Ever since the discovery of high-temperature superconductivity in cuprates, gaining microscopic insights into the nature of pairing in strongly correlated, repulsively interacting fermionic systems has remained one of the greatest challenges in modern condensed matter physics. Following recent experiments reporting superconductivity in the bilayer nickelate La$_3$Ni$_2$O$_7$ (LNO) with remarkably high critical temperatures of $T_c = 80$ K, it has been argued that the low-energy physics of LNO can be described by the strongly correlated, mixed-dimensional bilayer $t-J$ model. Here we investigate this bilayer system and utilize density matrix renormalization group techniques to establish a thorough understanding of the model and the magnetically induced pairing through comparison to the perturbative limit of dominating inter-layer spin couplings. In particular, this allows us to explain appearing finite-size effects, firmly establishing the existence of long-range superconducting order in the thermodynamic limit that is described by the XXZ universality class of hard-core bosons constituted by $s$-wave singlet pairs. As the effective model in the perturbative limit is known to show linear resistivity above the superconducting transition temperature, we propose a pair-based interpretation of the extended strange metal phase observed in LNO. By analyzing binding energies, we predict a BEC-BCS crossover as a function of the Hamiltonian parameters, whereas LNO is anticipated to lie on the BCS side in vicinity of the transition. We find large binding energies of the order of the inter-layer coupling that suggest strikingly high critical temperatures of the Berezinskii-Kosterlitz-Thouless transition, raising the question whether (mixD) bilayer superconductors possibly facilitate critical temperatures above room temperature.
Unveiling pressurized bulk superconductivity in a trilayer nickelate Pr4Ni3O10 single crystal
ShanghaiTech University（上海科技大学）；Songshan Lake Materials Laboratory（松山湖材料实验室）；Center for High Pressure Science and Technology Advanced Research（高压科学前沿研究中心）；Institute for Shanghai Advanced Research in Physical Sciences (SHARPS)（上海物理科学研究院）；Beijing University of Technology（北京工业大学）；Japan Synchrotron Radiation Research Institute（日本同步辐射研究机构）；University of Oxford（牛津大学）；Tsinghua University（清华大学）
Bulk superconductivity up to 96 K in pressurized nickelate single crystals
State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University（山东大学晶体材料研究所）；Center for High Pressure Science and Technology Advanced Research（高压科学和技术先进研究中心）；Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments (MFree), Shanghai Advanced Research in Physical Sciences (SHARPS)（极端环境材料前沿研究上海市重点实验室（MFree），上海物理科学先进研究中心（SHARPS））；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，凝聚态物理国家实验室）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology（中国科学院纳米技术标准化与计量重点实验室，国家纳米科学中心）；Key Laboratory of Materials Physics, Ministry of Education, School of Physics, Zhengzhou University（郑州大学物理学院，教育部材料物理重点实验室）；Institute of Quantum Materials and Physics, Henan Academy of Sciences（河南省科学院量子材料与物理研究所）；NSF’s ChemMatCARS, The University of Chicago（芝加哥大学，美国国家科学基金会化学-材料束线组合站（ChemMatCARS））；School of Materials and Energy, University of Electronic Science and Technology of China（电子科技大学材料与能源学院）；Huzhou Key Laboratory of Smart and Clean Energy, Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China（电子科技大学长三角研究院（湖州），湖州市智能清洁能源重点实验室）；Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences（中国科学院上海高等研究院，上海同步辐射光源）；Japan Synchrotron Radiation Research Institute（日本同步辐射研究机构）；NanoTerasu Promotion Division, Japan Synchrotron Radiation Research Institute (JASRI)（日本同步辐射研究机构（JASRI）纳米terasu推进部）
