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Liu J, Wang H, Shi X, Zhang X. Prediction of superconductivity in a series of tetragonal transition metal dichalcogenides. MATERIALS HORIZONS 2024; 11:2694-2700. [PMID: 38501208 DOI: 10.1039/d4mh00141a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
Transition metal dichalcogenides (TMDCs) represent a well-known material family with diverse structural phases and rich electronic properties; they are thus an ideal platform for studying the emergence and exotic phenomenon of superconductivity (SC). Herein, we propose the existence of tetragonal TMDCs with a distorted Lieb (dLieb) lattice structure and the stabilized transition metal disulfides (MS2), including dLieb-ZrS2, dLieb-NbS2, dLieb-MnS2, dLieb-FeS2, dLieb-ReS2, and dLieb-OsS2. Except for semiconducting dLieb-ZrS2 and magnetic dLieb-MnS2, the rest of metallic dLieb-MS2 was found to exhibit intrinsic SC with the transition temperature (TC) ranging from ∼5.4 to ∼13.0 K. The TC of dLieb-ReS2 and dLieb-OsS2 exceeded 10 K and was higher than that of the intrinsic SC in the known metallic TMDCs, which is attributed to the significant phonon-softening enhanced electron-phonon coupling strength. Different from the Ising spin-orbit coupling (SOC) effect in existing non-centrosymmetric TMDCs, the non-magnetic dLieb-MS2 monolayers exhibit the Dresselhaus SOC effect, which is featured by in-plane spin orientations and will give rise to the topological SC under proper conditions. In addition to enriching the structural phases of TMDCs, our work predicts a series of SC candidates with high intrinsic TC and topological non-triviality used for fault-tolerant quantum computation.
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Affiliation(s)
- Jiale Liu
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao, Shandong 266100, China.
| | - Huidong Wang
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao, Shandong 266100, China.
| | - Xiaojun Shi
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao, Shandong 266100, China.
| | - Xiaoming Zhang
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao, Shandong 266100, China.
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2
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Zhai W, Li Z, Wang Y, Zhai L, Yao Y, Li S, Wang L, Yang H, Chi B, Liang J, Shi Z, Ge Y, Lai Z, Yun Q, Zhang A, Wu Z, He Q, Chen B, Huang Z, Zhang H. Phase Engineering of Nanomaterials: Transition Metal Dichalcogenides. Chem Rev 2024; 124:4479-4539. [PMID: 38552165 DOI: 10.1021/acs.chemrev.3c00931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Crystal phase, a critical structural characteristic beyond the morphology, size, dimension, facet, etc., determines the physicochemical properties of nanomaterials. As a group of layered nanomaterials with polymorphs, transition metal dichalcogenides (TMDs) have attracted intensive research attention due to their phase-dependent properties. Therefore, great efforts have been devoted to the phase engineering of TMDs to synthesize TMDs with controlled phases, especially unconventional/metastable phases, for various applications in electronics, optoelectronics, catalysis, biomedicine, energy storage and conversion, and ferroelectrics. Considering the significant progress in the synthesis and applications of TMDs, we believe that a comprehensive review on the phase engineering of TMDs is critical to promote their fundamental studies and practical applications. This Review aims to provide a comprehensive introduction and discussion on the crystal structures, synthetic strategies, and phase-dependent properties and applications of TMDs. Finally, our perspectives on the challenges and opportunities in phase engineering of TMDs will also be discussed.
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Affiliation(s)
- Wei Zhai
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Zijian Li
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Yongji Wang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Li Zhai
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Branch of National Precious Metals Material Engineering Research Center (NPMM), City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Yao Yao
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Siyuan Li
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Lixin Wang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Hua Yang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Banlan Chi
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Jinzhe Liang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Zhenyu Shi
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Yiyao Ge
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
| | - Zhuangchai Lai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Qinbai Yun
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - An Zhang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Zhiying Wu
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Qiyuan He
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Bo Chen
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- State Key Laboratory of Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), School of Chemistry and Life Sciences, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Zhiqi Huang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Hua Zhang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Branch of National Precious Metals Material Engineering Research Center (NPMM), City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Institute for Clean Energy, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen 518057, China
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3
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Knispel T, Berges J, Schobert A, van Loon EGCP, Jolie W, Wehling T, Michely T, Fischer J. Unconventional Charge-Density-Wave Gap in Monolayer NbS 2. NANO LETTERS 2024; 24:1045-1051. [PMID: 38232959 PMCID: PMC10835735 DOI: 10.1021/acs.nanolett.3c02787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Using scanning tunneling microscopy and spectroscopy, for a monolayer of transition metal dichalcogenide H-NbS2 grown by molecular beam epitaxy on graphene, we provide unambiguous evidence for a charge density wave (CDW) with a 3 × 3 superstructure, which is not present in bulk NbS2. Local spectroscopy displays a pronounced gap on the order of 20 meV at the Fermi level. Within the gap, low-energy features are present. The gap structure with its low-energy features is at variance with the expectation for a gap opening in the electronic band structure due to a CDW. Instead, comparison with ab initio calculations indicates that the observed gap structure must be attributed to combined electron-phonon quasiparticles. The phonons in question are the elusive amplitude and phase collective modes of the CDW transition. Our findings advance the understanding of CDW mechanisms in 2D materials and their spectroscopic signatures.
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Affiliation(s)
- Timo Knispel
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany
| | - Jan Berges
- U Bremen Excellence Chair, Bremen Center for Computational Materials Science, and MAPEX Center for Materials and Processes, University of Bremen, D-28359 Bremen, Germany
| | - Arne Schobert
- I. Institute of Theoretical Physics, Universität Hamburg, D-22607 Hamburg, Germany
| | - Erik G C P van Loon
- NanoLund and Division of Mathematical Physics, Department of Physics, Lund University, SE-22100 Lund, Sweden
| | - Wouter Jolie
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany
| | - Tim Wehling
- I. Institute of Theoretical Physics, Universität Hamburg, D-22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - Thomas Michely
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany
| | - Jeison Fischer
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany
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4
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Du H, Jiang Z, Zheng J, Zhang X, Wang W, Zhang Z. Theoretical study of CDW phases for bulk NbX 2 (X = S and Se). Phys Chem Chem Phys 2024; 26:2376-2386. [PMID: 38167696 DOI: 10.1039/d3cp04426b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
In most two-dimensional transition metal chalcogenides, the superconducting phase coexists with the charge density wave (CDW) phase. There exists at least one case, i.e. bulk 2H-NbS2, that does not conform to this picture. Scientists have shown great interest in trying to experimentally find the CDW phase of bulk NbS2 since 1975. Is there any theoretically more stable thermodynamic state than its higher-temperature metal phase, especially in the case of charge injection? Theoretically more stable CDW bulk configurations (TC for 2H-NbS2 and TTs for 2H-NbSe2) with partial pseudo energy gaps were predicted through the harmonic phonon softening theory and first-principles calculations. The ratios of larger to smaller pseudo gaps around K-H segment in the Brillouin zone for CDW phases are basically equal to those of superconductivity phases for bulk 2H-NbX2 (X = S and Se). The CDW phase should coexist with its superconductor state below the critical temperature rather than the metal phase for bulk 2H-NbS2. The presence of CDW phase should be more easily observed experimentally when the injected charge reaches 0.5e/Nb18S36 for bulk 2H-NbS2. Our calculations of density of state (DOS) indicated that, during Nb atoms contracting to form the CDW phases with symmetry breaking in the in-plane direction, dominant conductive carriers are always of p-type for bulk 2H-NbS2 while the alternation of carrier type from p-type to n-type occurs for bulk 2H-NbSe2. The Fermi level continuously drops and then the M-L segment of the out-of-plane energy band emerges from the Fermi surface, which corresponds to the reversal of p-n type sign. Lifshitz transition of pocket-vanishing types occurs in the out-of-plane direction without symmetry breaking during the geometrical structural phase transition for bulk 2H-NbSe2. Our calculations have theoretically addressed the long-standing coexistence issue of CDW and superconducting phases.
