Superconductivity in electron-doped cuprates: Gap shape change and symmetry crossover with doping

TL;DR

This paper investigates how the superconducting gap symmetry and shape evolve with doping in electron-doped cuprates, revealing a transition from d_{x^2-y^2} to d_{xy} symmetry and aligning with experimental observations.

Contribution

It models the doping-dependent symmetry crossover and gap shape change in electron-doped cuprates using the Kohn-Luttinger mechanism, providing theoretical insight into experimental findings.

Findings

Superconducting gap remains d_{x^2-y^2} over a large doping range.

The gap maximum shifts away from (pi,0) with doping.

A crossover to d_{xy} symmetry occurs as doping increases.

Abstract

The Kohn-Luttinger mechanism for superconductivity is investigated in a model for the electron doped cuprates. The symmetry of the order parameter of the superconducting phase is determined as a function of the geometry of the Fermi surface together with the structure of the electron-hole susceptibility. It is found to remain d_{x^2-y^2} wave within a large doping range. The shape of the gap anisotropy evolves with doping, with the maximum gap moving away from (pi ,0), in good agreement with recent experiments. As the shift of the maximum increases, a crossover to d_{xy}-symmetry is found.