Schwinger-Boson Mean Field Solution of Spin-1 (or 1/2) 2D Anisotropic Heisenberg Antiferromagnet

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Using the Resonant Valence Bond (RVB) concept and the Schwinger-boson mean field approximation, we investigate a two dimensional anisotropic Heisenberg antiferromagnet. We find that increasing the coupling ratio (α=Jy/Jₓ), a disordered-ordered phase transition appears beyond a critical value (αc). When α>αc there exists a finite Tₙ beyond which an ordered-disordered phase transition occurs, while for α<αc there always exists a gap. Also we find that a decoupling temperature TD exists for 1D and 2D isotropic case, when T approaches TD the RVB order parameter decreases rapidly to zero.