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Affiliation(s)
- Hongwei Du
- Shaanxi Key Laboratory for Theoretical Physics Frontiers, Institute of Modern Physics, Northwest University, Xi'an 710069, China
| | - Zhenyi Jiang
- Shaanxi Key Laboratory for Theoretical Physics Frontiers, Institute of Modern Physics, Northwest University, Xi'an 710069, China
| | - Jiming Zheng
- Shaanxi Key Laboratory for Theoretical Physics Frontiers, Institute of Modern Physics, Northwest University, Xi'an 710069, China
| | - Xiaodong Zhang
- Shaanxi Key Laboratory for Theoretical Physics Frontiers, Institute of Modern Physics, Northwest University, Xi'an 710069, China
| | - Wenxuan Wang
- Shaanxi Key Laboratory for Theoretical Physics Frontiers, Institute of Modern Physics, Northwest University, Xi'an 710069, China
| | - Zhiyong Zhang
- Stanford Research Computing Center, Stanford University, Stanford, CA 94305, USA
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5
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Tanaka K, Zaid H, Aoki T, Deshpande A, Hojo K, Ciobanu CV, Kodambaka S. Growth of Highly Oriented (VNbMoTaW)S 2 Layers. NANO LETTERS 2024; 24:493-500. [PMID: 38148179 DOI: 10.1021/acs.nanolett.3c04521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Compositional tunability, an indispensable parameter for modifying the properties of materials, can open up new applications for van der Waals (vdW) layered materials such as transition-metal dichalcogenides (TMDCs). To date, multielement alloy TMDC layers are obtained via exfoliation from bulk polycrystalline powders. Here, we demonstrate direct deposition of high-entropy alloy disulfide, (VNbMoTaW)S2, layers with controllable thicknesses on free-standing graphene membranes and on bare and hBN-covered Al2O3(0001) substrates via ultra-high-vacuum reactive dc magnetron sputtering of the VNbMoTaW target in Kr and H2S gas mixtures. Using a combination of density functional theory calculations, Raman spectroscopy, X-ray diffraction, scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, we determine that the as-deposited layers are single-phase, 2H-structured, and 0001-oriented (V0.10Nb0.16Mo0.19Ta0.28W0.27)S2.44. Our synthesis route is general and applicable for heteroepitaxial growth of a wide variety of TMDC alloys and potentially other multielement alloy vdW compounds with the desired compositions.
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Affiliation(s)
- Koichi Tanaka
- Department of Materials Science and Engineering, University of California, Los Angeles, 410 Westwood Plaza, Los Angeles, California 90095, United States
| | - Hicham Zaid
- Department of Materials Science and Engineering, University of California, Los Angeles, 410 Westwood Plaza, Los Angeles, California 90095, United States
| | - Toshihiro Aoki
- Irvine Materials Research Institute (IMRI), University of California, Irvine, 644 Engineering Tower, Irvine, California 92697, United States
| | - Aditya Deshpande
- Department of Materials Science and Engineering, University of California, Los Angeles, 410 Westwood Plaza, Los Angeles, California 90095, United States
| | - Koki Hojo
- Graduate Department of Micro-Nano Mechanical Science and Engineering, Nagoya University, Furo-cho, Nagoya 464-8601, Japan
| | - Cristian V Ciobanu
- Department of Mechanical Engineering and Materials Science Program, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Suneel Kodambaka
- Department of Materials Science and Engineering, University of California, Los Angeles, 410 Westwood Plaza, Los Angeles, California 90095, United States
- Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
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6
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Wu S, Basak R, Li W, Kim JW, Ryan PJ, Lu D, Hashimoto M, Nelson C, Acevedo-Esteves R, Haley SC, Analytis JG, He Y, Frano A, Birgeneau RJ. Discovery of Charge Order in the Transition Metal Dichalcogenide Fe_{x}NbS_{2}. PHYSICAL REVIEW LETTERS 2023; 131:186701. [PMID: 37977621 DOI: 10.1103/physrevlett.131.186701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 09/08/2023] [Indexed: 11/19/2023]
Abstract
The Fe intercalated transition metal dichalcogenide (TMD), Fe_{1/3}NbS_{2}, exhibits remarkable resistance switching properties and highly tunable spin ordering phases due to magnetic defects. We conduct synchrotron x-ray scattering measurements on both underintercalated (x=0.32) and overintercalated (x=0.35) samples. We discover a new charge order phase in the overintercalated sample, where the excess Fe atoms lead to a zigzag antiferromagnetic order. The agreement between the charge and magnetic ordering temperatures, as well as their intensity relationship, suggests a strong magnetoelastic coupling as the mechanism for the charge ordering. Our results reveal the first example of a charge order phase among the intercalated TMD family and demonstrate the ability to stabilize charge modulation by introducing electronic correlations, where the charge order is absent in bulk 2H-NbS_{2} compared to other pristine TMDs.
