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arXiv 0712.4338cond-mat.str-el
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哈伯德模型中的涨落电荷密度波

Fluctuating charge density waves in the Hubbard model

A. Sherman, M. Schreiber

摘要:

本文用强关联情形下的图解法研究了二维排斥哈伯德模型的电荷磁化率。在这种技术中,使用跳频常数的幂级数。结果表明,一旦费米能级穿过其中一个哈伯德子带,静态磁化率的动量依赖性就会出现一个尖锐的峰值。随着进一步偏离半填充,峰转变为围绕$Γ$点的脊。在所考虑的范围$0\leq|1-\bar{n}|\alt 0.2$的电子填充$\bar{n}$的静态磁化率是有限的,这指向的情况下的长程电荷有序。然而,对于$|1-\bar{n}|\approx 0.12$,磁化率最大值位于布里渊区的中心和边界之间的中间。在这种情况下,载流子与四方畸变的相互作用可以稳定具有四个晶格间距的波长的电荷密度波,如在铜酸镧的低温四方相中实验观察到的。在铜氧化物钙钛矿中固有的参数范围内,具有$\bar{n}$的磁化率演化的特征仅微弱地依赖于最近邻跳跃常数与Hubbard排斥的比率以及初始能带结构的细节。布里渊区极化率最大值的位置主要由$\bar{n}$的值决定。

英文摘要:

The charge susceptibility of the two-dimensional repulsive Hubbard model is investigated using the diagram technique developed for the case of strong correlations. In this technique, a power series in the hopping constant is used. It is shown that once the Fermi level crosses one of the Hubbard subbands a sharp peak appears in the momentum dependence of the static susceptibility. With further departure from half-filling the peak transforms to a ridge around the $Γ$ point. In the considered range $0\leq|1-\bar{n}|\alt 0.2$ of the electron filling $\bar{n}$ the static susceptibility is finite which points to the absence of the long-range charge ordering. However, for $|1-\bar{n}|\approx 0.12$ the susceptibility maxima are located halfway between the center and the boundaries of the Brillouin zone. In this case an interaction of carriers with tetragonal distortions can stabilize the charge density wave with the wavelength of four lattice spacings, as observed experimentally in the low-temperature tetragonal phase of lanthanum cuprates. In the range of parameters inherent in cuprate perovskites the character of the susceptibility evolution with $\bar{n}$ depends only weakly on the ratio of the nearest-neighbor hopping constant to the Hubbard repulsion and on details of the initial band structure. The location of the susceptibility maxima in the Brillouin zone is mainly determined by the value of $\bar{n}$.

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。

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