We investigate the electronic and structural properties of CuO, which shows significant deviations from the trends obeyed by other transition-metal monoxides. Using an extended Hubbard corrective functional, we uncover an orbitally ordered insulating ground state for the cubic phase of this material, which was expected but never found before. This insulating state results from a fine balance between the tendency of Cu to complete its d-shell and Hund's rule magnetism. Starting from the ground state for the cubic phase, we also study tetragonal distortions of the unit cell (recently reported in experiments), the consequent electronic reorganizations and identify the equilibrium structure. Our calculations reveal an unexpected richness of possible magnetic and orbital orders, relatively close in energy to the ground state, whose stability depends on the sign and entity of distortion.
Structural transitions in a doped lanthanum cuprate
139La NMR and relaxation measurements have been performed on La{1.8-x}Eu{0.2}Sr{x}CuO{4} (x = 0.13 and 0.2) single crystals. The temperature dependence of the 139La NMR spectra in all the structural phases (HTT -> LTO -> LTT) reveals the non-vanishing tilt angle of the CuO6 octahedra in the HTT phase, opposed to the case of La{2-x}Sr{x}CuO{4} where the tilt angle disappears immediately above the transition. Since 139La relaxation data provide evidence of the thermodynamic critical fluctuations associated with the structural phase transitions , HTT -> LTO and LTO -> LTT, we conclude that the st…
The electronic structure of La$_{1.48}$Nd$_{0.4}$Sr$_{0.12}$CuO$_4$ probed by high- and low-energy angle-resolved photoelectron spectroscopy: evolution with probing depth
Anomalous behaviors of the charge and spin degrees of freedom in the CuO double chains of PrBa$_2$Cu$_4$O$_8$
用密度矩阵重整化群方法研究了PrBa $_2$ Cu $_4$ O $_8$的CuO双链哈伯德模型的电子态.我们表明，在四分之一填充的模型具有带型和线型图案的电荷有序相的参数空间，并在之间，出现了一个广泛的区域消失的电荷间隙;后一阶段的特征是Tomonaga-Luttinger液体或金属状态的自旋间隙。我们认为PrBa $_2$ Cu $_4$ O $_8$的CuO双链的低能电子态应该是具有可能小的自旋能隙的金属态。
The Fermi surface and the role of electronic correlations in Sm$_{2-x}$Ce$_{x}$CuO$_4$
采用LDA+GTB（局域密度近似+广义紧束缚）混合方法研究了电子掺杂高$T_c$材料Sm $_{2-x}$ Ce $_{x}$ CuO $_4$的能带结构.在NMTO（$N$ -th order Muffin-Tin orbital）方法内获得了该系统的最小紧束缚模型（所谓的3带Emery模型）的参数。掺杂的色散和费米表面的电子相关的存在下的演变进行了研究，在两个制度的磁序：短程（自旋液体）和长程（反铁磁金属）。每个政权的特点是特定的拓扑结构的费米表面，我们讨论了它们与最近的实验数据。
Electronic Structure of Ce-Doped and -Undoped Nd$_2$CuO$_4$ Superconducting Thin Films Studied by Hard X-ray Photoemission and Soft X-ray Absorption Spectroscopy
Unusual electronic ground state of a prototype cuprate: band splitting of single CuO_2-plane Bi_2 Sr_(2-x) La_x CuO_(6+delta)
通过极化的原位改变，对于最佳掺杂的（x=0.4）Bi $_{2}$ Sr $_{2-x}$ La $_{x}$ CuO $_{6+δ}$，在（pi，0）点处解决了费米能级附近的Zhang-Rice单重态带的小分裂（R.Manzke等人，PRB 63，R100504（2001）。在这里，我们治疗的动量依赖性和线型的分裂带的光电发射的EDC模式具有非常高的角度和能量分辨率。在主对称线$Γ$ M的很大一部分上也可以观察到分裂成两个目标发射，给出了各个贡献的色散。由于双层效应不可能存在于这种单层材料中，因此必须在从当前理论模型导出的单粒子去除谱函数的上下文中讨论结果。最突出的是微观相分离，包括条纹相形成，共存的反铁磁和无公度电荷密度波临界波动耦合到电子（热点），甚至自旋电荷分离内的Luttinger液体图片，所有导致非费米液体的行为在正常状态下，并具有严重的后果的方式超导状态的形式。特别讨论了观察自旋子和holon激发的可能性。
Effects of Ba doping on the structural and electronic properties of La$_{2-x}$Ba$_x$CuO$_4$