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Affiliation(s)
- Shan Wu
- Department of Physics, University of California Berkeley, California 94720, USA
- Material Sciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
- Department of Physics, Santa Clara University, Santa Clara, California 95053, USA
| | - Rourav Basak
- Department of Physics, University of California San Diego, San Diego, California 92093, USA
| | - Wenxin Li
- Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Jong-Woo Kim
- Advanced Photon Source, Argonne National Laboratories, Lemont, Illinois, USA
| | - Philip J Ryan
- Advanced Photon Source, Argonne National Laboratories, Lemont, Illinois, USA
| | - Donghui Lu
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Makoto Hashimoto
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Christie Nelson
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Raul Acevedo-Esteves
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Shannon C Haley
- Department of Physics, University of California Berkeley, California 94720, USA
| | - James G Analytis
- Department of Physics, University of California Berkeley, California 94720, USA
- CIFAR Quantum Materials, CIFAR, Toronto, Ontario M5G 1M1, Canada
| | - Yu He
- Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Alex Frano
- Department of Physics, University of California San Diego, San Diego, California 92093, USA
| | - Robert J Birgeneau
- Department of Physics, University of California Berkeley, California 94720, USA
- Material Sciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
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7
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Li Y, Pu C, Zhou D. Structure, Stability, and Superconductivity of Two-Dimensional Janus NbSH Monolayers: A First-Principle Investigation. Molecules 2023; 28:5522. [PMID: 37513394 PMCID: PMC10385167 DOI: 10.3390/molecules28145522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/13/2023] [Accepted: 07/15/2023] [Indexed: 07/30/2023] Open
Abstract
Two-dimensional Janus materials have unique structural characteristics due to their lack of out-of-plane mirror symmetry, resulting in many excellent physical and chemical properties. Using first-principle calculations, we performed a detailed investigation of the possible stable structures and properties of two-dimensional Janus NbSH. We found that both Janus 1T and 2H structures are semiconductors, unlike their metallic counterparts MoSH. Furthermore, we predicted a new stable NbSH monolayer using a particle swarm optimization method combined with first-principle calculations. Interestingly, the out-of-plane mirror symmetry is preserved in this newly found 2D structure. Furthermore, the newly found NbSH is metallic and exhibits intrinsic superconducting behavior. The superconducting critical temperature is about 6.1 K under normal conditions, which is found to be very sensitive to stress. Even under a small compressive strain of 1.08%, the superconducting critical temperature increases to 9.3 K. In addition, the superconductivity was found to mainly originate from Nb atomic vibrations. Our results show the diversity of structures and properties of the two-dimensional Janus transition metal sulfhydrate materials and provide some guidelines for further investigations.
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Affiliation(s)
- Yan Li
- International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, China
| | - Chunying Pu
- Henan International Joint Laboratory of MXene Materials Microstructure, College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061, China
| | - Dawei Zhou
- Henan International Joint Laboratory of MXene Materials Microstructure, College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061, China
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8
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Meng Q, Yu F, Liu G, Zong J, Tian Q, Wang K, Qiu X, Wang C, Xi X, Zhang Y. Thickness-Dependent Evolutions of Surface Reconstruction and Band Structures in Epitaxial β-In2Se3 Thin Films. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13091533. [PMID: 37177078 PMCID: PMC10180126 DOI: 10.3390/nano13091533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 04/29/2023] [Accepted: 04/29/2023] [Indexed: 05/15/2023]
Abstract
Ferroelectric materials have received great attention in the field of data storage, benefiting from their exotic transport properties. Among these materials, the two-dimensional (2D) In2Se3 has been of particular interest because of its ability to exhibit both in-plane and out-of-plane ferroelectricity. In this article, we realized the molecular beam epitaxial (MBE) growth of β-In2Se3 films on bilayer graphene (BLG) substrates with precisely controlled thickness. Combining in situ scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES) measurements, we found that the four-monolayer β-In2Se3 is a semiconductor with a (9 × 1) reconstructed superlattice. In contrast, the monolayer β-In2Se3/BLG heterostructure does not show any surface reconstruction due to the interfacial interaction and moiré superlattice, which instead results in a folding Dirac cone at the center of the Brillouin zone. In addition, we found that the band gap of In2Se3 film decreases after potassium doping on its surface, and the valence band maximum also shifts in momentum after surface potassium doping. The successful growth of high-quality β-In2Se3 thin films would be a new platform for studying the 2D ferroelectric heterostructures and devices. The experimental results on the surface reconstruction and band structures also provide important information on the quantum confinement and interfacial effects in the epitaxial β-In2Se3 films.
