扩展Bose-哈伯德模型中的阻挫诱导无公度固体
Frustration induced incommensurate solids in the extended Bose-Hubbard model
摘要：
利用量子Monte Carlo方法研究了正方晶格上具有最近邻和次最近邻$(V, V')$排斥相互作用的扩展Bose-哈伯德模型.不同于强$V'$的情况下，基态可以是条纹固体或条纹超固体，我们专注于弱$V' < V/2$和小跳跃，并发现，在热力学极限，从1/4到1/2的分数密度不等的无公度固体可以稳定。我们还表明，无公度固体，其特征在于从$(π,π/2)$（或$(π/2,π)$）到$(π,π)$的一组连续的波矢量变化，可以理解的畴壁形成的机制。讨论了相关的基态相图和热相变。
英文摘要：
We study the extended Bose-Hubbard model with nearest-neighbor and next-nearest-neighbor $(V, V')$ repulsive interactions on a square lattice by using the quantum Monte Carlo method. Unlike the case of strong $V'$ where the ground states can be striped solids or striped supersolids, we focus on weak $V' < V/2$ and small hoppings and find that, in the thermodynamic limit, incommensurate solids of fractional densities varying from 1/4 to 1/2 can be stabilized. We also show that the incommensurate solids, which are characterized by a continuous set of wave vectors changing from $(π,π/2)$ (or $(π/2,π)$) to $(π,π)$, can be understood by a mechanism of domain wall formation. The related ground-state phase diagram and thermal phase transitions are also discussed.
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