掺杂Hubbard模型是构建奇异量子多体态的典型平台之一，包括电荷序态、奇异金属和非常规超导体。虽然未掺杂和掺杂关联相已在多种扭转van der Waals材料中实验实现，但单层材料，特别是1T过渡金属二硫族化物的实验仅达到常规绝缘未掺杂区域。单层二维材料中的关联相具有比其扭转对应物高得多的相关能量尺度，使得掺杂关联单层成为高温关联量子物质的有吸引力的平台。在此，我们展示了在van der Waals二硫族化物1T-NbSe$_2$单层中实现掺杂Mott相。由于通过邻近效应向单层van der Waals衬底发生电子转移，该系统被电子掺杂，导致形成包含半满和全满格点的关联三角晶格。我们分析了半满和全满格点的分布，表明该排列不太可能仅由无序控制，并展示了竞争性非局域多体关联的存在能够解释实验中发现的电荷关联。我们的结果确立了1T-NbSe$_2$作为探索阻挫晶格中关联掺杂Mott物理的潜在单层平台。
英文摘要：
The doped Hubbard model is one of the paradigmatic platforms to engineer exotic quantum many-body states, including charge-ordered states, strange metals and unconventional superconductors. While undoped and doped correlated phases have been experimentally realized in a variety twisted van der Waals materials, experiments in monolayer materials, and in particular 1T transition metal dichalcogenides, have solely reached the conventional insulating undoped regime. Correlated phases in monolayer two-dimensional materials have much higher associated energy scales than their twisted counterparts, making doped correlated monolayers an attractive platform for high temperature correlated quantum matter. Here, we demonstrate the realization of a doped Mott phase in a van der Waals dichalcogenide 1T-NbSe$_2$ monolayer. The system is electron doped due to electron transfer to a monolayer van der Waals substrate via proximity, leading to a correlated triangular lattice with both half-filled and fully-filled sites. We analyze the distribution of the half-filled and filled sites and show the arrangement is unlikely to be controlled by disorder alone, and we show that the presence of competing non-local many-body correlations would account for the charge correlations found experimentally. Our results establish 1T-NbSe$_2$ as a potential monolayer platform to explore correlated doped Mott physics in a frustrated lattice.
Machine learning model for efficient nonthermal tuning of the charge density wave in monolayer NbSe$_2$
Ruđer Bošković Institute（鲁德·博什科维奇研究所）；Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università degli Studi di Modena e Reggio Emilia（摩德纳和雷焦艾米利亚大学物理、信息和数学科学系）；CNR NANO S3（意大利国家研究委员会纳米S3研究所）；Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford（牛津大学化学系无机化学实验室）；Centre for Advanced Laser Techniques, Institute of Physics, Zagreb（萨格勒布物理研究所先进激光技术研究中心）
Superconducting proximity effect in a strongly correlated charge-transfer insulator
School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology（北京理工大学集成电路与微电子学院，工业和信息化部低维量子结构与器件重点实验室）
Mottness in two-dimensional van der Waals Nb$_3$X$_8$ monolayers (X=Cl, Br, and I)
研究了二维范德华材料Nb $_3$ X $_8$（X=Cl，Br，I）的强电子-电子关联效应.发现Nb $_3$ X $_8$是接近强关联极限的理想体系。它们可以用半满单带哈伯德模型来描述，其中哈伯德U与带宽W之比为U/W $\approx$ 5 $\sim$ 10。用从玻色子平均场论计算了材料的Mott跃迁和磁跃迁。通过引入Mott态，发现了$d_{x^2-y^2}+id_{xy}$超导对不稳定性，并构造了一个可调的双层Hubbard系统，该系统由两个滑动Nb $_3$ X $_8$层组成.双层系统显示带状绝缘体和莫特绝缘体之间的交叉。
Correlation-driven topological phase transition from in-plane magnetized quantum anomalous Hall to Mott insulating phase in monolayer transition metal trichlorides
Dynamical control of Coulomb interactions and Hubbard bands in monolayer 1T-TaS$_2$
TU Graz（格拉茨工业大学）；Institute of Theoretical and Computational Physics, TU Graz（格拉茨大学理论与计算物理研究所）；Max Planck Institute for the Structure and Dynamics of Matter（马普物质结构与动力学研究所）
Evidence of Mott Insulator with Thermally Induced Melting Behavior in Kagome Compound Nb3Cl8
International Center for Quantum Materials, School of Physics, Peking University（北京大学物理学院量子材料国际中心）；Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology（北京理工大学物理学院先进光电量子结构测量教育部重点实验室量子物理中心）；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）；Research Center for Electronic and Optical Materials, National Institute of Material Sciences（国立材料科学研究所电子与光学材料研究中心）；Research Center for Materials Nanoarchitectonics, National Institute of Material Sciences（国立材料科学研究所材料纳米构造研究中心）；School of Materials Science and Engineering, Peking University（北京大学材料科学与工程学院）；State Key Laboratory for Mesoscopic Physics, Frontiers Science Centre for Nano-optoelectronics, School of Physics, Peking University（北京大学物理学院介观物理国家重点实验室纳米光电子前沿科学中心）；Collaborative Innovation Center of Quantum Matter（量子物质协同创新中心）
From strong to weak correlations in breathing-mode kagome van der Waals materials: Nb$_3$(F,Cl,Br,I)$_8$ as a robust and versatile platform for many-body engineering
Radboud University（拉德堡德大学）；University of Groningen（格罗宁根大学）；Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam（阿姆斯特丹大学物理学院范德瓦尔斯-泽曼研究所）；Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University（奥胡斯大学跨学科纳米科学中心（iNANO）物理与天文学系）
