Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Emergence of preformed Cooper pairs from the doped Mott insulating state in Bi2Sr2CaCu2O8+δ

Abstract

Superconductors are characterized by an energy gap that represents the energy needed to break the pairs of electrons (Cooper pairs) apart. At temperatures considerably above those associated with superconductivity, the high-transition-temperature copper oxides have an additional ‘pseudogap’. It has been unclear whether this represents preformed pairs of electrons that have not achieved the coherence necessary for superconductivity, or whether it reflects some alternative ground state that competes with superconductivity1. Paired electrons should display particle–hole symmetry with respect to the Fermi level (the energy of the highest occupied level in the electronic system), but competing states2,3,4 need not show such symmetry. Here we report a photoemission study of the underdoped copper oxide Bi2Sr2CaCu2O8+δ that shows the opening of a symmetric gap only in the anti-nodal region, contrary to the expectation that pairing would take place in the nodal region. It is therefore evident that the pseudogap does reflect the formation of preformed pairs of electrons and that the pairing occurs only in well-defined directions of the underlying lattice.

Your institute does not have access to this article

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Analysis of spectra from the optimally doped material.
Figure 2: Spectra from the optimally doped and underdoped material in the superconducting state.
Figure 3: Spectra from the optimally doped and underdoped material in the normal state.
Figure 4: Analysis of spectra recorded along the anti-nodal direction.

References

  1. Timusk, T. & Statt, B. The pseudogap in high-temperature superconductors: an experimental survey. Rep. Prog. Phys. 62, 61–122 (1999)

    ADS  CAS  Article  Google Scholar 

  2. Valla, T. et al. Quasiparticle spectra, charge-density waves, superconductivity, and electron-phonon coupling in 2H-NbSe2 . Phys. Rev. Lett. 92, 086401 (2004)

    ADS  CAS  Article  Google Scholar 

  3. Schäfer, J. et al. Direct spectroscopic observation of the energy gap formation in the spin density wave phase transition at the Cr(110) surface. Phys. Rev. Lett. 83, 2069–2072 (1999)

    ADS  Article  Google Scholar 

  4. Chakravarty, S., Laughlin, R. B., Morr, D. K. & Nayak, C. Hidden order in the cuprates. Phys. Rev. B 63, 094503 (2001)

    ADS  Article  Google Scholar 

  5. Damascelli, A., Hussain, Z. & Shen, Z.-X. Angle-resolved photoemission studies of the cuprate superconductors. Rev. Mod. Phys. 75, 473–541 (2003)

    ADS  CAS  Article  Google Scholar 

  6. Lee, W. S. et al. Abrupt onset of a second energy gap at the superconducting transition of underdoped Bi2212. Nature 450, 81–84 (2007)

    ADS  CAS  Article  Google Scholar 

  7. Valla, T., Fedorov, A. V., Lee, J., Davis, J. C. & Gu, G. D. The ground state of the pseudogap in cuprate superconductors. Science 314, 1914–1916 (2006)

    ADS  CAS  Article  Google Scholar 

  8. Tanaka, K. et al. Distinct Fermi-momentum-dependent energy gaps in deeply underdoped Bi2212. Science 314, 1910–1913 (2006)

    ADS  CAS  Article  Google Scholar 

  9. Kanigel, A. et al. Evolution of the pseudogap from Fermi arcs to the nodal liquid. Nature Phys. 2, 447–451 (2006)

    ADS  CAS  Article  Google Scholar 

  10. Norman, M. R. et al. Modeling the Fermi arc in underdoped cuprates. Phys. Rev. B 76, 174501 (2007)

    ADS  Article  Google Scholar 

  11. Norman, M. R. et al. Destruction of the Fermi surface in underdoped high-T c superconductors. Nature 392, 157–160 (1998)

    ADS  CAS  Article  Google Scholar 

  12. Kisker, E. et al. Evidence for the high-spin to low-spin state transition in ordered Fe3Pt Invar. Phys. Rev. Lett. 58, 1784–1787 (1987)

