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arXiv 0903.1630cond-mat.str-elcond-mat.stat-mech
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具有四自旋相互作用的海森堡反铁磁体的Phase diagram

Phase diagram of the Heisenberg antiferromagnet with four-spin interactions

L. Isaev, G. Ortiz, J. Dukelsky

摘要:

利用最近提出的分层平均场方法,研究了具有四自旋环交换相互作用的海森堡平面反铁磁体的量子相图。通过确定相关的自由度,我们能够使用一个单一的变分anzatz映射模型的整个相图,并揭示其各个阶段的性质。结果表明,在Néel态和量子顺磁相之间存在一个跃迁,其特征是平移不变性被破坏.非磁性相保持晶格旋转对称性,并具有相关元格性质。我们的研究结果还表明,这种相变可以适当地描述在朗道范式。

英文摘要:

We study the quantum phase diagram of the Heisenberg planar antiferromagnet with a subset of four-spin ring exchange interactions, using the recently proposed heirarchical mean-field approach. By identifying relevant degrees of freedom, we are able to use a single variational anzatz to map the entire phase diagram of the model and uncover the nature of its various phases. It is shown that there exists a transition between a Néel state and a quantum paramagnetic phase, characterized by broken translational invariance. The non-magnetic phase preserves the lattice rotational symmetry, and has a correlated plaquette nature. Our results also suggest that this phase transition can be properly described within the Landau paradigm.

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