"Spin-Disentangled" Exact Diagonalization of Repulsive Hubbard Systems: Superconducting Pair Propagation

TL;DR

This paper introduces a novel exact diagonalization method for Hubbard systems that reveals how bound pairs propagate superconductingly between clusters, providing insights into high-temperature superconductivity in cuprates.

Contribution

The paper presents a new exact diagonalization technique that reduces computational complexity and demonstrates superconducting pair propagation in Hubbard models of cuprates.

Findings

Bound pairs propagate in a superconducting manner between clusters.

The method handles matrices based on fermion configurations per spin.

Numerical results support a new analytic scheme for pair propagation and flux quantization.

Abstract

By a novel exact diagonalization technique we show that bound pairs propagate between repulsive Hubbard clusters in a superconducting fashion. The size of the matrices that must be handled depends on the number of fermion configurations {\em per spin}, which is of the order of the square root of the overall size of the Hilbert space. We use CuO$_{4}$ units connected by weak O-O links to model interplanar coupling and c-axis superconductivity in Cuprates. The numerical evidence on Cu$_{2}$O$_{8}$ and Cu$_{3}$O$_{12}$ prompts a new analytic scheme describing the propagation of bound pairs and also the superconducting flux quantization in a 3-d geometry.