The quantum<i>J</i>₁–<i>J</i>₁′–<i>J</i>₂spin-1/2 Heisenberg model: influence of the interchain coupling on the ground-state magnetic ordering in two dimensions

Abstract

We study the phase diagram of the two-dimensional (2D) J 1 -J 1 -J 2 spin-1/2 Heisenberg model by means of the coupled cluster method. The effect of the coupling J 1 on the Nel and stripe states is investigated. We find that the quantum critical points for the Nel and stripe phases increase as the coupling strength J 1 is increased, and an intermediate phase emerges above the region at J 1 0.6 when J 1 = 1. We find indications for a quantum triple point at J 1 0.60 0.03, J 2 0.33 0.02 for J 1 = 1.