Weak phase stiffness and nature of the quantum critical point in underdoped cuprates

TL;DR

This paper models the zero-temperature phase diagram of underdoped cuprates using experimental spectral data, revealing a quantum critical point characterized by diverging pair mass and suppressed superfluidity.

Contribution

It provides a quantitative strong-binding limit model of cuprate superconductivity based solely on experimental spectral functions, identifying a quantum critical point with diverging pair mass.

Findings

Superconductivity arises above critical doping due to kinetic effects.

Complete loss of superfluidity below critical doping from local quantum fluctuations.

Predicted mass divergence at the quantum critical point.

Abstract

We demonstrate that the zero-temperature superconducting phase diagram of underdoped cuprates can be quantitatively understood in the strong binding limit, using only the experimental spectral function of the "normal" pseudo-gap phase without any free parameter. In the prototypical (La$_{1-x}$Sr$_x$)$_2$CuO$_4$, a kinetics-driven $d$-wave superconductivity is obtained above the critical doping $\delta_c\sim 5.2\%$, below which complete loss of superfluidity results from local quantum fluctuation involving local $p$-wave pairs. Near the critical doping, a enormous mass enhancement of the local pairs is found responsible for the observed rapid decrease of phase stiffness. Finally, a striking mass divergence is predicted at $\delta_c$ that dictates the occurrence of the observed quantum critical point and the abrupt suppression of the Nernst effects in the nearby region.