Ground state phase diagram of the one-dimensional $t$-$J$ model with pair hopping terms

TL;DR

This study uses density matrix renormalisation group methods to explore how pair-hopping terms influence the ground state phase diagram of the one-dimensional $t$-$J$ model, revealing significant changes in superconducting regions.

Contribution

It introduces the inclusion of pair-hopping terms into the 1D $t$-$J$ model and analyzes their impact on the phase diagram using DMRG, which was previously neglected.

Findings

Pair-hopping terms extend the superconducting phase at low fillings.

Superconductivity is suppressed at larger fillings with pair-hopping.

The phase diagram is radically altered by the additional terms.

Abstract

The $t$-$J$ model is a standard model of strongly correlated electrons, often studied in the context of high-$T_c$ superconductivity. However, most studies of this model neglect three-site terms, which appear at the same order as the superexchange $J$. As these terms correspond to pair-hopping, they are expected to play an important role in the physics of superconductivity when doped sufficiently far from half-filling. In this paper we present a density matrix renormalisation group study of the one-dimensional $t$-$J$ model with the pair hopping terms included. We demonstrate that that these additional terms radically change the one-dimensional ground state phase diagram, extending the superconducting region at low fillings, while at larger fillings, superconductivity is completely suppressed. We explain this effect by introducing a simplified effective model of repulsive hardcore bosons.