arXiv:1305.2727 · Physical Review B
d -wave superconductivity and its coexistence with antiferromagnetism in the t – J – U model: Statistically consistent Gutzwiller approach
Marcin Abram, Jan Kaczmarczyk, Jakub Jȩdrak, Józef Spałek
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 $J/|t|=\frac{1}{3}$, coexistence of antiferromagnetism (AF) and superconductivity (SC) appears only for $U/|t|>10.6$ and in a very narrow range of doping $(\ensuremath{\delta}\ensuremath{\lesssim}0.006)$ 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.