Role of pair-breaking and phase fluctuations in c-axis tunneling in underdoped Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$

TL;DR

This study investigates how disorder affects the c-axis supercurrent in underdoped Bi2212 superconductors, revealing that phase fluctuations and pair-breaking significantly influence the Josephson Plasma Resonance.

Contribution

It demonstrates that disorder reduces the Josephson plasma frequency proportionally to T_c and confirms a model where quantum phase fluctuations dominate in underdoped cuprates.

Findings

Josephson plasma frequency decreases with disorder

Temperature dependence remains unchanged with irradiation

Quantum phase fluctuations explain the observed behavior

Abstract

The Josephson Plasma Resonance is used to study the c-axis supercurrent in the superconducting state of underdoped Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ with varying degrees of controlled point-like disorder, introduced by high-energy electron irradiation. As disorder is increased, the Josephson Plasma frequency decreases proportionally to the critical temperature. The temperature dependence of the plasma frequency does not depend on the irradiation dose, and is in quantitative agreement with a model for quantum fluctuations of the superconducting phase in the CuO$_{2}$ layers.