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Abrupt onset of a second energy gap at the superconducting transition of underdoped Bi2212

Nature volume 450, pages 81–84 (2007)Cite this article

Abstract

The superconducting gap—an energy scale tied to the superconducting phenomena—opens on the Fermi surface at the superconducting transition temperature (Tc) in conventional BCS superconductors. In underdoped high-Tc superconducting copper oxides, a pseudogap (whose relation to the superconducting gap remains a mystery) develops well above Tc (refs 1, 2). Whether the pseudogap is a distinct phenomenon or the incoherent continuation of the superconducting gap above Tc is one of the central questions in high-Tc research3,4,5,6,7,8. Although some experimental evidence suggests that the two gaps are distinct9,10,11,12,13,14,15,16,17,18, this issue is still under intense debate. A crucial piece of evidence to firmly establish this two-gap picture is still missing: a direct and unambiguous observation of a single-particle gap tied to the superconducting transition as function of temperature. Here we report the discovery of such an energy gap in underdoped Bi2Sr2CaCu2O8+δ in the momentum space region overlooked in previous measurements. Near the diagonal of Cu–O bond direction (nodal direction), we found a gap that opens at Tc and has a canonical (BCS-like) temperature dependence accompanied by the appearance of the so-called Bogoliubov quasi-particles, a classical signature of superconductivity. This is in sharp contrast to the pseudogap near the Cu–O bond direction (antinodal region) measured in earlier experiments19,20,21.

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Figure 1: Temperature and momentum dependence of the low energy excitations in slightly underdoped Bi2212 ( T c = 92 K).
Figure 2: Detailed temperature dependence of the superconducting gap near the nodal region of underdoped Bi2212 ( T c = 92 K) measured under two different experimental configurations.
Figure 3: Temperature dependence of the gap profile.
Figure 4: Schematic illustrations of the gap function evolution for three different doping levels.

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References

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

    Article  CAS  ADS  Google Scholar 

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

    Article  CAS  ADS  Google Scholar 

  3. Emery, V. J. & Kivelson, S. A. Importance of phase fluctuations in superconductors with small superfluid density. Nature 374, 434–437 (1995)

    Article  CAS  ADS  Google Scholar 

  4. Wen, X. G. & Lee, P. A. Theory of underdoped cuprates. Phys. Rev. Lett. 76, 503–506 (1996)

    Article  CAS  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  6. Benfatto, L., Caprara, S. & DiCastro, C. Gap and pseudogap evolution within the charge-ordering scenario for superconducting cuprates. Eur. Phys. J. B 17, 95–102 (2000)

    Article  CAS  ADS  Google Scholar 

  7. Li, J.-X., Wu, C.-Q. & Lee, D.-H. Checkerboard charge density wave and pseudogap of high-T C cuprate. Phys. Rev. B 74, 184515 (2006)

    Article  ADS  Google Scholar 

  8. Millis, A. J. Gaps and our understanding. Science 314, 1888–1889 (2006)

    Article  CAS  Google Scholar 

  9. Opel, M. et al. Carrier relaxation, pseudogap, and superconducting gap in high-T C cuprates: A Raman scattering study. Phys. Rev. B 61, 9752–9774 (2000)

    Article  CAS  ADS  Google Scholar 

  10. Le Tacon, M. et al. Two energy scales and two distinct quasiparticle dynamics in the superconducting state of underdoped cuprates. Nature Phys. 2, 537–543 (2006)

    Article  CAS  ADS  Google Scholar 

  11. Deutscher, G. Coherence and single-particle excitations in the high-temperature superconductors. Nature 397, 410–412 (1999)

    Article  CAS  ADS  Google Scholar 

  12. Svistunov, V. M., Tarenkov, V., Yu, D’Yachenko, A. I. & Hatta, E. Temperature dependence of the energy gap in Bi2223 metal oxide superconductor. JETP Lett. 71, 289–292 (2000)

    Article  CAS  ADS  Google Scholar 

  13. Krasnov, V. M., Yurgens, A., Winkler, D., Delsing, P. & Claeson, T. Evidence of coexistence of the superconducting gap and pseudogap in Bi-2212 from intrinsic tunnelling spectroscopy. Phys. Rev. Lett. 84, 5860–5863 (2000)

    Article  CAS  ADS  Google Scholar 

  14. Demsar, J., Hudej, R., Karpinski, J., Kabanov, V. V. & Mihailovic, D. Quasiparticle dynamics and gap structure in HgBa2Ca2Cu3O8+δ investigated with femtosecond spectroscopy. Phys. Rev. B 63, 054519 (2001)

