Luttinger liquid behaviour and superconducting correlations in t-J ladders

TL;DR

This paper investigates the low-energy properties of the isotropic t-J ladder system using exact diagonalization, revealing phases with Luttinger liquid behavior and dominant superconducting correlations at higher densities.

Contribution

It provides a detailed phase diagram and identifies the conditions under which superconducting correlations dominate in the t-J ladder system.

Findings

Identification of a Tomonaga-Luttinger-like phase at low electron density.

Discovery of a gapped phase with power-law pairing correlations at higher densities.

Large region with dominant superconducting correlations.

Abstract

The low energy behaviour of the isotropic t--J ladder system is investigated using exact diagonalization techniques, specifically finding the Drude weight, the charge velocity and the compressibility. By applying the ideas of Luttinger liquid theory, we determine the correlation exponent $K_\rho$ which defines the behaviour of the long range correlations in the system. The boundary to phase separation is determined and a phase diagram is presented. At low electron density, a Tomonaga-Luttinger-like phase is stabilized whilst at higher electron densities a gapped phase with power law pairing correlations is stabilized: A large region of this gapped phase is found to exhibit dominant superconducting correlations.