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arXiv 2401.04479cond-mat.supr-con
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强耦合电子和声子场中电荷载流子双液系统的自由能及空穴掺杂cuprates中三相的共同本质

Free energy of a two-liquid system of charge carriers in strongly coupled electron and phonon fields and common nature of three phases in hole-doped cuprates

A. E. Myasnikova, S. V. Doronkina, R. R. Arutyunyan, A. H. Dzhantemirov

AI总结:

本研究通过变分法计算强耦合电子-声子场中载流子双液系统的自由能,揭示了空穴掺杂cuprates中pseudogap、CDW和超导相的共同本质,并探讨了提高超流转变温度的途径。

摘要:

空穴掺杂cuprates表现出部分共存的pseudogap、charge density wave (CDW)和超导相。最近,由于其临界温度具有相似的掺杂依赖性,人们推测它们具有共同的本质。在CDW相中,观察到强离子晶格发生大的冻结形变。与高极化晶格中的单载流子类似,对于其中的多载流子,所有载流子的离域态与部分载流子的自局域态之间的选择,由相互作用的载流子和声子场的自由能最小值决定。应用变分方法,我们计算了具有类cuprates色散的载流子双液系统的自由能,该系统包含自局域载流子(大极化子和双极化子)液体和离域载流子的Fermi液体。将其与纯Fermi液体的自由能进行比较,并使用Bose液体理论的标准方法计算大双极化子液体中的超流转变温度,我们确定了相图中pseudogap(由(bi)polaron势对离域准粒子的影响引起)、CDW和超导性存在的区域。它们与空穴掺杂cuprates中的位置相同,并且与cuprates类似,计算出的相图形状相对于系统特性的大范围变化是稳定的。与cuprates一样,计算出的超导转变温度随晶胞中导电平面的数量增加而升高,计算出的超流密度在过掺杂时随掺杂降低,并且双极化子密度(连同双极化子等离激元能量)在最佳掺杂时饱和。所获得的结果使我们能够讨论提高大双极化子液体中超流转变温度的方法,并为研究载流态和双极化子凝聚体的性质开辟了可能性。

英文摘要:

Hole-doped cuprates demonstrate partially coexisting pseudogap, charge density wave (CDW) and superconducting phases. Recently their common nature was supposed due to similar doping dependence of their critical temperatures. In the CDW phase, a large frozen deformation of strongly ionic lattice is observed. Like for a single carrier in a highly polarizable lattice, for multiple carriers in it the choice between delocalized states of all the carriers and autolocalized states of some part of them is determined by minimum of free energy of interacting carrier and phonon fields. Applying variational approach, we calculate free energy of a two-liquid system of carriers with cuprates-like dispersion comprising liquid of autolocalized carriers (large polarons and bipolarons) and Fermi liquid of delocalized carriers. Comparing it with the free energy of pure Fermi liquid and calculating (with standard methods of Bose-liquid theory) a temperature of superfluid transition in the large-bipolaron liquid we identify areas with presence of pseudogap (caused by impact of (bi)polaron potential on delocalized quasiparticles), CDW and superconductivity in a phase diagram. They are in the same places as in hole-doped cuprates, and similarly to cuprates the shape of the calculated phase diagram is stable with respect to wide-range change of the system characteristics. Like in cuprates, the calculated temperature of the superconducting transition increases with the number of conducting planes in the unit cell, the calculated superfluid density decreases with doping at overdoping, and the bipolaron density (together with bipolaronic plasmon energy) saturates at optimal doping. The results obtained allow us to discuss ways of increasing the temperature of the superfluid transition in large-bipolaron liquid and open a possibility of studying the current-carrying state and properties of bipolaron condensate.

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