Interplay of magnetism and superconductivity in 2D extended Hubbard model

TL;DR

This paper investigates how magnetism and superconductivity coexist and compete in a 2D extended Hubbard model, revealing phase separation and coexistence phenomena through theoretical approximations.

Contribution

It introduces a comprehensive analysis of magnetic and superconducting states, including intermediate symmetries and phase separation, using Hartree-Fock and slave boson methods.

Findings

Coexistence of magnetic and superconducting phases under certain conditions

Identification of phase separation between different states

Comparison of correlation effects via different theoretical approaches

Abstract

The interplay between magnetic and superconducting states on a square lattice is studied using the extended Hubbard model, which takes into account the attraction of electrons located at nearest neighbor sites. Ferro-, antiferro-, and spiral magnetic states with all possible sets of spiral wave vectors, as well as singlet superconducting states with s-wave and d-wave pairing order parameters, are considered. Formation of a state with the intermediate s+id-symmetry and phase separation between different phases are allowed. The results of the Hartree-Fock and slave boson approximations are compared in order to study the role of correlation effects. Both macroscopic phase separation and microscopic coexistence of the superconducting and magnetic phases are found under certain model parameters.