"Superconductor"-insulator transitions in a Hubbard chain with nearest- neighbor and bond-charge interactions

TL;DR

This paper investigates phase transitions in a half-filled Hubbard chain with various interactions, revealing insulating and superconducting phases and mapping their boundaries using topological order parameters.

Contribution

It introduces a phase diagram for a generalized Hubbard chain with correlated hopping, identifying a superconducting phase and employing Berry phases as order parameters.

Findings

Identifies charge- and spin-density wave insulating phases.

Discovers a superconducting phase at small U and V.

Constructs a phase diagram using topological Berry phases.

Abstract

We consider a half-filled generalized Hubbard chain with electron-hole symmetric correlated hopping and on-site and nearest-neighbor repulsions U and V respectively. In addition to the insulating charge- and spin-density wave phases for large V and U respectively, we identify a phase with dominant superconducting correlations at large distances for small U and V. Using two Berry phases (one associated to the charge and the other to the spin degrees of freedom) as discrete order parameters, we construct a phase diagram for the three thermodynamic phases.