Quasi-point versus point nodes in $Sr_2RuO_4$, the case of a flat tight binding $\gamma$ sheet

TL;DR

This study investigates the nature of nodes in the superconducting gap of Sr2RuO4 using a tight-binding model, revealing conditions under which point or quasi-point nodes appear on the gamma Fermi surface sheet.

Contribution

It introduces a numerical tight-binding approach to analyze the node structure in Sr2RuO4, distinguishing between point and quasi-point nodes based on dispersion.

Findings

Identifies 4 point nodes in the flat gamma sheet limit.

Finds 4 quasi-point nodes in the strongly dispersive gamma sheet limit.

Provides a probabilistic framework explaining quasiparticle and Cooper pair distributions.

Abstract

We perform a numerical study of the unitary regime as a function of disorder concentration in the imaginary part of the elastic scattering cross-section for the compound $Sr_2RuO_4$ in the flat band non-disperse limit. By using a self-consistent tight-binding (TB) method, we find a couple of families of Wigner probabilistic functions that help to explain macroscopically the distribution between Fermion dressed quasiparticles and Cooper pairs, and also the position of nodes in the order parameter for $Sr_2RuO_4$. Therefore, we are able to show that a TB model for the $\gamma$ sheet numerically shows 4 point nodes in a flat $\gamma$ sheet limit or 4 quasi-point nodes for strong dispersion $\gamma$ sheet limit in the reduced phase scattering space (RPS).