    ADS  CAS  Article  Google Scholar 

  13. Greber, T. et al. Photoemission above the Fermi level: the top of the minority d band in nickel. Phys. Rev. Lett. 79, 4465–4468 (1997)

    ADS  CAS  Article  Google Scholar 

  14. Matsui, H. et al. BCS-like Bogoliubov quasiparticles in high-T C superconductors observed by angle-resolved photoemission spectroscopy. Phys. Rev. Lett. 90, 217002 (2003)

    ADS  CAS  Article  Google Scholar 

  15. Lucy, L. B. An iterative technique for the rectification of observed distributions. Astron. J. 79, 745–754 (1974)

    ADS  Article  Google Scholar 

  16. Matsui, H. et al. Angle-resolved photoemission spectroscopy of the antiferromagnetic superconductor Nd1. 87Ce0. 13CuO4: anisotropic spin-correlation gap, pseudogap, and the induced quasiparticle mass enhancement. Phys. Rev. Lett. 94, 047005 (2005)

    ADS  CAS  Article  Google Scholar 

  17. Chakravarty, S. et al. Angle-resolved photoemission spectra in the cuprates from the d-density wave theory. Phys. Rev. B 68, 100504 (2003)

    ADS  Article  Google Scholar 

  18. Wen, X. G. & Lee, P. A. Theory of quasiparticles in the underdoped high-T C superconducting state. Phys. Rev. Lett. 80, 2193–2196 (1998)

    ADS  CAS  Article  Google Scholar 

  19. Konik, R. M., Rice, T. M. & Tsvelik, A. M. Doped spin liquid: Luttinger sum rule and low temperature order. Phys. Rev. Lett. 96, 086407 (2006)

    ADS  CAS  Article  Google Scholar 

  20. Yang, K. Y., Rice, T. M. & Zhang, F. C. Phenomenological theory of the pseudogap state. Phys. Rev. B 73, 174501 (2006)

    ADS  Article  Google Scholar 

  21. Xu, Z. A. et al. Vortex-like excitations and the onset of superconducting phase fluctuation in underdoped La2-x Sr x CuO4 . Nature 406, 486–488 (2000)

    ADS  CAS  Article  Google Scholar 

  22. Wang, Y. et al. Field-enhanced diamagnetism in the pseudogap state of the cuprate Bi2Sr2CaCu2O8+d superconductor in an intense magnetic field. Phys. Rev. Lett. 95, 247002 (2005)

    ADS  Article  Google Scholar 

  23. Wang, Y., Li, L. & Ong, N. P. Nernst effect in high-T C superconductors. Phys. Rev. B 73, 024510 (2006)

    ADS  Article  Google Scholar 

  24. Emery, V. J., Kivelson, S. A. & Zachar, O. Spin-gap proximity effect mechanism of high-temperature superconductivity. Phys. Rev. B 56, 6120–6147 (1997)

    ADS  CAS  Article  Google Scholar 

  25. Tsvelik, A. M. & Chubukov, A. V. Phenomenological theory of the underdoped phase of a high-T c superconductor. Phys. Rev. Lett. 98, 237001– (2007)

    ADS  CAS  Article  Google Scholar 

Download references

Acknowledgements

We thank S. Chakravarty, A. Chubukov, P. Lee, M. Norman, M. Rice, D. Scalapino and J. Tranquada for discussions. The assistance of J. Wen and Z. Xu with the preparation of underdoped crystals is also acknowledged. This work was supported by the US Department of Energy.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to P. D. Johnson.

Supplementary information

Supplementary Information

This file contains Supplementary Notes incorporating Supplementary Figures SI1and SI2 with Legends and Supplementary References. (PDF 696 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Yang, HB., Rameau, J., Johnson, P. et al. Emergence of preformed Cooper pairs from the doped Mott insulating state in Bi2Sr2CaCu2O8+δ. Nature 456, 77–80 (2008). https://doi.org/10.1038/nature07400

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature07400

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing