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Open Access Publications from the University of California

Rapid change of superconductivity and electron-phonon coupling through critical doping in Bi-2212.

  • Author(s): He, Y
  • Hashimoto, M
  • Song, D
  • Chen, S-D
  • He, J
  • Vishik, IM
  • Moritz, B
  • Lee, D-H
  • Nagaosa, N
  • Zaanen, J
  • Devereaux, TP
  • Yoshida, Y
  • Eisaki, H
  • Lu, DH
  • Shen, Z-X
  • et al.

Electron-boson coupling plays a key role in superconductivity for many systems. However, in copper-based high-critical temperature (T c) superconductors, its relation to superconductivity remains controversial despite strong spectroscopic fingerprints. In this study, we used angle-resolved photoemission spectroscopy to find a pronounced correlation between the superconducting gap and the bosonic coupling strength near the Brillouin zone boundary in Bi2Sr2CaCu2O8+δ The bosonic coupling strength rapidly increases from the overdoped Fermi liquid regime to the optimally doped strange metal, concomitant with the quadrupled superconducting gap and the doubled gap-to-T c ratio across the pseudogap boundary. This synchronized lattice and electronic response suggests that the effects of electronic interaction and the electron-phonon coupling (EPC) reinforce each other in a positive-feedback loop upon entering the strange-metal regime, which in turn drives a stronger superconductivity.

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