Uncovering origins of heterogeneous superconductivity in La$_3$Ni$_2$O$_7$ using quantum sensors
Harvard University（哈佛大学）；Boston University（波士顿大学）；Massachusetts Institute of Technology（麻省理工学院）；Iowa State University（爱荷华州立大学）
Srinivas V. Mandyam, Esther Wang, Zhipan Wang, Bijuan Chen, Nishan C. Jayarama, Anmay Gupta, Eric A. Riesel, Valery I. Levitas, Christopher R. Laumann, Norman Y. Yao
The family of nickelate superconductors have long been explored as analogs of the high temperature cuprates. Nonetheless, the recent discovery that certain stoichiometric nickelates superconduct up to high $T_c$ under pressure came as a surprise. The mechanisms underlying the superconducting state remain experimentally unclear. In addition to the practical challenges posed by working in a high pressure environment, typical samples exhibit anomalously weak diamagnetic responses, which have been conjectured to reflect inhomogeneous `filamentary' superconducting states. We perform wide-field, high-pressure, optically detected magnetic resonance spectroscopy to image the local diamagnetic responses of as grown La$_3$Ni$_2$O$_7$ samples \emph{in situ}, using nitrogen vacancy quantum sensors embedded in the diamond anvil cell. These maps confirm significant inhomogeneity of the functional superconducting responses at the few micron scale. By spatially correlating the diamagnetic Meissner response with both the local tensorial stress environment, also imaged \emph{in situ}, and stoichiometric composition, we unravel the dominant mechanisms suppressing and enhancing superconductivity. Our wide-field technique simultaneously provides a broad view of sample behavior and excellent local sensitivity, enabling the rapid construction of multi-parameter phase diagrams from the local structure-function correlations observed at the sub-micron pixel scale.
Universal Decomposition of the Low-Frequency Conductivity Spectra of Iron-Pnictides Uncovering Fermi-Liquid Behavior
对122个铁磷族化合物的红外反射率测量表明存在两个电子子系统。由于母体材料中的自旋密度波跃迁而产生的带隙，如EuFe $_2$ As $_{2}$，负责掺杂化合物中的超导性，如Ba（Fe $_{0.92}$ Co $_{0.08})_2$ As $_{2}$和Ba（Fe $_{0.95}$ Ni $_{0.05})_2$ As $_{2}$。通过分析这种贡献的直流电阻率和散射率，发现了一个隐藏的$T^2$依赖性，表明超导性是从费米液态演化出来的。第二个子系统产生了不相干的背景，存在于所有122种化合物中，这基本上是温度无关的，但受超导转变的影响。
Possibility of Exciton Mediated Superconductivity in Nano-Sized Sn/Si Core-Shell Clusters: A Process Technology towards Heterogeneous Material in Nano-Scale
Distinguishing nodal and nonunitary superconductivity in quasiparticle interference of an Ising superconductor with Rashba spin-orbit coupling: an example of NbSe$_2$
Polar, checkerboard charge order in bilayer nickelate La3Ni2O7
The University of Tokyo（东京大学）；Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所（北京凝聚态物理国家实验室））；University of Chinese Academy of Sciences（中国科学院大学）；Japan Synchrotron Radiation Research Institute (JASRI)（日本同步辐射研究所）
Multiple charge density waves and superconductivity nucleation at antiphase domain walls in the nematic pnictide Ba$_{1-x}$Sr$_{x}$Ni$_{2}$As$_{2}$
超导性如何与电荷或电子有序相互作用是量子材料研究中心尚未解决的重大问题之一。Ba $_{1-x}$ Sr $_{x}$ Ni $_{2}$ As $_{2}$（BSNA）是一种电荷有序的磷属元素化物超导体，最近被证明在量子相变（$x_c=0.7$）附近由于电子涨落而表现出六倍的超导电性增强。然而，超导性是反常的，$0.4 < x< x_c$的电阻转变发生在比比热反常更高的温度下。利用X射线散射，我们发现了一个新的电荷密度波（CDW）在BSNA在这个组成范围。CDW与两个晶格参数的周期相当，并且不同于先前在该材料中报道的两个CDW。我们认为，反常的输运行为产生的异质超导形核在反相畴壁的CDW。我们还提出了新的数据上的不相称的CDW，以前确定为单向的，表明这是一个旋转对称的，“4 $Q$“状态与$C_4$对称性。我们的研究建立了BSNA作为一种罕见的材料，包含三个不同的CDW，和一个令人兴奋的测试平台，用于研究CDW，CDW和SC订单之间的耦合。
Electronic structures across superconductor-insulator transition in Ruddlesden-Popper bilayer nickelate films
University of Science and Technology of China（中国科学技术大学）；Hefei National Laboratory, University of Science and Technology of China（合肥国家实验室，中国科学技术大学）；Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China（微观尺度物理科学合肥国家研究中心，中国科学技术大学）；Southern University of Science and Technology（南方科技大学）；Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area（粤港澳大湾区量子科学中心）；Nanjing University（南京大学）；Shanghai Jiao Tong University（上海交通大学）；Tsinghua University（清华大学）
Resolving unconventional gap structure in kagome superconductors with hybrid microwave circuits
Max Planck Institute for Chemical Physics of Solids（马克斯·普朗克固体和化学物理研究所）；Institute of Solid State and Material Physics, Technische Universität Dresden（德累斯顿工业大学固态与材料物理研究所）；Institute of Applied Physics, Technische Universität Dresden（德累斯顿工业大学应用物理研究所）；Leibniz Institute for Solid State and Materials Research Dresden（德累斯顿莱布尼茨固体与材料研究所）；Department of Physics, University of Naples Federico II（那不勒斯费德里科二世大学物理系）；Department of Electrical Engineering and Information Technology, University of Naples Federico II（那不勒斯费德里科二世大学电气与信息工程系）
Vortex-Controlled Quasiparticle Multiplication and Self-Growth Dynamics in Superconducting Resonators
Ames National Laboratory（艾姆斯国家实验室）；Iowa State University（爱荷华州立大学）；Northwestern University（西北大学）；University of Alabama at Birmingham（阿拉巴马大学伯明翰分校）；Fermi National Accelerator Laboratory（费米国家加速器实验室）
Pressure-induced Lifshitz and quantum phase transitions in electron-doped cuprate superconductor
Center for High Pressure Science & Technology Advanced Research（高压科学前沿中心）；Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments, Shanghai Advanced Research in Physical Sciences（极端环境材料前沿研究上海市重点实验室，上海物理科学研究院）；Maryland Quantum Materials Center, Department of Physics, University of Maryland（马里兰大学量子材料中心，物理学系）
