Green Function Theory of Strongly Correlated Electron Systems

TL;DR

This paper develops a Green function approach to a generalized Hubbard model, revealing complex phases including antiferromagnetism and superconductivity in strongly correlated electron systems.

Contribution

It introduces a new effective Hamiltonian using Gutzwiller projection for better modeling of strongly correlated electrons.

Findings

The model predicts antiferromagnetic order at zero doping.

Superconductivity emerges at low temperatures in doped regions.

Phase diagram of antiferromagnetism and superconductivity is provided.

Abstract

A novel effective Hamiltonian in the subspace of singly occupied states is obtained by applying the Gutzwiller projection approach to a generalized Hubbard model with the interactions between two nearest- neighbor sites. This model provides a more complete description of the physics of strongly correlated electron systems. The system is not necessarily in a ferromagnetic state as temperature approaches zero at any doping level. The system, however, must be in an antiferromagnetic state at the origin of the doping-temperature plane. Moreover, the model exhibits superconductivity in a doped region at sufficiently low temperatures. We summarize the studies and provide a phase diagram of the antiferromagnetism and the superconductivity of the model in the doping-temperature plane here. Details will be presented in subsequent papers.