Resolving unoccupied electronic states with laser ARPES in bismuth-based cuprate superconductors

钴酸铋金属-绝缘体相变的ARPES研究

ARPES Study of the Metal-Insulator Transition in Bismuth Cobaltates

利用角分辨光电子能谱（ARPES）研究了Mott-Hubbard型钴酸铋体系的金属-绝缘体相变。通过改变Pb取代量，以及通过掺杂Sr或Ba阳离子，获得绝缘至金属性质的范围。我们观察到的相干和非相干部分的光谱权重的系统变化，伴随着能量的非相干部分的移位。能带色散也表明，随着电导率的增加，在费米能级处出现了弱色散态。这些变化对应于随温度变化的电阻率行为的变化。我们解决的相干-非相干部分的性质有关的峰-谷-驼峰功能中看到的铜酸盐超导体。

高温超导体中ARPES背景信号的识别

Identifying the Background Signal in ARPES of High Temperature Superconductors

高温铜氧化物超导体的光电子能谱的一个有趣的特征是在布里渊区的未占据区域中存在大信号（称为“背景”）。在这里，我们目前的数据表明，这个信号的起源是外在的，最有可能是由于强散射的光电子。我们还提出了一种分析方法，可以用来减去背景信号。

从铜氧化物超导体的ARPES散射率中能提取玻色子耦合常数吗？

Can the bosonic coupling constant be extracted from the ARPES scattering rate in cuprate superconductors?

分析了近年来在高温超导铋酸盐\cite{Kordyuk}上获得的自能虚部的ARPES结果。通过接受将自能分成费米液体和玻色子部分的“费米玻色”{ \it划分程序}--这是在\cite{Kordyuk}中提出的，人们得到非常小的玻色子耦合常数，$λ_{B, Im} <0.2$。如果这个过程是正确的，那么标准的埃利亚什伯格理论就使得任何玻色子配对机制都变得无关紧要了。因此，我们面临着一个三难困境：（1）放弃"费米-玻色“除法程序\cite{Kordyuk} ;（2）放弃Eliashberg理论;（3）放弃在三步模型中解释ARPES数据，其中ARPES强度与准粒子谱函数$A(\mathbf{k},ω)$成正比。然而，由于在70 meV \cite{Lanzara}下从ARPES节点扭结中提取的玻色子耦合常数（测量自能的实部）比从ARPES线宽中提取的大得多，这意味着在\cite{Kordyuk}中进行的“费米-玻色”除法程序是不明确的。

Evolution of Incommensurate Superstructure and Electronic Structure with Pb Substitution in (Bi$_{2-x}$Pb$_{x}$)Sr$_2$CaCu$_2$O$_{8+δ}$ Superconductors

High-quality Bi$_{2-x}$Pb$_{x}$Sr$_2$CaCu$_2$O$_{8+δ}$ (Bi2212) single crystals have been successfully grown by the traveling solvent floating zone technique with a wide range of Pb substitution ($x=0-0.8$). The samples are characterized by transmission electron microscope (TEM) and measured by high resolution laser-based angle-resolved photoemission spectroscopy (ARPES) with different photon energies. A systematic evolution of the electronic structure and superstructure with Pb substitution has been revealed for the first time. The superstructure shows a significant change with Pb substitutio…

层镍酸盐薄膜中超导-绝缘体转变的电子结构

Electronic structures across superconductor-insulator transition in Ruddlesden-Popper bilayer nickelate films

研究通过ARPES和XAS揭示了层镍酸盐薄膜在超导-绝缘体转变中的电子结构演变，发现超导态中存在费米能级附近的相干准粒子带和高能区的非相干瀑布特征，绝缘态形成过程中相干带权重逐渐减弱，揭示了氧调控对相图中超导-绝缘体转变的电子起源。

Observation of the bands with $d_{xy}$ orbital character near the Fermi level in NdFeAs$_{1-x}$P$_{x}$O$_{0.9}$F$_{0.1}$ using angle-resolved photoemission spectroscopy

We studied the band structure of NdFeAs$_{1-x}$P$_{x}$O$_{0.9}$F$_{0.1}$ ($x$ = 0, 0.2, 0.4 and 0.6) using angle-resolved photoemission spectroscopy (ARPES) measurements. Two of the hole bands, $α_1$ $(d_{xz})$ and $α_3$ $(d_{z^2})$, were observed at the Brillouin zone center in the $P$-polarized light configuration, while the other two hole bands, $α_2$ $(d_{yz})$ and $γ$ $(d_{xy})$, were observed in the $S$-polarized alternative. The observed $γ$ band shifts downwards as $x$ increases, which is consistent with the theoretical prediction for the change in bond angle of As/P-Fe-As/P. Furthermo…