Recently discovered Ising superconductors have garnered considerable interest due to their anomalously large in-plane upper critical fields ($B_{c2}$). However, the requisite strong spin-orbital coupling in the Ising pairing mechanism generally renders these superconductors heavy-element dominant with notably low superconducting transition temperatures ($T_c$). Here, based on the Migdal-Eliashberg theory and the mean-field Bogoliubov-de Gennes Hamiltonian, we demonstrate a significant enhancement of Ising superconductivity in monolayer NbSe$_2$ through surface fluorination, as evidenced by concomitant improvements in $T_c$ and $B_{c2}$. This enhancement arises from three predominant factors. Firstly, fluorine atoms symmetrically and stably adhere to both sides of the monolayer NbSe$_2$, thereby maintaining the out-of-plane mirror symmetry and locking carrier spins out-of-plane. Secondly, fluorination suppresses the charge density wave in monolayer NbSe$_2$ and induces a van Hove singularity in the vicinity of the Fermi level, leading to a marked increase in the number of carriers and, consequently, strengthening the electron-phonon coupling (EPC). Lastly, the appearance of fluorine-related, low-frequency phonon modes further augments the EPC. Our findings suggest a promising avenue to elevate $T_c$ in two-dimensional Ising superconductors without compromising their Ising pairing.
Scanning tunneling microscopy study of helimagnetic monolayer CrBr2 on s-wave superconductor NbSe2: a topologically trivial system due to weak interfacial coupling
Hefei National Research Center for Physical Sciences at the Microscale and Department of Physics, University of Science and Technology of China(合肥微尺度物质科学国家研究中心和物理学系,中国科学技术大学);New Cornerstone Science Laboratory, Hefei National Laboratory(新基石科学实验室,合肥国家实验室)
Protection of Ising spin-orbit coupling in bulk misfit superconductors
Pavol Jozef Šafárik University in Košice(科希策帕沃尔·约瑟夫·沙法里克大学);U.S. Naval Research Laboratory(美国海军研究实验室);Institute of Experimental Physics, Slovak Academy of Sciences(斯洛伐克科学院实验物理研究所);Univ Rennes(雷恩大学);CNRS(法国国家科学研究中心);Institut de Physique de Rennes(雷恩物理研究所);Université de Fribourg(弗里堡大学);Fribourg Center for Nanomaterials(弗里堡纳米材料中心);Institut Jean Lamour(让·拉缪尔研究所);Université de Lorraine(洛林大学);SOLEIL synchrotron(索莱尔同步辐射中心);Sorbonne Université(索邦大学);Institut des NanoSciences de Paris(巴黎纳米科学研究所);Institut des Matériaux Jean Rouxel(让·鲁克斯尔材料研究所);Université de Nantes(南特大学);Università di Trento(特伦托大学);George Mason University(乔治梅森大学)
Ising superconductivity in monolayer niobium dichalcogenide alloys
NbSe $_{2}$和NbS $_{2}$是同构的二维材料,当降低到单层极限时,它们表现出对比鲜明的超导性质。单层NbSe $_{2}$是一种Ising超导体,而单层NbS $_{2}$的超导性还没有报道。NbS $_{x}$ Se $_{2-x}$合金的超导转变温度与硫含量呈现出有趣的非单调关系,这被解释为分形超导电性的一种表现。然而,关于这一结果的几个关键问题是未知的:(1)合金的电子结构是否与母体化合物不同,(2)已被证明是突出的单层NbSe $_{2}$的自旋波动也存在于合金中?利用第一性原理计算,我们发现NbS $_{x}$ Se $_{2-x}$合金中费米能级的态密度和接近磁性的态密度都比母体化合物降低了,前者会降低相变温度,而后者会提高相变温度,我们还发现在NbSe $_{2}$中可能会形成大浓度的Se空位,这可能是磁对断裂缺陷.基于我们的结果,我们提出了NbSPDMATHABMN Se $_{2-x}$合金超导转变温度非单调行为的另一种解释,它不需要多重分形的猜想.
