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arXiv 1905.03065cond-mat.str-el
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扩展哈伯德模型中反铁磁与电荷密度波涨落的竞争

Competition between antiferromagnetic and charge density wave fluctuations in the extended Hubbard model

Petra Pudleiner, Anna Kauch, Karsten Held, Gang Li

摘要:

通过扩展我们的{ \it victory}实现的拼花方法,包括非本地库仑相互作用,我们研究了扩展的哈伯德模型的二维正方形晶格上的非本地电荷和自旋波动的竞争特别关注。令人惊讶的是,我们发现,它们的竞争,作为驱动的机制,相变对电荷密度波,占主导地位的相变附近的一个非常窄的参数制度。由于特殊的几何形状和费米表面拓扑的正方形晶格,反铁磁波动占主导地位,即使是相当大的次近邻相互作用。我们的结论是基于单粒子和双粒子物理量的一致观测,包括自能、单粒子谱函数、双粒子磁化率、密度-密度顶点函数和光学电导率。我们的工作无偏地建立了这些量与电荷涨落的联系,并且解释的方式可以很容易地应用于任何访问两粒子顶点的多体方法。

英文摘要:

By extending our {\it victory} implementation of the parquet approach to include non-local Coulomb interactions, we study the extended Hubbard model on the two-dimensional square lattice with a particular focus on the competition of the non-local charge and spin fluctuations. Surprisingly, we find that their competition, as the mechanism driving the phase transition towards the charge density wave, dominates only in a very narrow parameter regime in the immediate vicinity of the phase transition. Due to the special geometry and the Fermi surface topology of the square lattice, antiferromagnetic fluctuations dominate even for sizable next-nearest neighbor interactions. Our conclusions are based on the consistent observations in both the single- and two- particle quantities, including the self-energy, the single-particle spectral function, the two-particle susceptibility, the density-density vertex function and the optical conductivity. Our work unbiasedly establishes the connection of these quantities to the charge fluctuations, and the way of interpretation can be readily applied to any many-body method with access to the two-particle vertex.

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