Local and nonlocal electronic correlations at the metal-insulator transition in the Hubbard model in two dimensions

TL;DR

This paper investigates the metal-insulator transition in the two-dimensional Hubbard model, revealing how local and nonlocal electronic correlations interplay across different coupling regimes using advanced many-body techniques.

Contribution

It introduces a non-perturbative approach to distinguish between Slater and Heisenberg regimes and characterizes the crossover region in the phase diagram.

Findings

Identification of Slater and Heisenberg regimes

Discovery of a crossover region with competing correlations

Insights into the formation of the insulating state

Abstract

Elucidating the physics of the single-orbital Hubbard model in its intermediate coupling regime is a key missing ingredient to our understanding of metal-insulator transitions in real materials. Using recent non-perturbative many-body techniques that are able to interpolate between the spin-fluctuation-dominated Slater regime at weak coupling and the Mott insulator at strong-coupling, we obtain the momentum-resolved spectral function in the intermediate regime and disentangle the effects of antiferromagnetic fluctuations and local electronic correlations in the formation of an insulating state. This allows us to identify the Slater and Heisenberg regimes in the phase diagram, which are separated by a crossover region of competing spatial and local electronic correlations. We identify the crossover regime by investigating the behavior of the local magnetic moment, shedding light on the formation of the insulating state at intermediate couplings.