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Affiliation(s)
- Qinghao Meng
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
| | - Fan Yu
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
| | - Gan Liu
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
| | - Junyu Zong
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
| | - Qichao Tian
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
| | - Kaili Wang
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
| | - Xiaodong Qiu
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
| | - Can Wang
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- School of Physics and Electronic Sciences, Changsha University of Science and Technology, Changsha 410114, China
| | - Xiaoxiang Xi
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yi Zhang
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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9
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Edwards B, Dowinton O, Hall AE, Murgatroyd PAE, Buchberger S, Antonelli T, Siemann GR, Rajan A, Morales EA, Zivanovic A, Bigi C, Belosludov RV, Polley CM, Carbone D, Mayoh DA, Balakrishnan G, Bahramy MS, King PDC. Giant valley-Zeeman coupling in the surface layer of an intercalated transition metal dichalcogenide. NATURE MATERIALS 2023; 22:459-465. [PMID: 36658327 DOI: 10.1038/s41563-022-01459-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
Spin-valley locking is ubiquitous among transition metal dichalcogenides with local or global inversion asymmetry, in turn stabilizing properties such as Ising superconductivity, and opening routes towards 'valleytronics'. The underlying valley-spin splitting is set by spin-orbit coupling but can be tuned via the application of external magnetic fields or through proximity coupling. However, only modest changes have been realized to date. Here, we investigate the electronic structure of the V-intercalated transition metal dichalcogenide V1/3NbS2 using microscopic-area spatially resolved and angle-resolved photoemission spectroscopy. Our measurements and corresponding density functional theory calculations reveal that the bulk magnetic order induces a giant valley-selective Ising coupling exceeding 50 meV in the surface NbS2 layer, equivalent to application of a ~250 T magnetic field. This energy scale is of comparable magnitude to the intrinsic spin-orbit splittings, and indicates how coupling of local magnetic moments to itinerant states of a transition metal dichalcogenide monolayer provides a powerful route to controlling their valley-spin splittings.
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Affiliation(s)
- B Edwards
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - O Dowinton
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
| | - A E Hall
- Department of Physics, University of Warwick, Coventry, United Kingdom
| | - P A E Murgatroyd
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - S Buchberger
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - T Antonelli
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - G-R Siemann
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - A Rajan
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - E Abarca Morales
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - A Zivanovic
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - C Bigi
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - R V Belosludov
- Institute for Materials Research, Tohoku University, Sendai, Japan
| | - C M Polley
- MAX IV Laboratory, Lund University, Lund, Sweden
| | - D Carbone
- MAX IV Laboratory, Lund University, Lund, Sweden
| | - D A Mayoh
- Department of Physics, University of Warwick, Coventry, United Kingdom
| | - G Balakrishnan
- Department of Physics, University of Warwick, Coventry, United Kingdom
| | - M S Bahramy
- Department of Physics and Astronomy, University of Manchester, Manchester, UK.
| | - P D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK.
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10
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Berry T, Varnava N, Ryan DH, Stewart VJ, Rasta R, Heinmaa I, Kumar N, Schnelle W, Bhandia R, Pasco CM, Armitage NP, Stern R, Felser C, Vanderbilt D, McQueen TM. Bonding and Suppression of a Magnetic Phase Transition in EuMn 2P 2. J Am Chem Soc 2023; 145:4527-4533. [PMID: 36789888 DOI: 10.1021/jacs.2c11324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Electrons in solids often adopt complex patterns of chemical bonding driven by the competition between energy gains from covalency and delocalization, and energy costs of double occupation to satisfy Pauli exclusion, with multiple intermediate states in the transition between highly localized, and magnetic, and delocalized, and nonmagnetic limits. Herein, we report a chemical pressure-driven transition from a proper Mn magnetic ordering phase transition to a Mn magnetic phase crossover in EuMn2P2 the limiting end member of the EuMn2X2 (X = Sb, As, P) family of layered materials. This loss of a magnetic ordering occurs despite EuMn2P2 remaining an insulator at all temperatures, and with a phase transition to long-range Eu antiferromagnetic order at TN ≈ 17 K. The absence of a Mn magnetic phase transition contrasts with the formation of long-range Mn order at T ≈ 130 K in isoelectronic EuMn2Sb2 and EuMn2As2. Temperature-dependent specific heat and 31P NMR measurements provide evidence for the development of short-range Mn magnetic correlations from T ≈ 250-100 K, interpreted as a precursor to covalent bond formation. Density functional theory calculations demonstrate an unusual sensitivity of the band structure to the details of the imposed Mn and Eu magnetic order, with an antiferromagnetic Mn arrangement required to recapitulate an insulating state. Our results imply a picture in which long-range Mn magnetic order is suppressed by chemical pressure, but that antiferromagnetic correlations persist, narrowing bands and producing an insulating state.
