Fractional quantum Hall states of dipolar gases in Chern bands
Fractional quantum Hall states of dipolar gases in Chern bands
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陈能带中偶极气体的分数量子霍尔态
DOI：
10.1103/physrevb.91.075102
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发表时间：
2014-10
影响因子：
3.7
通讯作者：
Yin, Lan
中科院分区：
文献类型：
--
作者：
Zeng, Tian-Sheng;Yin, Lan
我们研究了费米子和硬核玻色子在拓扑棋盘格中的分数填充下的长距离偶极相互作用，它们具有近距离跳跃到下一近邻\cite{Neupert2011}。我们考虑了在没有各向异性相互作用的情况下，偶极子在外场作用下沿垂直方向排列的情况。利用精确对角化，我们发现在中等偶极相互作用强度下，在最低的Chern带中，费米子（玻色子）在填充因子为1/3和1/5（填充因子为1/2和1/4）时分数量子霍尔（FQH）态的清晰特征。研究了这些FQH状态对长程相互作用尾部和频带平坦度的鲁棒性。当偶极相互作用减弱时，费米子的FQH态变为正常态，玻色子的1/4-FQH态变为超流体态。玻色子1/2-FQH态即使在没有偶极相互作用的情况下仍然存在，但当硬核变成具有临界现场排斥的软核时就消失了。在薄环面极限下，静态密度结构因子表明FQH状态转变为相称电荷密度波（CDW）状态。
We study fermions and hardcore bosons with long range dipolar interactions at fractional fillings in a topological checkerboard lattice with short-range hoppings up to next-next-nearest neighbors \cite{Neupert2011}. We consider the case that the dipoles are aligned in the perpendicular direction by an external field without the complication of anisotropic interaction. Using exact diagonalization, we find clear signatures of fractional quantum Hall (FQH) states at filling factors 1/3 and 1/5 for fermions (1/2 and 1/4 for bosons) in the lowest Chern band with a robust spectrum gap at moderate dipolar interaction strength. The robustness of these FQH states against long-range interaction tail and band flatness is investigated. When the dipolar interaction decreases, the fermionic FQH states turn into normal states, and the bosonic 1/4-FQH state turns into a superfluid state. The bosonic 1/2-FQH state survives even in the absence of the dipolar interaction, but vanishes when the hard core becomes a soft core with a critical onsite repulsion. In the thin torus limit, the static density structure factors indicates that the FQH state turns into a commensurate charge density wave (CDW) state.