Dynamically enhanced magnetic incommensurability: Effects of local dynamics on non-local spin-correlations in a strongly correlated metal

TL;DR

This paper investigates how local dynamical effects influence non-local spin correlations and magnetic ordering in a strongly correlated metal, revealing that vertex corrections can induce incommensurate magnetic orderings.

Contribution

It demonstrates that frequency-dependent vertex corrections from DMFT significantly alter the spin susceptibility and favor incommensurate magnetic orderings in the Hubbard model.

Findings

Vertex corrections promote incommensurate spin correlations.

Local dynamics influence non-local spin susceptibility.

Magnetic ordering wave vector relates to Fermi surface geometry.

Abstract

We compute the spin susceptibility of the two-dimensional Hubbard model away from half-filling, and analyze the impact of frequency dependent vertex corrections as obtained from the dynamical mean field theory (DMFT). We find that the local dynamics captured by the DMFT vertex strongly affects non-local spin correlations, and thus the momentum dependence of the spin susceptibility. While the widely used random phase approximation yields commensurate N\'eel-type antiferromagnetism as the dominant instability over a wide doping range, the vertex corrections favor incommensurate ordering wave vectors away from $(\pi,\pi)$. Our results indicate that the connection between the magnetic ordering wave vector and the Fermi surface geometry, familiar for weakly interacting systems, can hold in a strongly correlated metal, too.