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arXiv · 1305.6305

Phase transitions in the two-dimensional Anisotropic Biquadratic Heisenberg Model

Antônio R. Moura·Antônio S. T. Pires·Afrânio R. Pereira
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Abstract

In this paper we study the influence of the single-ion anisotropy in the two-dimensional biquadratic Heisenberg model (ABHM) on the square lattice at zero and finite low temperatures. It is common to represent the bilinear and biquadratic terms by $J_1=J\cosθ$ and $J_2=J\sinθ$, respectively, and it is well documented the many phases present in the model as function of $θ$. However we have adopted a constant value for the bilinear constant ($J_1=1$) and small values of the biquadratic term ($|J_2| D_c$, the excited states are gapped and there is no spin long-range order (LRO) even at zero temperature. Using Schwinger bosonic representation and Self-Consistent Harmonic Approximation (SCHA), we have studied the quantum and thermal phase transitions as a function of the bilinear and biquadratic constants.

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Antônio R. Moura, Antônio S. T. Pires, Afrânio R. Pereira. 2013-11-19. Phase transitions in the two-dimensional Anisotropic Biquadratic Heisenberg Model. https://doi.org/10.1016/j.jmmm.2014.01.006

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