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 …