Central to the layered kagome lattice superconductors AV3Sb5 (A = K, Cs, Rb) is a cascade of novel quantum states triggered by an unconventional charge density wave (CDW) order. The three-dimensional (3D) order involves a 2x2x2 phase coherent stacking of 2x2 charge density modulations in the kagome plane at low temperatures, exhibiting a CDW energy gap and evidence for time-reversal symmetry breaking. Here we report the discovery of emergent superconductivity and primary pair density wave (PDW) at the antiphase boundaries and stacking faults of bulk CDW order. We find that the π-phase shift dislocations can naturally appear on the surface as the Cs atoms form 2x2 superstructures that are out of phase with the bulk CDW. An incipient narrow band of surface states inside bulk CDW gap emerge close to the Fermi level where a particle-hole symmetric energy gap develops. We demonstrate that the energy gap originates from a novel quasi-2D kagome superconducting state (Tc ~ 5.4 K) intertwined with bulk CDW order, exhibiting an unprecedented vortex core spectrum and spatial modulations of the superconducting gap consistent with a 4x4 PDW. Intriguingly, the 2D kagome superconductivity is shown to be tunable on and off by atomically manipulating the Cs atoms on the surface. Our findings provide fresh new insights for understanding the interplay between the unconventional CDW and superconductivity in kagome metals and a pathway for atomic manipulation and topological defects engineering of quantum many-body states in correlated materials.
Emergent Network of Josephson Junctions in a Kagome Superconductor
Huygens-Kamerlingh Onnes Laboratory, Leiden University（莱顿大学休厄斯-卡默林·昂内斯实验室）；MESA+ Institute for Nanotechnology, University of Twente（特温特大学 MESA+ 纳米技术研究所）；Materials Department, University of California Santa Barbara（加州大学圣塔芭芭拉分校材料系）；Faculty of Physics, Ludwig-Maximilians-University Munich（慕尼黑路德维希-马克西米利安大学物理学院）；Center for Nano Science (CeNS), Ludwig-Maximilians-University Munich（慕尼黑路德维希-马克西米利安大学纳米科学中心）；Munich Center for Quantum Science and Technology (MCQST), Ludwig-Maximilians- University Munich（慕尼黑量子科学与技术中心）
Thickness-driven crossover from conventional to chiral nonreciprocal superconductivity in kagome metal CsV3Sb5
National University of Singapore（新加坡国立大学）；Max Planck Institute for Chemical Physics of Solids（马克斯·普朗克固体化学物理研究所）；The Chinese University of Hong Kong（香港中文大学）；Research Center for Electronic and Optical Materials（电子与光学材料研究中心）；Research Center for Materials Nanoarchitectonics（材料纳米架构研究中心）；State Key Laboratory of Quantum Information Technologies and Materials（量子信息技术与材料国家重点实验室）；Hunan University（湖南大学）
Fermi-liquid-like phase driven by next-nearest-neighbor couplings in a lightly doped kagome-lattice $t$-$J$ model
School of Physics, Beihang University（北京航空航天大学物理学院）；School of Physics, Beijing Institute of Technology（北京理工大学物理学院）；Department of Physics and Astronomy, California State University Northridge（加州州立大学北岭分校物理与天文学系）；School of Physical Sciences, Great Bay University（大湾区大学物理科学学院）；Great Bay Institute for Advanced Study（大湾区高等研究院）
Soft Phonon Charge-Density Wave Formation in the Kagome Metal KV$_3$Sb$_5$
Zhejiang University（浙江大学）；Hangzhou Normal University（杭州师范大学）；University of Science and Technology of China（中国科学技术大学）；Zhejiang University of Technology（浙江工业大学）；Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China（中国科学院微观尺度物理科学合肥国家研究中心，中国科学技术大学）
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）