Kinetic Inductance of Few-Layer NbSe$_2$ in the Two-Dimensional Limit
Research Laboratory of Electronics, Massachusetts Institute of Technology(麻省理工学院电子研究实验室);Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology(麻省理工学院电气工程和计算机科学系);John A. Paulson School of Engineering and Applied Sciences, Harvard University(哈佛大学约翰·A·保尔森工程与应用科学学院);Department of Physics, Massachusetts Institute of Technology(麻省理工学院物理系);Lincoln Laboratory, Massachusetts Institute of Technology(麻省理工学院林肯实验室)
Encapsulation epitaxy of air-stable monolayer superconducting films for quantum circuits and qubits
Massachusetts Institute of Technology(麻省理工学院);Yale University(耶鲁大学);Harvard University(哈佛大学);Pohang University of Science and Technology(浦项科技大学);New York University(纽约大学)
Friedel oscillations and chiral superconductivity in monolayer NbSe$_2$
University of Regensburg(雷根斯堡大学);Donostia International Physics Center(圣塞巴斯蒂安国际物理中心);University of Silesia in Katowice(卡托维兹西里西亚大学);Centro de Física de Materiales(材料物理中心);Ikerbasque, Basque Foundation for Science(伊克拉巴斯科,巴斯克科学基金会);Wrocław University of Science and Technology(弗罗茨瓦夫科技大学)
Distinguishing nodal and nonunitary superconductivity in quasiparticle interference of an Ising superconductor with Rashba spin-orbit coupling: an example of NbSe$_2$
Degenerate monolayer Ising superconductors via chiral-achiral molecule intercalation
CIC nanoGUNE(纳米技术联合研究中心);Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Químicas (EHU)(巴斯克大学化学学院先进聚合物与材料系);Universidad del País Vasco (EHU)(巴斯克大学);Instituto de Nanociencia y Materiales de Aragón (INMA) CSIC-Universidad de Zaragoza(阿拉贡纳米科学与材料研究所);Laboratorio de Microscopías Avanzadas (LMA), Universidad de Zaragoza(萨拉戈萨大学先进显微镜实验室);Donostia International Physics Center (DIPC)(圣塞巴斯蒂安国际物理中心);Ikerbasque, Basque Foundation for Science(伊克尔巴斯基奎基金会)
Ising superconductivity in noncentrosymmetric bulk NbSe2
Pavol Jozef Šafárik University in Košice(科希策帕沃尔·约瑟夫·沙法里克大学);Institute of Experimental Physics, Slovak Academy of Sciences(斯洛伐克科学院实验物理研究所);Univ. Grenoble Alpes, CNRS, Grenoble INP*, Institut Néel(格勒诺布尔阿尔卑斯大学、法国国家科学研究中心、格勒诺布尔理工学院、内耳研究所);Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, Pheliqs(格勒诺布尔阿尔卑斯大学、法国原子能和替代能源委员会、格勒诺布尔理工学院、IRIG、Pheliqs);Institut des Matériaux Jean Rouxel, Université de Nantes and CNRS-UMR 6502(让·鲁克斯尔材料研究所、南特大学和法国国家科学研究中心联合研究单位6502)
Multigap superconductivity in Ising superconductors: The case of (LaSe)1.14(NbSe2)m misfit layer compounds
Sorbonne Université(索邦大学);CNRS-UMR 7588(法国国家科学研究中心联合研究实验室7588);Université Paris-Saclay(巴黎萨克雷大学);Centre de Nanosciences et de Nanotechnologies(纳米科学与技术中心);Institute of Experimental Physics, Slovak Academy of Sciences(斯洛伐克科学院实验物理研究所);P. J. Safarik University(帕尔沙菲里克大学);Universität Würzburg(维尔茨堡大学);Université de Nantes(南特大学);Institut des Matériaux Jean Rouxel(让·鲁克塞尔材料研究所);CNR-SPIN(意大利国家研究委员会自旋物理研究所);Università degli Studi dell’Aquila(阿奎拉大学);University of Trento(特伦托大学)
Resonant interlayer coupling in NbSe$_2$-graphite epitaxial moir{é} superlattices
SUPA, School of Physics and Astronomy, University of St Andrews(圣安德鲁斯大学物理与天文学学院);Department of Physics and Astronomy, University of Manchester(曼彻斯特大学物理与天文学系);Max Planck Institute for Chemical Physics of Solids(马克斯·普朗克固体化学物理研究所);Physics Study Program, Faculty of Science and Technology, Syarif Hidayatullah State Islamic University Jakarta(雅加达希达亚图拉伊斯兰国立大学科技理学院物理学专业);Institute for Materials Research, Tohoku University(东北大学材料科学研究所)
Renormalized q-dependent Spin Susceptibility by inverting the Random Phase Approximation: Implications for quantitative assessment of the role of spin fluctuations in 2D Ising superconductor NbSe$_{2}$
Machine learning protocol to identify pairing symmetries via quasiparticle interference imaging in Ising superconductors
Institute of Informatics, Slovak Academy of Sciences(斯洛伐克科学院信息学研究所);Faculty of Informatics and Information Technologies, Slovak University of Technology(斯洛伐克科技大学信息技术学院);Institute of Experimental Physics, Slovak Academy of Sciences(斯洛伐克科学院实验物理研究所);Institute of Physics, Pavol Jozef Šafárik University in Košice(科希策帕沃尔·约瑟夫·沙法里克大学物理研究所);New Technologies Research Centre, University of West Bohemia(西波希米亚大学新技术研究中心);Faculty of Physics, University of Belgrade(贝尔格莱德大学物理学院)