Myasnikova A E, Zhileeva E A, Moseykin D V
Physics Faculty, Southern Federal University, Rostov-on-Don, Russia.
J Phys Condens Matter. 2018 Mar 28;30(12):125601. doi: 10.1088/1361-648X/aaad3e.
An approach to considering systems with a high concentration of correlated carriers and strong long-range electron-phonon interaction and to calculating the high-energy part of the angle-resolved photoemission spectroscopy (ARPES) spectra of such systems is suggested. Joint relaxation of strongly coupled fields-a field of correlated electrons and phonon field-after photoemission is studied to clarify the nature of characteristic features observed in the high-energy part of the ARPES spectra of cuprate superconductors. Such relaxation occurs in systems with strong predominantly long-range electron-phonon interaction at sufficiently high carrier concentration due to the coexistence of autolocalized and delocalized carriers. A simple method to calculate analytically a high-energy part of the ARPES spectrum arising is proposed. It takes advantage of using the coherent states basis for the phonon field in the polaron and bipolaron states. The approach suggested yields all the high-energy spectral features like broad Gaussian band and regions of 'vertical dispersion' being in good quantitative agreement with the experiments on cuprates at any doping with both types of carriers. Demonstrated coexistence of autolocalized and delocalized carriers in superconducting cuprates changes the idea about their ground state above the superconducting transition temperature that is important for understanding transport and magnetic properties. High density of large-radius autolocalized carriers revealed may be a key to the explanation of charge ordering in doped cuprates.
本文提出了一种考虑具有高浓度关联载流子和强长程电子 - 声子相互作用的系统的方法，以及计算此类系统的角分辨光电子能谱（ARPES）高能部分光谱的方法。研究了光发射后强耦合场——关联电子场和声子场的联合弛豫，以阐明在铜酸盐超导体的ARPES光谱高能部分观察到的特征性质。由于自局域化和离域化载流子的共存，这种弛豫发生在具有强的主要是长程电子 - 声子相互作用且载流子浓度足够高的系统中。提出了一种解析计算所产生的ARPES光谱高能部分的简单方法。该方法利用了极化子和双极化子态中声子场的相干态基。所提出的方法产生了所有高能光谱特征，如宽高斯带和“垂直色散”区域，在任何掺杂两种类型载流子的情况下，都与铜酸盐的实验在定量上有很好的一致性。在超导铜酸盐中证明的自局域化和离域化载流子的共存改变了关于其超导转变温度以上基态的观念（这对于理解输运和磁性性质很重要）。所揭示的大半径自局域化载流子的高密度可能是解释掺杂铜酸盐中电荷有序化的关键。
