The discovery of bilayer nickelate superconductors under high pressure has opened a new chapter in high-transition temperature (high-TC) superconductivity. Here, we report ambient-pressure superconductivity onset above the McMillan limit (40 K) in bilayer nickelate epitaxial ultrathin films. Three-unit-cell (3UC) thick La2.85Pr0.15Ni2O7 single-phase-crystalline films are grown using the gigantic-oxidative atomic-layer-by-layer epitaxy (GOALL-Epitaxy) on SrLaAlO4 substrates. Resistivity measurements and magnetic-field responses indicate onset TC = 45 K. The transition to zero resistance exhibits characteristics consistent with a Berezinskii-Kosterlitz-Thouless (BKT)-like behavior, with TBKT = 9 K. Meissner diamagnetic effect is observed at TM = 8.5 K via a mutual inductance setup, in agreement with the BKT-like transition. In-plane and out-of-plane critical magnetic fields exhibit anisotropy. Scanning transmission electron microscopy (STEM) images and X-ray reciprocal space mappings (RSMs) show that the films maintain a tetragonal phase with coherent epitaxial compressive strain ~2% in the NiO2 planes relative to the bulk. Our findings pave the way for comprehensive investigations of nickelate superconductors under ambient pressure conditions and for exploring superconductivity at higher transition temperature through strain engineering in heterostructures.
Superconductivity at the metal-insulator phase boundary in a bulk nickelate at ambient pressure
Argonne National Laboratory（阿贡国家实验室）；University of Illinois Chicago（伊利诺伊大学芝加哥分校）；School of Physics, Southeast University（东南大学物理学院）；Norfolk State University（诺福克州立大学）
Superconductivity onset above 60 K in ambient-pressure nickelate films
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）；Shanghai Jiao Tong University（上海交通大学）；Tsinghua University（清华大学）
Superconductivity and Electronic Structures of Nickelate Thin Film Superstructures
Southern University of Science and Technology（南方科技大学）；University of Science and Technology of China（中国科学技术大学）；Shanghai Jiao Tong University（上海交通大学）；Tsinghua University（清华大学）
Bulk superconductivity in quintuple-layer square-planar nickelate La6Ni5O12
University of Science and Technology of China（中国科学技术大学）；Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学先进微结构协同创新中心）
Controlling the Band Filling and the Band Width in Nickelate Superconductors
RIKEN Center for Emergent Matter Science (CEMS)（理化学研究所 emergent matter science 中心）；RIKEN Pioneering Research Institute（理化学研究所 先锋研究院）；The University of Tokyo（东京大学）；Department of Applied Physics, The University of Tokyo（东京大学 应用物理系）；Institute of Engineering Innovation, The University of Tokyo（东京大学 工程创新研究所）；Nanostructures Research Laboratory, Japan Fine Ceramics Center（日本精细陶瓷中心 纳米结构研究实验室）
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）
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）
Preparation and optimization of high-temperature superconducting Ruddlesden-Popper nickelate thin films
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）；Tsinghua University（清华大学）
Enhanced superconductivity in the compressively strained bilayer nickelate thin films by pressure
Nanjing University（南京大学）；Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Ruhr-University Bochum（波鸿鲁尔大学）
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）
Observation of flat-bottom U-shaped energy gap in high-Tc nickelate (La,Pr)3Ni2O7 thin films
Peking University（北京大学）；Hefei National Laboratory（合肥国家实验室）；Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area（粤港澳大湾区量子科学中心）；Boston College（波士顿学院）；Collaborative Innovation Center of Quantum Matter（量子物质协同创新中心）
Interlayer electronic coherence links magnetism and superconductivity in Ruddlesden-Popper nickelates
