Gossamer superconductivity and antiferromagnetism in the t‐J‐U model

Abstract

The d-wave superconductivity (dSC) and antiferromagnetism are analytically studied in a renormalized mean-field theory for a two-dimensional t‐J model plus an on-site repulsive Hubbard interaction U. The purpose of introducing the U term is to partially impose the no-double-occupancy constraint by employing the Gutzwiller approximation. The phase diagrams as functions of doping δ and U are studied. Using the standard value of t∕J=3.0 and in the large-U limit, we show that the antiferromagnetic (AF) order emerges and coexists with the dSC in the underdoped region below the doping δ∼0.1. The dSC order parameter increases from zero as the doping increases and reaches a maximum near the optimal doping δ∼0.15. In the small-U limit, only the dSC order survives while the AF order disappears. As U increases up to a critical value, the AF order shows up and coexists with the dSC in the underdoped regime. At half-filling, the system is in the dSC state for small U and becomes an AF insulator for large U. Within the present mean-field approach, we show that the ground-state energy of the coexistent state is always lower than that of the pure dSC state.

Source-reported materials — not catalogue approval

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