Development of superconducting correlation at low temperatures in the two-dimensional t-J model

TL;DR

This study investigates the development of superconducting correlations in the two-dimensional t-J model at low temperatures, revealing a rapid growth of d-wave pairing correlations indicative of superconductivity.

Contribution

It provides the first detailed analysis of pairing correlations in the t-J model at low temperatures using high-temperature expansion methods, highlighting the emergence of d-wave superconductivity.

Findings

d-wave correlations grow rapidly at low temperatures for certain electron densities

Effective attractive interaction between quasi-particles in d-wave pairing

Contrasts with Hubbard model where no superconductivity is observed

Abstract

The equal-time pairing correlation function of the two-dimensional t-J model on a square lattice is studied using a high-temperature expansion method. The sum of the pairing correlation, its spatial dependence, and the correlation length are obtained as functions of temperature down to $T \simeq 0.2 t$. By comparison of single-particle contributions in the correlation functions, we find an effective attractive interaction between quasi-particles in $d_{x^2-y^2}$-wave pairings. It is shown that d-wave correlation grows rapidly at low temperatures for 0.5 < n < 0.9, with n being the electron density. The temperature for this growth is roughly scaled by J/2. This is in sharp contrast to the Hubbard model in a weak or intermediate coupling region, where there is no numerical evidence of superconductivity.