Engineering Hubbard models with gated two-dimensional moir\'e systems

TL;DR

This paper proposes using gated two-dimensional moiré systems to simulate Hubbard models, demonstrating tunable ground states with various magnetic orders and outlining experimental pathways for realization.

Contribution

It introduces a method to realize and control lattice Hubbard models in moiré systems by adjusting gate separation and potential depth, connecting theory with experimental feasibility.

Findings

Tunable ground states with stripe, antiferromagnetic, ferromagnetic, and paramagnetic phases.

Control of magnetic order through gate separation and moiré potential.

Comparison of square and triangular moiré systems for experimental implementation.

Abstract

Lattice models are powerful tools for studying strongly correlated quantum many-body systems, but their general lack of exact solutions motivates efforts to simulate them in tunable platforms. Recently, a promising new candidate has emerged for such platforms from two-dimensional materials. A subset of moir\'e systems can be effectively described as a two-dimensional electron gas (2D EG) subject to a moir\'e potential, with electron-electron interactions screened by nearby metallic gates. In this paper, we investigate the realization of lattice models in such systems. We show that, by controlling the gate separation, a 2D EG in a square moir\'e potential can be systematically tuned into a system whose ground state exhibits orders analogous to those of the square lattice Hubbard model, including the stripe phase. Furthermore, we study how variations in gate separation and moir\'e potential depth affect the ground-state orders. A number of antiferromagnetic phases, as well as a ferromagnetic phase and a paramagnetic phase, are identified. We then apply our quantitative downfolding approach to triangular moir\'e systems closer to current experimental conditions, compare them with the square lattice parameters studied, and outline routes for experimental realization of the phases.