IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA.
Phys Rev Lett. 2015 Mar 13;114(10):107001. doi: 10.1103/PhysRevLett.114.107001. Epub 2015 Mar 9.
In high temperature superconductors, although some phenomena such as the Mott transition (MT) at low doping are clearly driven by electron correlations, recent experimental data imply that anharmonic oxygen degrees of freedom-characteristic of perovskite materials-are playing a significant role. A key test of the role of anharmonic oxygen is to reproduce the complex cuprate phase diagram from a simple model. Here, we show that a field theory based on nonlinear coupling to anharmonic oxygens, parametrized from ab initio calculations, quantitatively reproduces the cuprate phase diagram for dopings above the MT. Pairing is mediated by renormalized oxygen vibrations transmuted into excitations of the pseudogap. The observed strong dependence of gap to transition temperature ratio on Tc also emerges from this field theory. This work suggests that including vibrational degrees of freedom is key to developing a complete understanding of the cuprates.
在高温超导体中，尽管一些现象，如低掺杂时的莫特转变 (MT)，显然是由电子相关驱动的，但最近的实验数据表明，非谐氧自由度——钙钛矿材料的特征——正在发挥重要作用。检验非谐氧作用的一个关键是从一个简单的模型中重现复杂的铜酸盐相图。在这里，我们表明，一种基于非线性耦合到非谐氧的场论，由从头计算参数化，可以定量重现 MT 以上掺杂的铜酸盐相图。配对是通过将非谐氧振动的重整化转化为赝能隙的激发来介导的。该场论也出现了观察到的能隙到转变温度比与 Tc 的强依赖性。这项工作表明，包括振动自由度是全面理解铜酸盐的关键。
