Abstract

We study the properties of two electrons with Coulomb interactions in a tight-binding model of La-based cuprate superconductors. This tight-binding model is characterized by long-ranged hopping obtained previously by advanced quantum chemistry computations. We show analytically and numerically that the Coulomb repulsion leads to a formation of compact pairs propagating through the whole system. The mechanism of pair formation is related to the emergence of an effective narrow energy band for Coulomb electron pairs with conserved total pair energy and momentum. The dependence of the pair formation probability on an effective filling factor is obtained with a maximum around a filling factor of 20 (or 80) percent. The comparison with the case of the nearest neighbor tight-binding model shows that the long-ranged hopping provides an increase of the phase space volume with high pair formation probability. We conjecture that the Coulomb electron pairs discussed here may play a role in high temperature superconductivity.

Graphic abstract

中文翻译：

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La基铜酸盐超导体紧密结合模型中的库仑电子配对

摘要

我们研究了基于La的铜酸盐超导体的紧密结合模型中具有库仑相互作用的两个电子的性质。这种紧密结合的模型的特征是以前通过高级量子化学计算获得的远距离跳跃。我们通过分析和数值分析表明，库仑排斥力导致形成紧凑对，并在整个系统中传播。配对形成的机理与库仑电子对有效的窄能带的出现有关，该能量对具有保守的总对能量和动量。成对形成概率对有效填充因子的依赖性以大约20％（或80％）的填充因子获得。与最近邻紧密绑定模型的比较表明，远程跳变增加了相空间的体积，并具有较高的成对概率。我们推测，此处讨论的库仑电子对可能在高温超导中起作用。

图形摘要