Magnetic fragmentation and fractionalized Goldstone modes in a bilayer quantum spin liquid
Magnetic fragmentation and fractionalized Goldstone modes in a bilayer quantum spin liquid
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DOI：
10.1103/physrevresearch.5.l022062
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发表时间：
2023-02
影响因子：
4.2
通讯作者：
Aayush Vijayvargia;E. Nica;R. Moessner;Yuan-Ming Lu;O. Erten
中科院分区：
文献类型：
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作者：
Aayush Vijayvargia;E. Nica;R. Moessner;Yuan-Ming Lu;O. Erten
研究了正方晶格上具有Kitaev型相互作用的双层量子自旋液体模型的相图。我们证明了低能量极限是由一个$\pi$-通量Hubbard模型与增强SO（4）对称性。Hubbard模型的反铁磁Mott转变信号的自旋和轨道的自由度的双层的磁性碎片转变。分段的“N\'eel顺序“的特点是一个非本地字符串顺序参数的平面内N\' eel组件，除了一个各向异性的本地顺序参数。当N\'eel矢量沿着$\hat{z}$方向时，伴随的量子序是一个涌现的$\mathbb {Z}_{2} \times \mathbb{Z}_{2}$规范场，否则是一个涌现的$\mathbb{Z}_2$规范场.我们支持这些结果与微扰计算，这是一致的场论分析。最后，我们讨论了这些相的低能集体激发，并证明了$\mathbb{Z}_{2} \times \mathbb {Z}_{2}$相的Goldstone玻色子是分形的和非局域的.
We study the phase diagram of a bilayer quantum spin liquid model with Kitaev-type interactions on a square lattice. We show that the low energy limit is described by a $\pi$-flux Hubbard model with an enhanced SO(4) symmetry. The antiferromagnetic Mott transition of the Hubbard model signals a magnetic fragmentation transition for the spin and orbital degrees of freedom of the bilayer. The fragmented"N\'eel order"features a non-local string order parameter for an in-plane N\'eel component, in addition to an anisotropic local order parameter. The associated quantum order is characterized by an emergent $\mathbb{Z}_{2} \times \mathbb{Z}_{2}$ gauge field when the N\'eel vector is along the $\hat{z}$ direction, and a $\mathbb{Z}_2$ gauge field otherwise. We underpin these results with a perturbative calculation, which is consistent with the field theory analysis. We conclude with a discussion on the low energy collective excitations of these phases and show that the Goldstone boson of the $\mathbb{Z}_{2} \times \mathbb{Z}_{2}$ phase is fractionalized and non-local.