Correlation Effects and Non-Collinear Magnetism in the Doped Hubbard Model

TL;DR

This paper investigates how electron correlations influence magnetic phases in the doped Hubbard model, revealing that correlations suppress spiral and ferromagnetic states and highlighting the importance of phase separation near half-filling.

Contribution

It provides a comprehensive analysis of magnetic phase stability in the doped Hubbard model, including correlation effects and phase separation, which were often overlooked in previous studies.

Findings

Correlation effects suppress spiral and ferromagnetic states.

Electronic phase separation is significant near half-filling.

Magnetic ordering varies across different cubic lattices.

Abstract

The ground--state magnetic phase diagram is investigated for the two-- and three--dimensional $t$--$t'$ Hubbard model. We take into account commensurate ferro--, antiferromagnetic, and incommensurate (spiral) magnetic phases, as well as phase separation into magnetic phases of different types, which was often missed in previous investigations. We trace the influence of correlation effects on the stability of both spiral and collinear magnetic order by comparing the results of employing both the generalized non-correlated mean--field (Hartree--Fock) approximation and generalized slave boson approach by Kotliar and Ruckenstein with correlation effects included. We found that the spiral states and especially ferromagnetism are generally strongly suppressed up to non-realistic large Hubbard $U$, if the correlation effects are taken into account. The electronic phase separation plays an important role in the formation of magnetic states and corresponding regions are wide, especially in the vicinity of half--filling. The details of magnetic ordering for different cubic lattices are discussed.