Doping dependence of phase coherence between superconducting Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ grains

TL;DR

This study investigates how doping levels affect phase coherence between superconducting Bi-2212 grains, revealing deviations from expected superfluid density behavior and suggesting the presence of competing orders and quantum critical points within the superconducting dome.

Contribution

It provides new experimental insights into the doping dependence of phase coherence and proposes the existence of quantum critical points in cuprate superconductors.

Findings

Deviations from superfluid density expectations in underdoped and overdoped regimes.

Evidence of competing orders influencing phase coherence.

Indications of two quantum critical points within the superconducting dome.

Abstract

In the present work, we report the new findings on the doping level dependence of the phase coherence between superconducting Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi-2212) grains. The experimental results from the strongly underdoped and overdoped regimes deviated from the expectation based on the doping level dependence of the superfluid density at $T$ = 0 K. These findings appear to be governed by interplay between competing orders inside the superconducting dome of cuprate superconductors. Two quantum critical points are likely to exist at the underdoped and overdoped regimes beneath the superconducting dome.