Out-of-plane bond-order phase, superconductivity, and their competition in the $t$-$J_\parallel$-$J_\perp$ model: Possible implications for bilayer nickelates
Correlated Electronic Structure and Density-Wave Gap in Trilayer Nickelate La4Ni3O10
Tsinghua University（清华大学）；Lanzhou University（兰州大学）；Songshan Lake Materials Laboratory（松山湖材料实验室）；ShanghaiTech University（上海科技大学）；University of Oxford（牛津大学）
Strong-coupling study of the pairing mechanism in pressurized La$_3$Ni$_2$O$_7$
Beijing Institute of Technology（北京理工大学）；Hangzhou Normal University（杭州师范大学）；Xiamen University（厦门大学）；Westlake University（西湖大学）；Westlake Institute for Advanced Study（西湖高等研究院）
$^{139}$La nuclear quadrupole resonance studies of pressurized La$_4$Ni$_3$O$_{10}$
Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology（华中科技大学物理学院及武汉国家强磁场中心）；Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；Songshan Lake Materials Laboratory（松山湖材料实验室）
Intertwined Charge and Spin Density Waves in Trilayer Nickelate La$_4$Ni$_3$O$_{10}$ Revealed by $^{139}$La NQR
Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；Beijing National Laboratory for Condensed Matter Physics（北京凝聚态物理国家研究中心）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University（山东大学晶体材料研究所晶体材料国家重点实验室）；State Key Laboratory of Quantum Functional Materials, School of Physical Science and Technology, ShanghaiTech University（上海科技大学物质科学与技术学院量子功能材料国家重点实验室）；School of Physics and Astronomy, Beijing Normal University（北京师范大学物理与天文学院）；Key Laboratory of Multiscale Spin Physics, Ministry of Education, Beijing Normal University（北京师范大学多尺度自旋物理教育部重点实验室）
Distinguishing Electronic Band Structure of Single-layer and Bilayer Ruddlesden-Popper Nickelates Probed by in-situ High Pressure X-ray Absorption Near-edge Spectroscopy
Nonthermal melting and density wave instability coupled to the lattice in La$_4$Ni$_3$O$_{10}$
Central South University（中南大学）；Fudan University（复旦大学）；Shanghai Research Center for Quantum Sciences（上海量子科学研究中心）；Hefei National Laboratory（合肥国家实验室）；New Cornerstone Science Laboratory（新基石科学研究院）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）
Spin-density-wave transition in monolayer-trilayer La3Ni2O7 single crystals
ShanghaiTech University（上海科技大学）；Songshan Lake Materials Laboratory（松山湖材料实验室）；Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；Beijing National Laboratory for Condensed Matter Physics（北京凝聚态物理国家研究中心）；University of Chinese Academy of Sciences（中国科学院大学）；Center for High Pressure Science and Technology Advanced Research（高压科学先进研究发展中心）；Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments (MFree)（极端环境材料前沿研究上海市重点实验室）；Institute for Shanghai Advanced Research in Physical Sciences (SHARPS)（上海高等研究院物理科学研究所）；ShanghaiTech Laboratory for Topological Physics（上海科技大学拓扑物理实验室）；Shanghai Key Laboratory of High-resolution Electron Microscopy（高分辨电子显微学上海市重点实验室）；Department of Physics, Clarendon Laboratory, University of Oxford（牛津大学克拉伦登实验室物理系）；School of Physical Sciences, Great Bay University（大湾区大学物理科学学院）
Electronic structure and magnetic tendencies of trilayer La$_4$Ni$_3$O$_{10}$ under pressure: structural transition, molecular orbitals, and layer differentiation
Fermi-liquid transport beyond the upper critical field in superconducting La$_2$PrNi$_2$O$_7$ thin films
National Tsing Hua University（国立清华大学）；Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory（斯坦福材料能源科学研究所，SLAC国家加速器实验室）；Stanford University（斯坦福大学）；Institute for Solid State Physics, The University of Tokyo（东京大学固体物理研究所）；Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf（德累斯顿高磁场实验室（HLD-EMFL），赫尔姆霍茨中心德累斯顿-罗斯多夫）
Competing Interlayer Loop Currents and Superconductivity in the Bilayer $t$-$J_\perp$-$V$ Model
