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arXiv 1501.02455cond-mat.quant-gascond-mat.str-el
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磁序驱动的Half-哈伯德模型的拓扑跃迁

Magnetic Order Driven Topological Transition in the Haldane-Hubbard Model

Wei Zheng, Huitao Shen, Zhong Wang, Hui Zhai

摘要:

在这封信中,我们研究了具有半填充的在位排斥相互作用的Halflit模型。我们发现,磁序的平均场哈密顿量,有效地修改参数的Halfen-Hamiltonian,如亚晶格的能量差和相位在下一个最近的跳跃。随着相互作用的增加,磁序的增加对应于改变这些参数,从而驱动拓扑转变。在平均场水平,一种情况是磁序不断增加,不可避免地,费米子间隙关闭在拓扑转变点与非零磁序。在平均场之外,由自旋波涨落介导的费米子之间的相互作用可以进一步打开能隙,呈现一阶跃迁。另一种情况是在平均场水平上的一阶跃迁,在此过程中,倾斜的磁序不连续地发展,避免了费米子能隙的闭合。我们发现这两种情况都存在于Haldaugh-哈伯德模型的相图中。我们的预言与最近在冷原子系统中实现的Halfton模型有关。

英文摘要:

In this letter we study the Haldane model with on-site repulsive interactions at half-filling. We show that the mean-field Hamiltonian with magnetic order effectively modifies parameters in the Haldane Hamiltonian, such as sublattice energy difference and phase in next nearest hopping. As interaction increases, increasing of magnetic order corresponds to varying these parameters and consequently, drives topological transitions. At the mean-field level, one scenario is that the magnetic order continuously increases, and inevitably, the fermion gap closes at the topological transition point with nonzero magnetic order. Beyond the mean-field, interaction between fermions mediated by spin-wave fluctuations can further open up the gap, rendering a first-order transition. Another scenario is a first-order transition at mean-field level across which a canted magnetic order develops discontinuously, avoiding the fermion gap closing. We find that both scenarios exist in the phase diagram of the Haldane-Hubbard model. Our predication is relevant to recent experimental realization of the Haldane model in cold atom system.

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