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 ${\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{CaCu}}_2{\mathrm{O}}_{8+\delta }$ ($T_c=66\mathrm{K}$) 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.

中文翻译：

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过掺杂Bi2Sr2CaCu2O8+δ中的超导波动

波动的超导性——材料电阻状态下的残留库珀配对——通常与低维数、强无序或低载流子密度有关。在这里，我们报告了重空穴掺杂的铜酸盐超导体中持续超导波动的单粒子光谱、热力学和磁学证据${双}_2{锶}_2{\mathrm{钙铜}}_2{\mathrm{哦}}_{8+\delta }$ (${吨}_C=66\mathrm{钾}$) 尽管载流子密度高。通过无符号问题的量子蒙特卡罗计算，我们展示了在$(\pi ,0)$可以帮助增强超导相位波动。最后，我们讨论了各向异性能带结构对过度掺杂铜酸盐和其他超导体的相位相干限制超导性的影响。