Temperature evolution of correlation strength in the superconducting state of high-Tc cuprates

TL;DR

This study uses angle-resolved photoemission to examine how correlation strength evolves with temperature in high-Tc cuprates, revealing a reduction in electron correlations as the material transitions into the superconducting state.

Contribution

It provides direct experimental evidence of temperature-dependent correlation strength changes in high-Tc cuprates using ARPES measurements.

Findings

Spectral weight Z increases as temperature decreases below Tc.

Nodal spectral weight remains large above Tc.

Correlation strength reduces in the superconducting state.

Abstract

We have performed an angle-resolved photoemission study of the nodal quasi-particle spectra of the high-Tc cuprate tri-layer Bi2Sr2Ca2Cu3O10+d (Tc~ 110 K). The spectral weight Z of the nodal quasi-particle increases with decreasing temperature across the Tc. Such a temperature dependence is qualitatively similar to that of the coherence peak intensity in the anti nodal region of various high-Tc cuprates although the nodal spectral weight remains finite and large above Tc. We attribute this observation to the reduction of electron correlation strength in going from the normal metallic state to the superconducting state, a characteristic behavior of a superconductor with strong electron correlation.