Absence of the coexistence of superconductivity and antiferromagnetism in the hole-doped two-dimensional extended t-J model

The possibility of coexistence of superconductivity (SC) and antiferromagnetic long-range order (AFLRO) of the two-dimensional extended t-J model in the very underdoped region is studied by the variational Monte Carlo (VMC) method. In addition to using previously studied wave functions, a recently proposed wave function generated from the half-filled Mott insulator is used. For hole-doped systems, the phase boundary between AFLRO and d-wave SC for the physical parameters, J∕t=0.3, t^′∕t=−0.3 and t^″∕t=0.2, is located near hole density δ_c≅0.06, and there is no coexistence. The phase transition is first order between these two homogeneous phases at δ_c.