State Key Laboratory of Surface Physics and Department of Physics, Fudan University（复旦大学表面物理国家重点实验室和物理系）；Shanghai Research Center for Quantum Sciences（上海量子科学研究中心）；Institute of Nanoelectronics and Quantum Computing, Fudan University（复旦大学纳米电子与量子计算研究所）
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）
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）
A unified theory of thin film and bulk bilayer nickelates
School of Physics, Hangzhou Normal University（杭州师范大学物理学院）；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）
Signatures of a high-temperature collective electronic phase with superconductivity-like characteristics and a giant pressure effect in networks of boron-doped ultrathin carbon nanotubes
The Hong Kong University of Science and Technology（香港科技大学）；Université Grenoble Alpes, Université Toulouse, INSA Toulouse, CNRS, LNCMI, EMFL（格勒诺布尔阿尔卑斯大学、图卢兹大学、图卢兹国立理工学院、法国国家科学研究中心、低温磁强研究所、欧洲磁场实验室）；Cambridge University（剑桥大学）
Expanding the trilayer Ruddlesden-Popper nickelate family: Synthesis and characterization of Sm$_4$Ni$_3$O$_{10-δ}$ single crystals
National Laboratory of Solid State Microstructures and Department of Physics, Center for Superconducting Physics and Materials, Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学固体微结构物理国家重点实验室、物理系、超导物理与材料中心、先进微结构协同创新中心）
Single-crystal structural phase diagram of stoichiometric bilayer nickelate La3Ni2O7 under hydrostatic pressure
The University of Tokyo（东京大学）；RIKEN Center for Emergent Matter Science (CEMS)（理化学研究所 新兴物质科学中心）；Tohoku University（东北大学）；Japan Synchrotron Radiation Research Institute (JASRI)（日本同步辐射研究所）；Tokyo College, The University of Tokyo（东京大学东京学院）；Institute of Engineering Innovation, The University of Tokyo（东京大学工程创新研究所）；RIKEN Pioneering Research Institute (PRI)（理化学研究所 先驱研究 institute）
Persistent structural distortions and absent superconductivity in trilayer nickelate thin films
John A. Paulson School of Engineering and Applied Sciences, Harvard University（哈佛大学生物工程与应用科学学院）；Department of Physics, Harvard University（哈佛大学物理系）；Department of Electrical Engineering & Computer Science, Massachusetts Institute of Technology（麻省理工学院电气与计算机科学系）；School of Applied & Engineering Physics, Cornell University（康奈尔大学应用与工程物理学院）；Department of Physics, Arizona State University（亚利桑那州立大学物理系）；Cornell High Energy Synchrotron Source, Cornell University（康奈尔大学高能同步辐射光源）；Advanced Photon Source, Argonne National Laboratory（阿贡国家实验室先进光子源）
Electronic structure, dimer physics, orbital-selective behavior, and magnetic tendencies in the bilayer nickelate superconductor La$_3$Ni$_2$O$_7$ under pressure
基于{\it ab initio}技术，研究了双层La$_3$Ni$_2$O$_7$在压力下的电子结构与磁性，揭示了其由$d_{3z^2-r^2}$轨道形成的二聚体晶格、双轨道最小模型、异常的轨道间跃迁及主导的自旋条纹序。
Electronic Origin of Density Wave Orders in a Trilayer Nickelate
Beijing National Laboratory for Condensed Matter Physics, 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）；Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, School of Physics, Sun Yat-Sen University（中山大学物理学院广东省磁电物理与器件重点实验室）；Technical Institute of Physics and Chemistry, Chinese Academy of Sciences（中国科学院化学物理研究所）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）
Bridging ambient- and high-pressure superconductivity in La$_2$LnNi$_2$O$_7$ films
The University of Tokyo（东京大学）；RIKEN Center for Emergent Matter Science (CEMS)（理化学研究所 emergent matter science 中心）；Institute for Solid State Physics, The University of Tokyo（东京大学固体物理研究所）；Institute for Materials Research (IMR), Tohoku University（东北大学材料科学研究所）；Advanced Institute for Materials Research (WPI-AIMR), Tohoku University（东北大学先进材料研究高等研究院）；Tokyo College, The University of Tokyo（东京大学东京学院）
Time-reversal symmetry breaking superconductivity with electronic glass in nickelate (La, Pr, Sm)3Ni2O7 films
Peking University（北京大学）；Southern University of Science and Technology（南方科技大学）；Renmin University of China（中国人民大学）；ShanghaiTech University（上海科技大学）；Boston College（波士顿学院）；Tsinghua University（清华大学）
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