采用第一性原理全能量计算方法，在虚晶近似下研究了La $_{2-x}$ Ba $_x$ CuO $_4$的结构和电子性质随Ba浓度$0 \leq x \leq 1.2$的变化.我们发现Ba掺杂诱导Cu d $_{x^{2}-y^{2}}$和d $_{z^{2}}$带向更高能量的准刚性位移。这种效应产生的费米表面拓扑结构，管理模仿ARPES动量分布图（MDM）的测量和紧束缚计算最近报道的掺杂镧基铜氧化物的重要变化。计算结果表明，当Ba掺杂量增加到0.3时，Cu d $_{z^{2}}$态在费米能级上的贡献显著增加，这对Cu d $_{x^{2}-y^{2}}$态的轨道杂化有影响，从而抑制了超导态.对于此Ba掺杂范围，没有磁性被发现。
Low-temperature electronic heat transport in La_{2-x}Sr_{x}CuO_{4} single crystals: Unusual low-energy physics in the normal and superconducting states
Doping evolution of the electronic structure in the single-layer cuprates Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+δ}$: Comparison with other single-layer cuprates
我们已经进行了角分辨光电子能谱和芯层X射线光电子能谱研究的单层铜酸盐Bi $_2$ Sr $_{2-x}$ La $_x$ CuO $_{6+δ}$（Bi 2201），并揭示了掺杂的电子结构的演变从轻掺杂到最佳掺杂区域。我们已经观察到的色散准粒子带的形成，费米“弧”的费米面的演变和化学势的移动与空穴掺杂在其他铜酸盐。Bi 2201中的掺杂演变类似于Ca $_{2-x}$ Na $_{x}$ CuO $_{2}$ Cl $_2$（Na-CCOC）中的掺杂演变，其中已经观察到朝向母绝缘体的较低哈伯德带的快速化学势偏移，但是与La $_{2-x}$ Sr $_{x}$ CuO $_{4}$（LSCO）中的掺杂演变完全不同，其中化学势不偏移，而色散带和费米弧/表面已经在轻掺杂区中的费米能级周围形成。利用紧束缚拟合定量分析了费米面形状和能带色散，推导出的次近邻跳跃积分$t'$也证实了与Na-CCOC的相似性和与LSCO的不同.
X-ray absorption spectroscopy study of the electronic and magnetic proximity effects in YBa$_2$Cu$_3$O$_{7}$/La$_{2/3}$Ca$_{1/3}$MnO$_3$ and La$_{2-x}$Sr$_x$CuO$_4$/La$_{2/3}$Ca$_{1/3}$MnO$_3$ multilayers
Electronic Structure and Superconductivity in La$_{1.55}$Sr$_{0.45}$CuO$_4$/La$_2$CuO$_4$ Artificial High-$T_c$ Superlattices Probed by Hard and Soft X-ray Spectroscopy
Temple University（天普大学）；Diamond Light Source Ltd.（钻石光源有限公司）；Advanced Light Source, Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室先进光源中心）；Max Planck Institute for Solid State Research（马克斯·普朗克固态研究所）；Institute of Crystallography, Italian National Research Council, IC-CNR（意大利国家研究委员会晶体学研究所）；Rome International Center for Materials Science Superstripes, RICMASS（罗马国际材料科学超条带研究中心）
Evolution of the electronic state through the reduction annealing in electron-doped Pr_1.3-x_La_0.7_Ce_x_CuO_4+delta_ (x=0.10) single crystals: Antiferromagnetism, Kondo effect and superconductivity
Extensive infrared spectroscopic study of CuO: signatures of strong spin-phonon interaction and structural distortion
Optical properties of single-crystal monoclinic CuO in the range 70 - 6000 \cm were studied at temperatures from 7 to 300 K. Normal reflection spectra were obtained from the (001) and (010) crystal faces thus giving for the first time separate data for the $A_{u}$ and $B_{u}$ phonon modes excited in the purely transverse way (TO modes). Mode parameters, including polarizations of the $B_{u}$ modes not determined by the crystal symmetry, were extracted by the dispersion analysis of reflectivity curves as a function of temperature. Spectra of all the components of the optical conductivity tensor…
Evidence for a charge collective mode associated with superconductivity in copper oxides from neutron and x-ray scattering measurements of La$_{2-x}$Sr$_x$CuO$_4$
Photoinduced Suppression of Superconductivity in Bi$_2$Sr$_2$Ca$_2$Cu$_3$O$_{10+δ}$
高温超导体中的超导性是通过将电荷载流子引入到含有CuO $_2$平面的铜氧化物绝缘体中来实现的。这些CuO $_2$平面的扰动通过强烈影响电子环境来抑制超导性。本文利用Cu离子在CuO $_2$平面上的光致电子改性研究了Bi $_2$ Sr $_2$ Ca $_2$ Cu $_3$ O $_{10+δ}$中局域微扰的影响。这种方法已用于抑制超导转变温度T $_c$。我们表明，我们的结果光致抑制的超导性是一致的情况下，基于钉扎的波动条纹在Bi $_2$ Sr $_2$ Ca $_2$ Cu $_3$ O $_{10+δ}$。