Facultad de Ciencias Exactas, Ingeniería y Agrimensura（理学院、工程学院和测量学院）；Instituto de Física Rosario (UNR-CONICET)（罗萨里奥物理研究所（UNR-CONICET））；Department of Physics, Nagoya University（名古屋大学物理学系）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；Max Planck Institute for Solid State Research（马克斯·普朗克固体研究所）
Measurement of spin dynamics in a layered nickelate using x-ray photon correlation spectroscopy: Evidence for intrinsic destabilization of incommensurate stripes at low temperatures
Structural symmetry effects on the competition of density waves and superconductivity in bilayer nickelates
Ruhr-Universität Bochum（波鸿鲁尔大学）；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研究中心））；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）
Magnetic Correlations and Pairing Tendencies of the Hybrid Stacking Nickelate Superlattice La$_7$Ni$_5$O$_{17}$ (La$_3$Ni$_2$O$_7$/La$_4$Ni$_3$O$_{10}$) under Pressure
Limits to the strain engineering of layered square-planar nickelate thin films
层状方形平面镍酸盐，Nd $_{n+1}$ Ni $_{n}$ O $_{2n+2}$，是一个有吸引力的系统，通过维度来调整方形平面镍酸盐的电子性质;事实上，最近在Nd $_{6}$ Ni $_{5}$ O $_{12}$薄膜中观察到了超导性。在这里，我们调查的作用，外延应变的竞争要求的$n=3$ Ruddlesden-Popper化合物的合成，钕$_{4}$镍$_{3}$ O $_{10}$，随后减少到正方形平面相，钕$_{4}$镍$_{3}$ O $_{8}$。我们在LaAlO $_{3}$（001）上合成了最高质量的Nd $_{4}$ Ni $_{3}$ O $_{10}$薄膜，而在NdGaO $_{3}$（110）上合成的Nd $_{4}$ Ni $_{3}$ O $_{10}$薄膜表现出拉伸应变诱导的岩盐断层，但保留了块状输运性质。在SrTiO $_{3}$（001）上的Nd $_{4}$ Ni $_{3}$ O $_{10}$中形成高密度的扩展缺陷。在LaAlO $_{3}$上还原的膜变成绝缘的并且形成压缩应变诱导的$c$轴倾斜缺陷，而在NdGaO $_{3}$上的Nd $_{4}$ Ni $_{3}$ O $_{8}$膜是金属的。这项工作提供了一种途径，以合成的Nd $_{n+1}$镍$_{n}$ O $_{2n+2}$薄膜，并设置限制的能力，应变工程师通过外延这些化…
Origin of Spin Stripes in Bilayer Nickelate La$_3$Ni$_2$O$_7$
The Chinese University of Hong Kong（香港中文大学）；Johns Hopkins University（约翰斯·霍普金斯大学）；Stanford University（斯坦福大学）；SLAC National Accelerator Laboratory（斯坦福直线加速器中心）
镍酸盐是一种丰富的材料，从绝缘磁体到超导体。但是对于化学计量材料，绝缘行为是标准的，对于大多数后过渡金属氧化物。值得注意的例外是3D钙钛矿LaNiO $_3$，一种非常规的顺磁金属，和层状Ruddlesden-Popper相R $_4$ Ni $_3$ O $_{10}$，（R=La，Pr，Nd）。后者特别有趣，因为它们表现出不寻常的金属-金属转变。在这里，我们证明，这种过渡的结果从一个不相称的密度波与电荷和磁性的字符，位于中间的行为之间的金属密度波中看到的铬金属和绝缘条纹通常发现在层状镍酸盐。因此，RPDMATHABMN Ni $_3$ O $_{10}$，其似乎是3d过渡金属氧化物中巡游自旋密度波的第一个已知实例，代表了在较高镍价下的3D金属LaNiO $_3$的顺磁性与在较低镍价下的准2D RPDMATHABMP $_{2-x}$ Sr $_x$ NiO $_4$的极化子行为之间的重要桥梁。
Non-superconducting electronic ground state in pressurized BaFe$_2$S$_3$ and BaFe$_2$S$_{2.5}$Se$_{0.5}$
本文报道了利用中子衍射、非弹性中子散射、高压同步辐射衍射和高压输运技术对自旋梯型化合物BaFe $_2$ S $_{2.5}$ Se $_{0.5}$的综合研究。我们发现BaFe $_2$ S $_{2.5}$ Se $_{0.5}$具有与BaFe $_2$ S $_3$相同的$Cmcm$结构和条纹反铁磁序，但与未掺杂系统的120 K相比，N{é}el温度降低为$T_N=98$ K，有序矩略有增加，为1.40 $μ_B$/铁。BaFe $_2$ S $_{2.5}$ Se $_{0.5}$中的低能自旋激发与在BaFe $_2$ S $_{3}$中观察到的相似。然而，与BaFe $_2$ S $_3$在低于$T_c \sim 14$ ~K和10~GPa或更高压力下的超导电性的报道不同，我们在BaFe $_2$ S $_{2.5}$ Se $_{0.5}$中没有观察到超导电性。与此相反，电阻率表现出一个上升，在低温下的压力。此外，我们还发现，为这项研究合成的BaFe $_2$ S $_3$的其他高质量样品在压力下也未能成为超导体，而是在低温下显示出类似的电阻率上升。这些结果表明，微观，样品特定的细节在确定最终的电子基态在这个自旋阶梯系统中发挥了重要作用。我们认为BaFe $_2$ S $_3$和BaFe $_2$ S $_{2.5}$ Se $_{0.5}$的低温电阻率的上升可能是由于…
Pressure-induced metal-insulator and spin-state transition in low-valence layered nickelates
从头计算预测，在零温度下的金属-绝缘体转变发生在La $_4$ Ni $_3$ O $_8$在中等压力下作为压力诱导的自旋态转变的结果。已经观察到在105 K在环境压力下从低温高自旋状态到高温低自旋状态的自旋状态转变随着压力的施加而向较低温度转移。从我们的计算中，我们发现，较小的晶胞体积有利于金属低自旋态，它变得更稳定，在5 GPa。类似的物理现象应该发生在相关化合物La $_3$ Ni $_2$ O $_6$中，但在不同的能量尺度上，这可能解释了为什么在这种材料中没有观察到跃迁。
$3d_{z^2}$ orbital delocalization and magnetic collapse in superconducting (La,Pr)$_3$Ni$_2$O$_{7-δ}$ films
Diamond Light Source（钻石光源）；National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China（中国科学技术大学核科学与技术学院和同步辐射实验室）；Southern University of Science and Technology（南方科技大学）；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和北京凝聚态物理国家研究中心）；University of Chinese Academy of Sciences（中国科学院大学）；Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area（粤港澳大湾区量子科学中心）
