Direct spectroscopic evidence for phase competition between the pseudogap and superconductivity in Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+{\delta}}$

TL;DR

This study provides direct spectroscopic evidence of phase competition between the pseudogap and superconductivity in Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+{eta}}$, revealing a singularity at $T_c$ across various doping levels, advancing understanding of high-$T_c$ cuprates.

Contribution

It offers the first direct spectroscopic evidence linking the pseudogap and superconductivity phases through a singularity at $T_c$, confirming phase competition in cuprates.

Findings

Spectroscopic singularity at $T_c$ indicates phase competition.

Competition persists up to high doping levels (~0.22).

Comparison with theory confirms the antagonistic relationship.

Abstract

In the high-temperature ($T_{c}$) cuprate superconductors, increasing evidence suggests that the pseudogap, existing below the pseudogap temperature $T$*, has a distinct broken electronic symmetry from that of superconductivity. Particularly, recent scattering experiments on the underdoped cuprates have suggested that a charge ordering competes with superconductivity. However, no direct link of this physics and the important low-energy excitations has been identified. Here we report an antagonistic singularity at $T_{c}$ in the spectral weight of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+{\delta}}$ as a compelling evidence for phase competition, which persists up to a high hole concentration $p$ ~ 0.22. Comparison with a theoretical calculation confirms that the singularity is a signature of competition between the order parameters for the pseudogap and superconductivity. The observation of the spectroscopic singularity at finite temperatures over a wide doping range provides new insights into the nature of the competitive interplay between the two intertwined phases and the complex phase diagram near the pseudogap critical point.