Superconducting Fluctuations in Overdoped Bi2Sr2CaCu2O8+δ

Fluctuating superconductivity-vestigial Cooper pairing in the resistive state of a material-is usually associated with low dimensionality, strong disorder, or low carrier density. Here, we report single-particle spectroscopic, thermodynamic and magnetic evidence for persistent superconducting fluctuations in the heavily hole-doped cuprate superconductor Bi2Sr2CaCu2O8+delta (T-c = 66 K) despite the high carrier density. With a sign-problem-free quantum Monte Carlo calculation, we show how a partially flat band at (pi, 0) can help enhance superconducting phase fluctuations. Finally, we discuss the implications of an anisotropic band structure on the phase-coherence-limited superconductivity in overdoped cuprates and other superconductors.

Automated summary

Fluctuating superconductivity, characterized by vestigial Cooper pairing in the resistive state of a material, is often associated with low dimensionality, strong disorder, or low carrier density. However, this study shows persistent superconducting fluctuations in heavily hole-doped cuprate superconductor, Bi2Sr2CaCu2O8+delta, despite high carrier density. The research also suggests that a partially flat band at (pi, 0) may enhance superconducting phase fluctuations, and discusses the implications of an anisotropic band structure on phase-coherence-limited superconductivity in overdoped cuprates and other superconductors.