Electronic crossover suggested by Raman scattering in overdoped (Y,Ca)Ba2Cu3Oy

TL;DR

This study uses Raman scattering to identify an electronic crossover in overdoped (Y,Ca)Ba2Cu3Oy, linked to pseudogap collapse, revealing significant changes in superconducting responses at a critical doping level.

Contribution

It provides experimental evidence of an electronic crossover associated with pseudogap collapse in overdoped cuprates using Raman scattering.

Findings

Superconducting pair-breaking peaks change at doping p=0.19.

Anisotropy in Raman spectra varies significantly at the crossover.

Resistivity data support pseudogap closure around p=0.18.

Abstract

The electronic Raman scattering in overdoped (Y,Ca)Ba2Cu3Oy was investigated with changing hole concentration in the superconducting state. It was found that the superconducting responses such as the pair-breaking peaks in the A1g and B1g spectra and the anisotropy of the pair-breaking peak in XX and YY polarizations radically change at around the carrier doping p=0.19. Since both a- and c-axis resistivities strongly suggest the closing of pseudogap at p~0.18, the observed change at p=0.19 in superconducting Raman response is attributed to the electronic crossover due to the collapse of the pseudogap.