Pairing Gaps, Pseudogaps, and Phase Diagrams for Cuprate Superconductors

TL;DR

This paper develops a generalized BCS theory incorporating non-zero momentum and angular momentum Cooper pairs, solving gap equations to produce phase diagrams that align with observed pseudogap phenomena in cuprate superconductors.

Contribution

It introduces a symmetry-constrained variational method to extend BCS theory, providing a unified framework for understanding the complex phase diagram of cuprate superconductors.

Findings

Pseudogap terminates at a critical doping level.

The model reproduces observed gap and phase structures.

Suggests pseudogap arises from competing order or preformed pairs.

Abstract

We use a symmetry-constrained variational procedure to construct a generalization of BCS to include Cooper pairs with non-zero momentum and angular momentum. The resulting gap equations are solved at zero and finite temperature, and the doping-dependent solutions are used to construct gap and phase diagrams. We find a pseudogap terminating at a critical doping that may be interpreted in terms of both competing order and preformed pairs. The strong similarity between observation and predicted gap and phase structure suggests that this approach may provide a unified description of the complex structure observed for cuprate superconductors.