Interlayer coupling effect on a bilayer Kitaev model
Interlayer coupling effect on a bilayer Kitaev model
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DOI：
10.1103/physrevb.97.094403
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发表时间：
2017-12
影响因子：
3.7
通讯作者：
Hiroyuki Tomishige;J. Nasu;A. Koga
中科院分区：
文献类型：
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作者：
Hiroyuki Tomishige;J. Nasu;A. Koga
我们研究了一个双层Kitaev模型，其中两个蜂窝层通过海森堡相互作用耦合，讨论了层间耦合对Kitaev量子自旋液体（QSL）的影响。在这个模型中，存在一个局域守恒量，导致系统中没有长程自旋关联。利用精确对角化、键算符平均场理论和团簇展开技术，我们研究了系统的基态性质。结果表明Kitaev QSL和单重态-二聚态之间存在一级量子相变。我们发现，由于局域守恒量的存在，单重态-二聚体基态的单重态激发是局域的。为了研究有限温度性质，我们利用热纯量子态方法。我们澄清，双峰结构的比热固有的Kitaev QSL保持甚至以上的量子相变。这些结果表明，Kitaev QSL对层间干扰是稳定的。多层Kitaev模型的磁性也解决了。
We investigate a bilayer Kitaev model, where two honeycomb layers are coupled by the Heisenberg interactions, to discuss effects of an interlayer coupling against the Kitaev quantum spin liquids (QSLs). In this model, there exists a local conserved quantity, which results in no long-range spin correlations in the system. Using the exact diagonalization, bond operator mean-field theory, and cluster expansion techniques, we study ground state properties in the system. The obtained results suggest the existence of a first-order quantum phase transition between the Kitaev QSL and singlet-dimer states. We find that one-triplet excitation from the singlet-dimer ground state is localized owing to the existence of the local conserved quantity. To examine finite-temperature properties, we make use of the thermal pure quantum state approach. We clarify that double-peak structure in the specific heat inherent in the Kitaev QSL is maintained even above the quantum phase transition. The present results suggest that the Kitaev QSL is stable against the interlayer interference. Magnetic properties of multilayer Kitaev models are also addressed.