAGNETISM
  • PHASES
  • MODEL

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