    Article  ADS  Google Scholar 

  15. Gomes, K. K. et al. Visualizing pair formation on the atomic scale in the high-T c superconductor Bi2Sr2CaCu2O8+δ . Nature 447, 569–572 (2007)

    Article  CAS  ADS  Google Scholar 

  16. Boyer, M. C. et al. Imaging the two gaps of the high-temperature superconductor Bi2Sr2CuO6+x . Nature Phys. doi:10.1038/nphys725. (in the press)

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

    Article  CAS  ADS  Google Scholar 

  18. Kondo, T. et al. Evidence for two energy scales in the superconducting state of optimally doped (Bi,Pb)2(Sr,La)2CuO6+δ . Phys. Rev. Lett. 98, 267004 (2007)

    Article  ADS  Google Scholar 

  19. Loeser, A. G. et al. Excitation gap in the normal state of underdoped Bi2Sr2CaCu2O8+δ . Science 273, 325–329 (1996)

    Article  CAS  ADS  Google Scholar 

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

    Article  CAS  ADS  Google Scholar 

  21. Loeser, A. G. et al. Temperature and doping dependence of the Bi–Sr–Ca–Cu–O electronic structure and fluctuation effects. Phys. Rev. B 56, 14185–14189 (1997)

    Article  CAS  ADS  Google Scholar 

  22. Renner, Revaz, B., Genoud, J.-Y., Kadowaki, K. & Fischer, O. Pseudogap precursor of the superconducting gap in under- and overdoped Bi2Sr2CaCu2O8+δ . Phys. Rev. Lett. 80, 149–152 (1998)

    Article  CAS  ADS  Google Scholar 

  23. Norman, M. R., Randeria, M., Ding, H. & Campuzano, J. C. Phenomenology of the low-energy spectral function in high-T C superconductors. Phys. Rev. B 57, R11093–R11096 (1998)

    Article  CAS  ADS  Google Scholar 

  24. Hosseini, A. Microwave spectroscopy of thermally excited quasiparticle in YBa2Cu3O6. 99 . Phys. Rev. B 60, 1349–1359 (1999)

    Article  CAS  ADS  Google Scholar 

  25. Krishana, K., Harris, J. M. & Ong, N. P. Quasiparticle mean free path in YBa2Cu3O7 measured by the thermal Hall conductivity. Phys. Rev. Lett. 75, 3529–3532 (1995)

    Article  CAS  ADS  Google Scholar 

  26. Valla, T. et al. Fine details of the nodal electronic excitations in Bi2Sr2CaCu2O8+δ . Phys. Rev. B 73, 184518 (2006)

    Article  ADS  Google Scholar 

  27. Yamasaki, T. et al. Unmasking the nodal quasiparticle dynamics in cuprate superconductors using low-energy photoemission. Phys. Rev. B 75, 140513 (2007)

    Article  ADS  Google Scholar 

  28. Alexandrov, A. S. & Andreev, A. F. Gap and subgap tunneling in cuprates. Preprint at arXiv:cond-mat/0005315v3 [cond-mat.supr-con]

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Acknowledgements

We thank R. Moore for experimental assistance, and D. J. Scalapino, S. Kivelson and T. K. Lee for helpful discussions. This work is supported by the DOE Office of Basic Energy Science, Division of Materials Science and Engineering, and the National Science Foundation. ARPES experiments were performed at the Stanford Synchrotron Radiation Laboratory (SSRL), which is operated by the Department of Energy Office of Basic Energy Science.

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Authors and Affiliations

  1. Department of Physics, Applied Physics, and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California 94305, USA,

    W. S. Lee, I. M. Vishik, K. Tanaka, D. H. Lu, T. Sasagawa & Z.-X. Shen

  2. Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California 94720, USA ,

    K. Tanaka & Z. Hussain

  3. Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan,

    N. Nagaosa

  4. Department of Physics, University of Waterloo, Ontario N2L 3G1, Canada

    T. P. Devereaux

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  1. W. S. Lee
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Correspondence to W. S. Lee or Z.-X. Shen.

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This file contains Supplementary Methods, Supplementary Figures S1-S3 with Legends and Supplementary Discussion. (PDF 333 kb)

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Lee, W., Vishik, I., Tanaka, K. et al. Abrupt onset of a second energy gap at the superconducting transition of underdoped Bi2212. Nature 450, 81–84 (2007). https://doi.org/10.1038/nature06219

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