Crossover behavior for complex order parameter in high-Tc superconductors

TL;DR

This paper introduces a new method to analyze how complex order parameters in high-Tc superconductors compete by varying the attractive potential, explaining experimental results and linking to microscopic models like spin fluctuation theory.

Contribution

It presents a novel approach to study complex order parameter mixtures in high-Tc superconductors by adjusting the potential position in a 2D extended Hubbard model, connecting theory with experiments.

Findings

Optimal s-component peak varies with potential position parameter.

d-component peaks around hole content 0.39.

Method explains several experimental observations.

Abstract

A number of recent experiments have suggested the presence of either real or complex components in the gap symmetry of high-$T_c$ superconductors (HTSC). In this paper we introduce a novel approach to study the competition of such complex order parameter mixtures by varying the position of the two-body attractive potential in a two dimensional extended Hubbard Hamiltonian. We show that this procedure explain a number of experimental results and on the theoretical side, it may be related with certain HTSC microscopic models like the spin fluctuation theory. Following current trends we concentrate on the study of $d_{x^2-y^2}$ order parameter with a component of the type $d_{xy}$ or a s-wave like $s_{x^2+y^2}$ and $s_{xy}$ symmetry. We show that the position of the optimal s-component peak changes with the position parameter $b$ while the d-component occurs always in the optimally region around hole content $\rho \approx 0.39$.