Incommensurate magnetic order and phase separation in the two-dimensional Hubbard model with nearest and next-nearest neighbor hopping

TL;DR

This study maps the magnetic phases of the 2D Hubbard model with complex hopping, revealing phase separation and incommensurate order, which could explain magnetic behaviors in cuprates and ruthenates.

Contribution

It provides a detailed phase diagram including incommensurate and phase-separated states, highlighting the importance of phase separation in understanding magnetic properties.

Findings

First-order transitions lead to phase separation between magnetic phases.

Phase separation significantly affects the phase diagram near half-filling.

Results suggest magnetic phase coexistence explains behaviors in cuprates and ruthenates.

Abstract

We consider the ground state magnetic phase diagram of the two-dimensional Hubbard model with nearest and next-nearest neighbor hopping in terms of electronic density and interaction. We treat commensurate ferro- and antiferromagnetic, as well as incommensurate (spiral) magnetic phases. The first-order magnetic transitions with changing chemical potential, resulting in a phase separation (PS) in terms of density, are found between ferromagnetic, antiferromagnetic and spiral magnetic phases. We argue that the account of PS has a dramatic influence on the phase diagram in the vicinity of half-filling. The results imply possible interpretation of the unusual behavior of magnetic properties of one-layer cuprates in terms of PS between collinear and spiral magnetic phases. The relation of the results obtained to the magnetic properties of ruthenates is also discussed.