d-wave superconductivity and its coexistence with antiferromagnetism in t-J-U model: Statistically consistent Gutzwiller approach

TL;DR

This paper investigates the coexistence of antiferromagnetism and d-wave superconductivity in the t-J-U model using a statistically consistent Gutzwiller approach, revealing narrow coexistence regions near the Mott insulator state.

Contribution

It introduces a self-consistent Gutzwiller approximation for the t-J-U model, providing more accurate insights into AF and SC coexistence than standard mean field theories.

Findings

Coexistence occurs only for U/|t| > 10.6 near the Mott insulator.

The coexistence region is very narrow, with doping less than 0.006.

A small spin-triplet component appears in the superconducting gap in the coexistence phase.

Abstract

We discuss the coexistence of antiferromagnetism and d-wave superconductivity within the so-called statistically-consistent Gutzwiller approximation (SGA) applied to the t-J-U model. In this approach, the averages calculated in a self-consistent manner coincide with those determined variationally. Such consistency is not guaranteed within the standard renormalized mean field theory. With the help of SGA, we show that for the typical value J/|t| = 1/3, coexistence of antiferromagnetism (AF) and superconductivity (SC) appears only for U/|t| > 10.6 and in a very narrow range of doping (\delta < 0.006) in the vicinity of the Mott insulating state, in contrast to some previous reports. In the coexistent AF+SC phase, a staggered spin-triplet component of the superconducting gap appears also naturally; its value is very small.