Evidence of precursor superconductivity as high as 180 K from infrared spectroscopy

TL;DR

This study uses infrared spectroscopy to identify a precursor superconducting state in cuprates that appears as high as 180 K, well above the critical temperature, revealing new insights into high-temperature superconductivity.

Contribution

It provides evidence of precursor superconductivity at temperatures up to 180 K in underdoped cuprates, using multilayer infrared response analysis.

Findings

Precursor superconducting state exists above Tc.

Tons reaches up to ~180 K in underdoped samples.

Magnetic field data support the precursor state evidence.

Abstract

We show that a multilayer analysis of the infrared c-axis response of RBa2Cu3O7-d (R=Y, Gd, Eu) provides important new information about the anomalous normal state properties of underdoped cuprate high temperature superconductors. Besides competing correlations which give rise to a pseudogap that depletes the low-energy electronic states below T*>>Tc, it enables us to identify the onset of a precursor superconducting state below Tons>Tc. We map out the doping phase diagram of Tons which reaches a maximum of ~180 K at strong underdoping and present magnetic field dependent data which confirm our conclusions.