Inhomogeneous D-Wave Superconductivity and Antiferromagnetism in a Two-Dimensional Extended Hubbard Model with Nearest-Neighbor Attractive Interaction

TL;DR

This study investigates how inhomogeneous phases of d-wave superconductivity and antiferromagnetism emerge in a two-dimensional extended Hubbard model with attractive interactions, highlighting the system's sensitivity to impurities and external perturbations.

Contribution

It demonstrates that the extended Hubbard model exhibits phase separation and inhomogeneity in order parameters, providing insights into cuprate superconductor behavior.

Findings

Phase separation occurs in the model without impurities.

Inhomogeneous order parameters are stabilized by weak impurities.

Results suggest relevance to inhomogeneous cuprate superconductors.

Abstract

To understand the interplay of d-wave superconductivity and antiferromagnetism, we consider a two-dimensional extended Hubbard model with nearest neighbor attractive interaction. The Hamiltonian is solved in the mean-field approximation on a finite lattice. In the impurity-free case, the minimum energy solutions show phase separation as predicted previously based on free energy argument. The phase separation tendency implies that the system can be easily rendered inhomogeneous by a small external perturbation. Explicit solutions of a model including weak impurity potentials are indeed inhomogeneous in the spin-density-wave and d-wave pairing order parameters. Relevance of the results to the inhomogeneous cuprate superconductors is discussed.