Role of backflow correlations for the non-magnetic phase of the t-t' Hubbard model

TL;DR

This paper enhances the accuracy of wave function approximations for the 2D Hubbard model by incorporating backflow correlations, revealing a stable non-magnetic insulating phase at strong coupling and high frustration.

Contribution

It introduces a novel method using backflow correlations to improve ground state approximations in the Hubbard model, especially for frustrated systems.

Findings

Backflow correlations stabilize a non-magnetic insulating phase.

The method improves accuracy of phase diagram predictions.

Non-magnetic phase appears at strong coupling and high frustration.

Abstract

We introduce an efficient way to improve the accuracy of projected wave functions, widely used to study the two-dimensional Hubbard model. Taking the clue from the backflow contribution, whose relevance has been emphasized for various interacting systems on the continuum, we consider many-body correlations to construct a suitable approximation for the ground state at intermediate and strong couplings. In particular, we study the phase diagram of the frustrated $t{-}t^\prime$ Hubbard model on the square lattice and show that, thanks to backflow correlations, an insulating and non-magnetic phase can be stabilized at strong coupling and sufficiently large frustrating ratio $t^\prime/t$.