湮灭狄拉克费米子的拓扑阻塞原子极限
Topological obstructed atomic limit by annihilating Dirac fermions
摘要：
我们发现，湮灭一对狄拉克费米子意味着从临界半金属相的拓扑过渡到阻碍原子极限（OAL）绝缘体相，而不是平凡的绝缘体。这是因为发生分支切割的相位的波函数，导致非平凡的Zak相位沿某些方向。为此，我们研究了它们的Z $_2$不变量，并利用纠缠熵研究了相变。我们用低能哈密顿量和模型系统的数值结果来说明这种效应。在包括应变石墨烯和弯曲的蜂窝V族（Sb/As）的现实材料中观察到这些转变。
英文摘要：
We show that annihilating a pair of Dirac fermions implies a topological transition from the critical semi-metallic phase to an Obstructed Atomic Limit (OAL) insulator phase instead of a trivial insulator. This is shown to happen because of branch-cuts in the phase of the wave functions, leading to non trivial Zak phase along certain directions. To this end, we study their Z$_2$ invariant and also study the phase transition using Entanglement Entropy. We use low energy Hamiltonians and numerical result from model systems to show this effect. These transitions are observed in realistic materials including strained graphene and buckled honeycomb group-V (Sb/As).
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