Respective influences of pair breaking and phase fluctuations in disordered high Tc superconductors

TL;DR

This study investigates how disorder affects superconductivity in cuprates, revealing that phase fluctuations, rather than pair breaking, dominate Tc suppression at high defect levels.

Contribution

It provides experimental evidence showing phase fluctuations play a significant role in Tc suppression in disordered high-Tc superconductors, challenging traditional pair-breaking theories.

Findings

Tc decrease does not follow pair-breaking expectations.

Phase fluctuations become dominant at high defect levels.

Results suggest new perspectives on disorder effects in cuprates.

Abstract

Electron irradiation has been used to introduce point defects in a controlled way in the CuO2 planes of underdoped and optimally doped YBCO. This technique allows us to perform very accurate measurements of Tc and of the residual resistivity in a wide range of defect contents xd down to Tc=0. The Tc decrease does not follow the variation expected from pair breaking theories. The evolutions of Tc and of the transition width with xd emphasize the importance of phase fluctuations, at least for the highly damaged regime. These results open new questions about the evolution of the defect induced Tc depression over the phase diagram of the cuprates