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Microscopic electronic inhomogeneity in the high-Tc superconductor Bi2Sr2CaCu2O8+x

Abstract

The parent compounds of the copper oxide high-transition-temperature (high-Tc) superconductors are unusual insulators (so-called Mott insulators). Superconductivity arises when they are ‘doped’ away from stoichiometry1. For the compound Bi2Sr2CaCu2O8+x, doping is achieved by adding extra oxygen atoms, which introduce positive charge carriers (‘holes’) into the CuO2 planes where the superconductivity is believed to originate. Aside from providing the charge carriers, the role of the oxygen dopants is not well understood, nor is it clear how the charge carriers are distributed on the planes. Many models of high-Tc superconductivity accordingly assume that the introduced carriers are distributed uniformly, leading to an electronically homogeneous system as in ordinary metals. Here we report the presence of an electronic inhomogeneity in Bi2Sr2CaCu2O8+x, on the basis of observations using scanning tunnelling microscopy and spectroscopy. The inhomogeneity is manifested as spatial variations in both the local density of states spectrum and the superconducting energy gap. These variations are correlated spatially and vary on the surprisingly short length scale of 14 Å. Our analysis suggests that this inhomogeneity is a consequence of proximity to a Mott insulator resulting in poor screening of the charge potentials associated with the oxygen ions left in the BiO plane after doping, and is indicative of the local nature of the superconducting state.

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Figure 1: Topographic image and associated integrated LDOS map of an optimally oxygen-doped, nominally pure single crystal of Bi2Sr2CaCu2O8+x.
Figure 2: A comparison of an integrated LDOS map and its corresponding superconducting gap map, including their associated statistical results.
Figure 3: Spatial variation of the tunnelling differential conductance spectrum.
Figure 4: A scatter plot of the superconducting gap versus integrated LDOS.

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References

  1. Anderson, P. W. The Theory of Superconductivity in the High-Tc Cuprates (Princeton Univ. Press, Princeton, New Jersey, 1997).

    Google Scholar 

  2. Hudson, E. W., Pan, S. H., Gupta, A. K., Ng, K.-W. & Davis, J. C. Atomic-scale quasiparticle scattering resonances in Bi2Sr2CaCu2O8+δ. Science 285, 88–91 (1999).

    Article  ADS  CAS  Google Scholar 

  3. Pan, S. H. et al. Imaging the effects of individual zinc impurity atoms on superconductivity in Bi2Sr2CaCu2O8+δ. Nature 403, 746–750 (2000).

    Article  ADS  CAS  Google Scholar 

  4. Renner, Ch. et al. Pseudogap precursor of the superconducting gap in under- and overdoped Bi2Sr2CaCu2O8+δ. Phys. Rev. Lett. 80, 149–152 (1998).

    Article  ADS  CAS  Google Scholar 

  5. Miyakawa, N. et al. Predominantly superconducting origin of large energy gaps in underdoped Bi2Sr2CaCu2O8+x from tunneling spectroscopy. Phys. Rev. Lett. 83, 1018–1021 (1999).

    Article  ADS  CAS  Google Scholar 

  6. Hasegawa, H., Ikuta, H. & Kitazawa, K. in Physical Properties of High Temperature Superconductors III (ed. Ginsberg, D. M.) Ch. 7 (World Scientific, Singapore, 1992).

    Google Scholar 

  7. Wolf, E. L., Chang, A., Rong, Z. Y., Ivanchenko, Yu. M. & Lu, F. Direct STM mapping of the superconducting energy gap in single crystal Bi2Sr2CaCu2O8+x. J. Superconductivity 70, 355–360 (1994).

    Article  ADS  Google Scholar 

  8. Ino, A. et al. Doping dependent density of states and pseudogap behavior in La2-xSrxCuO4. Phys. Rev. Lett. 81, 2124–2127 (1998).

    Article  ADS  CAS  Google Scholar 

  9. Fong, H. F. et al. Neutron scattering from magnetic excitations in Bi2Sr2CaCu2O8+δ. Nature 398, 588–591 (1999).

    Article  ADS  CAS  Google Scholar 

  10. Feng, D. L. et al. Signature of superfluid density in the single-particle excitation spectrum of Bi2Sr2CaCu2O8+δ. Science 289, 277–281 (2000).

    Article  ADS  CAS  Google Scholar 

  11. Ding, H. et al. Coherent quasiparticle weight and its connection to high-Tc superconductivity from angle-resolved photoemission. Preprint cond-mat/0006143 at 〈http://xxx.lanl.gov〉 (2000).

  12. Valla, T. et al. Temperature dependent scattering rates at the Fermi surface of optimally doped Bi2Sr2CaCu2O8+δ. Phys. Rev. Lett. 85, 828–831 (2000).

    Article  ADS  CAS  Google Scholar 

  13. Valla, T. et al. Evidence for quantum critical behavior in the optimally doped cuprate Bi2Sr2CaCu2O8+δ. Science 285, 2110–2113 (1999).

    Article  CAS  Google Scholar 

  14. Kaminski, A. et al. Quasiparticles in the superconducting state of Bi2Sr2CaCu2O8+δ. Phys. Rev. Lett. 84, 1788–1791 (2000).

    Article  ADS  CAS  Google Scholar 

  15. Zhang, Y. et al. Giant enhancement of the thermal Hall conductivity κxy in the superconductor YBa2Cu3O7. Preprint cond-mat/0008140 at 〈http://xxx.lanl.gov〉 (2000).

  16. Bogdanov, P. V. et al. Evidence for an energy scale for quasiparticle dispersion in Bi2Sr2CaCu2O8+δ. Phys. Rev. Lett. 85, 2581–2584 (2000).

    Article  ADS  CAS  Google Scholar 

  17. Palstra, T. T. M. et al. Angular dependence of the upper critical field of Bi2Sr2CaCu2O8+δ. Phys. Rev. B 38, 5102–5105 (1988).

    Article  ADS  CAS  Google Scholar 

  18. Renner, Ch., Revaz, B., Kadowaki, K., Maggio-Aprile, I. & Fischer, Ø. Observation of the low temperature pseudogap in the vortex cores of Bi2Sr2CaCu2O8+δ. Phys. Rev. Lett. 80, 3606–3609 (1998).

    Article  ADS  CAS  Google Scholar 

  19. Pan, S. H. et al. STM studies of the electronic structure of vortex cores in Bi2Sr2CaCu2O8+δ. Phys. Rev. Lett. 85, 1536–1539 (2000).

    Article  ADS  CAS  Google Scholar 

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Acknowledgements

We acknowledge P. A. Lee and E. W. Plummer for their comments. We also thank P. W. Anderson, A. Balatsky, D. A. Bonn, A. Castro-Neto, E. Carlson, M. Franz, L. H. Greene, X. Hu, T. Imai, B. Keimer, S. A. Kivelson, K. Kitasawa, R. B. Laughlin, D.-H. Lee, A. H. MacDonald, A. Millis, N. P. Ong, Z.-X. Shen, H.-J. Tao, X.-G. Wen, Z.-Y. Weng, N.-C. Yeh, G.-M. Zhang and Z.-X. Zhong for helpful discussions. This work was supported by the NSF, the DOE, the Sloan Research Fellowship, the Research Corporation, the Miller Institute for Basic Research and a Grant-in-Aid for Scientific Research on Priority Area and a COE Grant from the Ministry of Education, Japan.

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Pan, S., O'Neal, J., Badzey, R. et al. Microscopic electronic inhomogeneity in the high-Tc superconductor Bi2Sr2CaCu2O8+x. Nature 413, 282–285 (2001). https://doi.org/10.1038/35095012

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