Gap anisotropy and universal pairing scale in a spin fluctuation model for cuprates

TL;DR

This paper studies how d-wave pairing mediated by spin fluctuations evolves with coupling strength in cuprates, revealing a maximum pairing temperature at intermediate coupling and effects on gap anisotropy.

Contribution

It demonstrates the continuous evolution of the pairing temperature from weak to strong coupling and shows that pairing remains near the Fermi surface across all regimes.

Findings

T* peaks at intermediate coupling, reaching about J

Thermal spin fluctuations modestly reduce T*

Gap anisotropy is largest at weak coupling

Abstract

We consider the evolution of d-wave pairing, mediated by nearly critical spin fluctuations, with the coupling strength. We show that the onset temperature for pairing, T*, smoothly evolves between weak and strong coupling, passing through a broad maximum at intermediate coupling. At strong coupling, T* is of order the magnetic exchange energy J. We argue that for all couplings, pairing is confined to the vicinity of the Fermi surface. We also find that thermal spin fluctuations only modestly reduce T*, even at criticality, but they substantially smooth the gap anisotropy. The latter evolves with coupling, being the largest at weak coupling.