Renormalization group analysis of dipolar Heisenberg model on square lattice
Renormalization group analysis of dipolar Heisenberg model on square lattice
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DOI：
10.1103/physrevb.97.245105
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发表时间：
2018-03
影响因子：
3.7
通讯作者：
A. Keles;E. Zhao
中科院分区：
文献类型：
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作者：
A. Keles;E. Zhao
我们给出了正方形晶格上自旋1/2偶极海森堡模型的泛函重整化群分析。该模型类似于著名的J_1~J_2模型，描述了具有长程各向异性偶极-偶极相互作用的深光晶格中极性分子的赝旋自由度。先前基于张量网络ANSATZ的模型研究表明，对于某些偶极倾角，存在顺磁基态，可以在实验中调节该基态来控制交换耦合。在小的团簇晶胞上形成的张量ansatz不足以描述螺旋有序性，因此在大方位倾角下的相图仍然是未知的。在这里，我们通过数值赝费米子泛函重整化群计算得到了模型的完整相图。结果表明，在N{e}EL和条状/螺旋相之间实现了一个扩展的量子顺磁相。在这个区域，自旋磁化率平稳地向下流动到最低的数值重整化群尺度，没有发散或破裂的迹象，这与流向长程有序相的流动形成鲜明对比。我们的结果进一步证明偶极海森堡模型是量子自旋液体的沃土。
We present a detailed functional renormalization group analysis of spin-1/2 dipolar Heisenberg model on square lattice. This model is similar to the well known $J_1$-$J_2$ model and describes the pseudospin degrees of freedom of polar molecules confined in deep optical lattice with long-range anisotropic dipole-dipole interactions. Previous study of this model based on tensor network ansatz indicates a paramagnetic ground state for certain dipole tilting angles which can be tuned in experiments to control the exchange couplings. The tensor ansatz formulated on a small cluster unit cell is inadequate to describe the spiral order, and therefore the phase diagram at high azimuthal tilting angles remains undetermined. Here we obtain the full phase diagram of the model from numerical pseudofermion functional renormalization group calculations. We show that an extended quantum paramagnetic phase is realized between the N\'{e}el and stripe/spiral phase. In this region, the spin susceptibility flows smoothly down to the lowest numerical renormalization group scales with no sign of divergence or breakdown of the flow, in sharp contrast to the flow towards the long-range ordered phases. Our results provide further evidence that the dipolar Heisenberg model is a fertile ground for quantum spin liquids.