Spin-Peierls Instability of Three-Dimensional Spin Liquids with Majorana Fermi Surfaces
Spin-Peierls Instability of Three-Dimensional Spin Liquids with Majorana Fermi Surfaces
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DOI：
10.1103/physrevlett.115.177205
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发表时间：
2015-10-22
影响因子：
8.6
通讯作者：
Rosch, Achim
中科院分区：
文献类型：
--
作者：
Hermanns, Maria;Trebst, Simon;Rosch, Achim
Kitaev 模型的三维 (3D) 变体可以在某些三配位晶格结构（例如最近引入的超八边形晶格）上容纳具有马约拉纳费米表面的无间隙自旋液体。在这里，我们研究了由额外的自旋交换项（例如海森堡耦合）引起的费米表面不稳定性，这些项引入了新出现的马约拉纳费米子自由度之间的相互作用。我们表明，与相互作用的符号和结构无关，马约拉纳表面总是不稳定的。一般来说，系统在指数级小的温度下自发地加倍其晶胞，并形成具有线节点的自旋液体。根据显微镜的不同，系统的进一步对称性可能会在此转变时被打破。 3D 自旋液体的这些自旋-佩尔尔斯不稳定性与费米子的 BCS 不稳定性密切相关。
Three-dimensional (3D) variants of the Kitaev model can harbor gapless spin liquids with a Majorana Fermi surface on certain tricoordinated lattice structures such as the recently introduced hyperoctagon lattice. Here, we investigate Fermi surface instabilities arising from additional spin exchange terms (such as a Heisenberg coupling) which introduce interactions between the emergent Majorana fermion degrees of freedom. We show that independent of the sign and structure of the interactions, the Majorana surface is always unstable. Generically, the system spontaneously doubles its unit cell at exponentially small temperatures and forms a spin liquid with line nodes. Depending on the microscopics, further symmetries of the system can be broken at this transition. These spin-Peierls instabilities of a 3D spin liquid are closely related to BCS instabilities of fermions.