Superconducting Fluctuations in Overdoped Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}

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+δ} (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 (π,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.