Coexistence of the superconducting energy gap and pseudogap above and below the transition temperature of superconducting cuprates

TL;DR

This paper models the superconducting gap in cuprates, showing that both the superconducting gap and pseudogap coexist above and below the transition temperature, reconciling conflicting views on pseudogap physics.

Contribution

It provides a thermodynamic expression for the superconducting gap in s- and d-wave symmetries and demonstrates the persistence of the gap above T_c due to fluctuations.

Findings

Superconducting gap persists above T_c due to fluctuations.

Two gaps, the superconducting gap and pseudogap, coexist above T_c.

Reconciles conflicting theories on pseudogap physics.

Abstract

We express the superconducting gap, $\Delta(T)$, in terms of thermodynamic functions in both $s$- and d-wave symmetries. Applying to Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ and Y$_{0.8}$Ca$_{0.2}$Ba$_2$Cu$_3$O$_{7-\delta}$ we find that for all dopings $\Delta(T)$ persists, as a partial gap, high above $T_c$ due to strong superconducting fluctuations. Therefore in general two gaps are present above $T_c$, the superconducting gap and the pseudogap, effectively reconciling two highly polarized views concerning pseudogap physics.