Orthorhombicity mixing of s- and d- gap components in $YBa_2Cu_3O_7$ without involving the chains

TL;DR

This paper explores how momentum decoupling influences the mixing of s- and d-wave components in the superconducting gap of YBa2Cu3O7, showing that plane distortions can explain experimental s-wave mixing without involving chains.

Contribution

It demonstrates that plane distortions alone can account for s- and d-wave mixing in YBa2Cu3O7 without chain involvement, within the momentum decoupling framework.

Findings

Plane distortions explain s-wave mixing in YBa2Cu3O7.

Momentum decoupling leads to anisotropic superconductivity.

Chain involvement is necessary if pairing is mediated by spin fluctuations.

Abstract

Momentum decoupling develops when forward scattering dominates the pairing interaction and implies tendency for decorrelation between the physical behavior in the various regions of the Fermi surface. In this regime it is possible to obtain anisotropic s- or d-wave superconductivity even with isotropic pairing scattering. We show that in the momentum decoupling regime the distortion of the $CuO_2$ planes is enough to explain the experimental reports for s- mixing in the dominantly d-wave gap of $YBa_2Cu_3O_7$. In the case of spin fluctuations mediated pairing instead, a large part of the condensate must be located in the chains in order to understand the experiments.