Mott correlated states in the underdoped two-dimensional Hubbard model: variational Monte Carlo versus a dynamical cluster approximation

TL;DR

This study compares variational Monte Carlo and dynamical cluster approximation methods to analyze Mott correlated states in the underdoped two-dimensional Hubbard model, revealing a crossover to non-Fermi liquid behavior and phase separation conditions.

Contribution

It provides a comparative analysis of two advanced computational approaches to understand correlated states in the Hubbard model, highlighting the conditions for phase separation.

Findings

Rapid crossover from weakly correlated metal to non-Fermi liquid state at small doping.

Phase separation occurs only at large U or high frustration, not in cuprate-relevant parameters.

No phase separation in the parameter range relevant for cuprates.

Abstract

We investigate the properties of the frustrated underdoped Hubbard model on the square lattice using two complementary approaches, the dynamical cluster extension of dynamical mean field theory, and variational Monte Carlo simulations of Gutzwiller-Jastrow wavefunctions with backflow corrections. We compare and discuss data for the energy and the double occupancies, as obtained from both approaches. At small dopings, we observe a rapid crossover from a weakly correlated metal at low interaction strength U to a non-Fermi liquid correlated state with strong local spin correlations. Furthermore, we investigate the stability of the correlated state against phase separation. We observe phase separation only for large values of U or very large frustration. No phase separation is present for the parameter range relevant for the cuprates.