Parent Phases of Doped Mott Insulators: A Cluster DMFT Study

TL;DR

This study uses Cluster DMFT to explore various symmetry-breaking insulating phases in a frustrated Hubbard model, revealing multiple competing states and fluctuation phenomena relevant to doped Mott insulators.

Contribution

It provides a detailed analysis of the symmetry-breaking phases and fluctuation dynamics in a frustrated Hubbard model using Cluster DMFT, highlighting new insights into Mott insulator behavior.

Findings

Identification of multiple mean-field solutions including Neel, dimer, and Mott phases.

Observation of softening singlet fluctuations and associated low-lying dimerization and chiral fluctuations.

Elucidation of the evolution of these phases with increasing frustration.

Abstract

We investigate the insulating phases of a frustrated Hubbard model in its strong coupling regime at half-filling. We pay special attention to all the symmetry breaking instabilities that can be described by Dynamical Mean Field Theory (DMFT) on a square plaquette. We identify several mean-field solutions, two Neel states breaking the SU(2) symmetry, a dimer phase and a Mott insulator which doesn't break any symmetry. The singlet to singlet fluctuations soften dramatically in the latter phase, giving rise to dimerization fluctuations as well as chiral fluctuations that are both low-lying. We present a simple picture of the different DMFT states and their evolution with frustration.