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Yu He, Su-Di Chen, Zixiang Li, Dan Zhao, Dongjoon Song, Yoshiyuki Yoshida, Hiroshi Eisaki, Tao Wu, Xianhui Chen, Dong-Hui Lu, C. Meingast, Thomas Devereaux, R. J. Birgeneau, Makoto Hashimoto, Dung‐Hai Lee, Zhi‐Xun Shen
Abstract
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 Bi 2 Sr 2 CaCu 2 O 8 (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 ; 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.