Competing quantum spin liquids, gauge fluctuations, and anisotropic interactions in a breathing pyrochlore lattice
Competing quantum spin liquids, gauge fluctuations, and anisotropic interactions in a breathing pyrochlore lattice
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DOI：
10.1103/physrevb.106.134402
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发表时间：
2022-07
影响因子：
3.7
通讯作者：
Li Ern Chern;Yong Baek Kim;C. Castelnovo
中科院分区：
文献类型：
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作者：
Li Ern Chern;Yong Baek Kim;C. Castelnovo
利用投影对称群分析方法对具有呼吸各向异性的φ= 1 / 2烧绿石磁体上的量子自旋液体进行了分类。我们发现了40种Z2自旋液体和16种<$（1）自旋液体，它们遵循<$$> 43<$空间群和时间反演对称性。作为应用，我们考虑了反铁磁海森堡模型，它被认为是候选材料Ba 3 Yb 2 Zn 5 O 11中的主导相互作用。聚焦于π（1）自旋液体ansatze，我们发现，当限制在这个模型中时，只有两个是物理的。我们为这两种（1）自旋液体中的每一种提供了部分子平均场理论的解析解。结果表明，其中一个是无隙的，而另一个是有隙的，自旋激发。无论呼吸各向异性的程度如何，这两种π（1）自旋液体的能量都是相等的，并且它们可以通过来自二次分散的无带隙自旋子的低温热容贡献来区分。我们进一步证明，在无规相位近似下，后者不受π（1）规范场涨落的影响。最后，我们证明了一个小的Dzyaloshinskiii-Moriya相互作用提升了两个π（1）自旋液体之间的简并度，并最终导致晶格在强耦合下解耦成独立的四面体。虽然目前的模型参数为Ba 3 Yb 2 Zn 5 O 11的地方，它确实在去耦制度，其他候选材料可能会在不久的将来合成，实现我们的工作中讨论的自旋液体状态。
We use the projective symmetry group analysis to classify the quantum spin liquids on the 𝑆 = 1 / 2 pyrochlore magnet with a breathing anisotropy. We find 40 Z 2 spin liquids and 16 𝑈 ( 1 ) spin liquids that respect the 𝐹 ¯43 𝑚 space group and the time reversal symmetry. As an application, we consider the antiferromagnetic Heisenberg model, which is proposed to be the dominant interaction in the candidate material Ba 3 Yb 2 Zn 5 O 11 . Focusing on the 𝑈 ( 1 ) spin liquid ansatze, we find that only two of them are physical when restricted to this model. We present an analytical solution to the parton mean field theory for each of these two 𝑈 ( 1 ) spin liquids. It is revealed that one of them has gapless, while the other one has gapped, spinon excitations. The two 𝑈 ( 1 ) spin liquids are equal in energy regardless of the degree of breathing anisotropy, and they can be differentiated by the low-temperature heat capacity contribution from the quadratically-dispersing gapless spinons. We further show that the latter is unaffected by fluctuations of the 𝑈 ( 1 ) gauge field within the random phase approximation. Finally, we demonstrate that a small Dzyaloshinskii-Moriya interaction lifts the degeneracy between the two 𝑈 ( 1 ) spin liquids, and it eventually causes the lattice to decouple into independent tetrahedra at strong coupling. While current model parameters for Ba 3 Yb 2 Zn 5 O 11 place it indeed in the decoupled regime, other candidate materials may be synthesised in the near future that realize the spin liquid states discussed in our work.