模型 Chern 绝缘体中的 Dirac 点合并与游走
Dirac points merging and wandering in a model Chern insulator
AI总结：
本文提出含复数近邻跃迁与子晶格势的正方晶格 Chern 绝缘体模型，揭示可移动、合并和分裂的 Dirac 点及特殊拓扑相变线，并指出其可在光学晶格中实验模拟。
摘要：
我们提出了一个正方晶格上的 Chern 绝缘体模型，该模型包含复数的第一和第二近邻跃迁以及一个子晶格势，并展现出出乎意料的丰富物理。与著名的 Haldane 模型类似，所提出的 Chern 绝缘体具有两个 Chern 数为 ±1 的拓扑非平凡相。作为本模型的显著特征，相变与可在动量空间中移动、合并和分裂的 Dirac 点相关，这与 Haldane 的 Chern 绝缘体形成对比，后者的 Dirac 点被束缚在六边形 Brillouin 区的角上。此外，所得相图揭示了两个不同拓扑相之间一条特殊的相变线，而 Haldane 模型中这种相变被缩减为子晶格势为零的一个点。该模型适合在光学晶格中进行模拟，从而促进对两个不同拓扑相之间相变的研究，以及对 Dirac 点合并和游走的实验分析。
英文摘要：
We present a model for a Chern insulator on the square lattice with complex first and second neighbor hoppings and a sublattice potential which displays an unexpectedly rich physics. Similarly to the celebrated Haldane model, the proposed Chern insulator has two topologically non-trivial phases with Chern numbers $\pm1$. As a distinctive feature of the present model, phase transitions are associated to Dirac points that can move, merge and split in momentum space, at odds with Haldane's Chern insulator where Dirac points are bound to the corners of the hexagonal Brillouin zone. Additionally, the obtained phase diagram reveals a peculiar phase transition line between two distinct topological phases, in contrast to the Haldane model where such transition is reduced to a point with zero sublattice potential. The model is amenable to be simulated in optical lattices, facilitating the study of phase transitions between two distinct topological phases and the experimental analysis of Dirac points merging and wandering.
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