Doping dependence of antiferromagnetism inLa2CuO4: A numerical study based on a resonating-valence-bond state

Abstract

A paramagnetic resonating-valence-bond state is modified to become a long-range-ordered antiferromagnetic state by including a staggered magnetic field as a variational parameter. At half-filling this field is shown by using variational Monte Carlo method to lower the ground-state energy of the large-$U$ Hubbard model by 4%. A staggered moment of 0.37(1) is obtained. The antiferromagnetism is destroyed by doping with ∼5%-7% of holes for $\frac{t}{J}=\simeq 2.5-5$ and the paramagnetic state becomes stable. This result is shown to be in good agreement with experiments on ${\mathrm{La}}_2$Cu${\mathrm{O}}_4$-based compounds.