Some Properties of the Spin-Polarized Attractive Hubbard Model

TL;DR

This paper investigates how a Zeeman magnetic field affects superconductivity in the attractive Hubbard model, revealing phase transitions, reentrant behavior, and gapless states through analysis of phase diagrams and the Hartree term.

Contribution

It provides new insights into the effects of magnetic fields on superconductivity within the attractive Hubbard model, including phase transition details and the role of the Hartree term.

Findings

Two critical magnetic fields for phase transition identified

Reentrant superconducting transition observed

Gapless superconductivity demonstrated

Abstract

The influence of a Zeeman magnetic field on the superconducting characteristics of the attractive Hubbard model was investigated. The ground state and temperature phase diagrams were obtained for a fixed number of particles. Two critical magnetic fields were found for the first order phase transition from the superconducting to the normal state for $n\neq 1$. For some range of parameters a reentrant transition was found and gapless superconductivity was obtained. The significance of the Hartree term was also analyzed.