Zero-temperature Phase Diagram of Two Dimensional Hubbard Model

TL;DR

This study maps the zero-temperature phase diagram of the 2D Hubbard model on a triangular lattice, revealing the competition between metallic, magnetic, and non-magnetic states using a self-energy functional approach.

Contribution

It provides the first detailed zero-temperature phase diagram for the anisotropic 2D Hubbard model on a triangular lattice, highlighting the stability of magnetic and non-magnetic states.

Findings

Non-magnetic Mott insulator is not the ground state but a meta-stable state.

Magnetic states with $( ext{pi}, ext{pi})$ and $(2 ext{pi}/3, 2 ext{pi}/3)$ structures compete with metallic states.

The phase diagram shows the stability regions of different magnetic orders and metallic phases.

Abstract

We investigate the two-dimensional Hubbard model on the triangular lattice with anisotropic hopping integrals at half filling. By means of a self-energy functional approach, we discuss how stable the non-magnetic state is against magnetically ordered states in the system. We present the zero-temperature phase diagram, where the normal metallic state competes with magnetically ordered states with $(\pi, \pi)$ and $(2\pi/3, 2\pi/3)$ structures. It is shown that a non-magnetic Mott insulating state is not realized as the ground state, in the present framework, but as a meta-stable state near the magnetically ordered phase with $(2\pi/3, 2\pi/3)$ structure.