arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1003.6070cond-mat.str-elcond-mat.quant-gascond-mat.stat-mech
收藏

领结晶格对偶上的硬核玻色子

Hardcore bosons on the dual of the bowtie lattice

Wanzhou Zhang, Laixi Li, Wenan Guo

摘要:

本文研究了硬核玻色子在蝴蝶结晶格对偶上的零温相图。讨论了两种类型的条纹对角长程序(条纹序I和条纹序II)。一个状态与II型条纹秩序和超流性被发现,即使没有最近邻排斥。这种状态的出现是由于晶格结构的不均匀性和各向异性。然而,既不破坏平移对称性,也不破坏原晶格的子晶格之间的对称性。在本文中,我们限制一个“固体状态”的格子玻色子作为一个对角长程有序状态打破平移对称的原始晶格或不同的子晶格的对称性。因此,我们将这种相称为条纹超流相(SSF)。在最近邻排斥作用下,当跳跃幅度小于排斥作用时,我们发现了两个条纹电荷密度波相(SCDW I和II),它们分别具有玻色子密度$ρ=1/2$(条纹阶I)和$ρ=2/3$(条纹阶II). SCDW I态是固体,其中原始晶格的平移对称性被破坏。我们观察到一个相当特殊的一阶相变,当跳跃项足够小时,在两个SCDW相之间显示出有趣的多回线滞后现象。这可以用经典极限附近的基态的特殊简并来解释。SSF重新出现在两个SCDW相位之外。SCDW I和SSF相之间的转变是一级的,而SCDW II和SSF相之间的转变是连续的。我们发现在有排斥和没有排斥的SSF态中,超流刚度是各向异性的。在具有斥力的SSF中,在接近半填充和超过2/3填充的区域,超流刚度表现出不同类型的各向异性。

英文摘要:

We study the zero temperature phase diagram of hardcore bosons on the dual of the bowtie lattice. Two types of striped diagonal long-range order (striped order I and striped order II) are discussed. A state with type-II striped order and superfluidity is found, even without nearest-neighbor repulsion. The emergence of such a state is due to the inhomogeneity and the anisotropy of the lattice structure. However, neither the translational symmetry nor the symmetry between sublattices of the original lattice is broken. In this paper, we restrict a 'solid state' of lattice bosons as a diagonal long-range ordered state breaking either the translational symmetry of the original lattice or the symmetry of different sublattices. We thus name such a phase a striped superfluid phase (SSF). In the presence of a nearest-neighbor repulsion, we find two striped charge density wave phases(SCDW I and II) with boson density $ρ=1/2$ (with striped order I) and $ρ=2/3$ (with striped order II) respectively, when the hopping amplitude is small compared with the repulsion. The SCDW I state is a solid, in which the translational symmetry of the original lattice is broken. We observe a rather special first-order phase transition showing an interesting multi-loop hysteresis phenomenon between the two SCDW phases when the hopping term is small enough. This can be accounted for by the special degeneracy of the ground states near the classical limit. The SSF re-appears outside the two SCDW phases. The transition between the SCDW I and SSF phases is first order, while the transition between SCDW II and SSF phases is continuous. We find that the superfluid stiffness is anisotropic in the SSF states with and without repulsion. In the SSF with repulsion, the superfluid stiffness is subject to different types of anisotropy in the region near half filling and above 2/3-filling.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