Finite-Temperature Mott Transition in Two-Dimensional Frustrated Hubbard Models

TL;DR

This study explores how geometrical frustration in two-dimensional Hubbard models affects the Mott transition, revealing stabilization of metallic phases, heavy fermion behavior, and reentrant transition phenomena relevant to organic materials.

Contribution

It demonstrates the role of geometrical frustration in stabilizing metallic phases and inducing reentrant Mott transitions in two-dimensional Hubbard models.

Findings

Metallic phase persists at large interactions due to frustration.

Reentrant Mott transition observed in anisotropic triangular lattice.

Reentrant behavior aligns with experimental observations in organic materials.

Abstract

We investigate the Hubbard model on two typical frustrated lattices in two dimensions, the kagome lattice and the anisotropic triangular lattice, by means of the cellular dynamical mean field theory. We show that the metallic phase is stabilized up to fairly large Hubbard interactions under strong geometrical frustration in both cases, which results in heavy fermion behavior and several anomalous properties around the Mott transition point. In particular, for the anisotropic triangular lattice, we find novel reentrant behavior in the Mott transition in the moderately frustrated parameter regime, which is caused by the competition between Fermi-liquid formation and magnetic correlations. It is demonstrated that the reentrant behavior is a generic feature inherent in the Mott transition with intermediate geometrical frustration, and indeed in accordance with recent experimental findings for organic materials.