One-dimensional extended Hubbard model with soft-core potential

TL;DR

This paper explores the phase diagram of a one-dimensional extended Hubbard model with soft-core interactions, revealing cluster Luttinger liquids, a supersymmetric critical line, and minimal spin correlations using DMRG simulations.

Contribution

It introduces the existence of cluster Luttinger liquid phases and a supersymmetric critical point in a soft-core Hubbard model, expanding understanding of 1D quantum phases.

Findings

Identification of cluster Luttinger liquid phases

Discovery of a supersymmetric critical line with central charge 5/2

Minimal spin correlations in the studied phases

Abstract

We investigate the $T=0$ phase diagram of a variant of the one-dimensional extended Hubbard model where particles interact via a finite-range soft-shoulder potential. Using Density Matrix Renormalization Group (DMRG) simulations, we evidence the appearance of Cluster Luttinger Liquid (CLL) phases, similarly to what first predicted in a hard-core bosonic chain [M. Mattioli, M. Dalmonte, W. Lechner, and G. Pupillo, Phys. Rev. Lett. 111, 165302]. As the interaction strength parameters change, we find different types of clusters, that encode the order of the ground state in a semi-classical approximation and give rise to different types of CLLs. Interestingly, we find that the conventional Tomonaga Luttinger Liquid (TLL) is separated by a critical line with a central charge $c=5/2$, along which the two (spin and charge) bosonic degrees of freedom (corresponding to $c=1$ each) combine in a supersymmetric way with an emergent fermionic excitation ($c=1/2$). We also demonstrate that there are no significant spin correlations.