Existing Quantum Monte Carlo studies have investigated the properties of fermions on a Lieb (CuO$_2$) lattice interacting with an on-site, or near-neighbor electron-electron coupling. Attention has focused on the interplay of such interactions with the macroscopic degeneracy of local zero energy modes, from which Bloch states can be formed to produce a flat band in which energy is independent of momentum. The resulting high density of states, in combination with the Stoner criterion, suggests that there should be pronounced instabilities to ordered phases. Indeed, a theorem by Lieb rigorously establishes the existence of ferrimagnetic order. Here we study the charge density wave phases induced by electron-phonon coupling on the Lieb lattice, as opposed to previous work on electron-electron interactions. Our key result is the demonstration of charge density wave (CDW) phases at one-third and two-thirds fillings, characterized by long-range density density correlations between doubly occupied sites on the minority or majority sublattice, and an accompanying gap. We also compute the transition temperature to the ordered phase as a function of the electron-phonon coupling.
Comment on ``Electron-phonon Vertex in the Two-dimensional One-band Hubbard Model''
In cond-mat/0306131 Huang { \em et al.}首次报道了小声子动量在电子关联引起的电子-声子耦合中占优势的数值证据。他们还报告了一个向上翻转的电子声子顶点功能的小动量的哈伯德排斥$U$足够大的$U$的功能。在这篇评论中，我们比较了他们的量子蒙特卡罗数据与分析结果的基础上从玻色子技术的通用$U$。我们关联的电子-声子顶点函数的向上翻转，在大的温度下的相分离不稳定的趋势。
Electron and phonon band-structure calculations for the antipolar SrPt$_{3}$P antiperovskite superconductor: Evidence of low-energy two-dimensional phonons
Flat band driven competing charge and spin instabilities in the altermagnet CrSb
Donostia International Physics Center (DIPC)（多诺斯蒂亚国际物理中心）；Centro de Física de Materiales (CFM-MPC), CSIC-UPV/EHU（材料物理中心，西班牙国家研究委员会/巴斯克国立大学）；Fisika Aplikatua Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU)（应用物理系，吉普斯夸工程学院，巴斯克国立大学）；Department of Applied Physics, KTH Royal Institute of Technology（皇家理工学院应用物理系）；Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences（凝聚态物理北京实验室，中国科学院物理研究所）；Swiss-Norwegian BeamLines at European Synchrotron Radiation Facility（欧洲同步辐射装置瑞士-挪威光束线）；European Synchrotron Radiation Facility (ESRF)（欧洲同步辐射装置）；Département de Physique et Institut Quantique, Université de Sherbrooke（物理系与量子研究所，舍布鲁克大学）
Mode-selective coupling of coherent phonons to the Bi2212 electronic band structure
铜酸盐超导体中含有大量的低能光学声子。利用时间分辨和角度分辨光电子能谱研究了Bi $_{2}$ Sr $_{2}$ Ca $_{0.92}$ Y $_{0.08}$ Cu $_{2}$ O $_{8+δ}$中的相干声子.在$3.94\pm 0.01$和$5.59\pm 0.06$ THz频率下观察到电子能带结构的亚meV调制。对于在3.94太赫兹的主导模式，带能量振荡的幅度弱增加的动量远离节点的函数。理论计算允许将观察到的模式识别为CuO $_{2}$衍生的$A_{1g}$声子。Bi和Sr衍生的$A_{1g}$模式，占主导地位的拉曼光谱在相关的频率范围内是不存在的，在我们的测量。这突出了耦合到近费米能级电子的声子的模式选择性，所述近费米能级电子源自CuO $_{2}$平面并决定热力学性质。
Tracking flat bands via phonon-mediated interband scattering
Materials Physics Applications–Quantum, Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室）；Center for Computational Quantum Physics, Flatiron Institute（平顿研究所）；Institute of Solid State Physics, TU Wien（维也纳工业大学固体物理研究所）
Density-matrix renormalization group study of pairing when electron-electron and electron-phonon interactions coexist: effect of the electronic band structure