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Affiliation(s)
- Tanya Berry
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States.,Institute for Quantum Matter, William H. Miller III Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, United States.,Department of Chemistry, Princeton University, Princeton, New Jersey 08540, United States
| | - Nicodemos Varnava
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
| | - Dominic H Ryan
- Physics Department and Centre for the Physics of Materials, McGill University, 3600 University Street, Montreal, Quebec H3A 2T8, Canada
| | - Veronica J Stewart
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States.,Institute for Quantum Matter, William H. Miller III Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Riho Rasta
- National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia
| | - Ivo Heinmaa
- National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia
| | - Nitesh Kumar
- Max-Planck-Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Walter Schnelle
- Max-Planck-Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Rishi Bhandia
- Institute for Quantum Matter, William H. Miller III Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Christopher M Pasco
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States.,Institute for Quantum Matter, William H. Miller III Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - N P Armitage
- Institute for Quantum Matter, William H. Miller III Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Raivo Stern
- National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia
| | - Claudia Felser
- Max-Planck-Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - David Vanderbilt
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
| | - Tyrel M McQueen
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States.,Institute for Quantum Matter, William H. Miller III Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, United States.,Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, United States
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11
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Wines D, Choudhary K, Biacchi AJ, Garrity KF, Tavazza F. High-Throughput DFT-Based Discovery of Next Generation Two-Dimensional (2D) Superconductors. NANO LETTERS 2023; 23:969-978. [PMID: 36715314 PMCID: PMC9988690 DOI: 10.1021/acs.nanolett.2c04420] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
High-throughput density functional theory (DFT) calculations allow for a systematic search for conventional superconductors. With the recent interest in two-dimensional (2D) superconductors, we used a high-throughput workflow to screen over 1000 2D materials in the JARVIS-DFT database and performed electron-phonon coupling calculations, using the McMillan-Allen-Dynes formula to calculate the superconducting transition temperature (Tc) for 165 of them. Of these 165 materials, we identify 34 dynamically stable structures with transition temperatures above 5 K, including materials such as W2N3, NbO2, ZrBrO, TiClO, NaSn2S4, Mg2B4C2, and the previously unreported Mg2B4N2 (Tc = 21.8 K). Finally, we performed experiments to determine the Tc of selected layered superconductors (2H-NbSe2, 2H-NbS2, ZrSiS, FeSe) and discuss the measured results within the context of our DFT results. We aim that the outcome of this workflow can guide future computational and experimental studies of new and emerging 2D superconductors by providing a roadmap of high-throughput DFT data.
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Affiliation(s)
- Daniel Wines
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Kamal Choudhary
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
- Theiss Research, La Jolla, California 92037, United States
| | - Adam J Biacchi
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Kevin F Garrity
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Francesca Tavazza
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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12
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Yue B, Zhong W, Deng W, Wen T, Wang Y, Yin Y, Shan P, Wang JT, Yu X, Hong F. Insulator-to-Superconductor Transition in Quasi-One-Dimensional HfS 3 under Pressure. J Am Chem Soc 2023; 145:1301-1309. [PMID: 36579888 DOI: 10.1021/jacs.2c11184] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Various transition-metal trichalcogenides (TMTC) show unique electronic properties, such as metal-insulator transition, topological insulator, and even superconducting transition. Currently, almost all metallic TMTC compounds can show superconductivity either at ambient pressure or at high pressure. However, most TMTC compounds are semiconductors and even insulators. Does superconductivity exist in any non-metallic TMTC compound by artificial manipulation? In this work, the electronic behavior of highly insulating HfS3 has been manipulated in terms of pressure. HfS3 undergoes an insulator-to-semiconductor transition near 17 GPa with a band gap reduction of ∼1 eV. Optical absorption, Raman spectroscopy, and X-ray diffraction measurements provide consistent results, suggesting the structural origin of the electronic transition. Upon further compression, HfS3 becomes a superconductor without further structural transition. The superconducting transition occurs as early as 50.6 GPa, and the Tc reaches 8.1 K at 121 GPa, which sets a new record for TMTCs. This work reveals that all TMTCs may be superconductors and opens a new avenue to explore the abundant emergent phenomena in the TMTC material family.
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Affiliation(s)
- Binbin Yue
- Center for High Pressure Science & Technology Advanced Research, 10 East Xibeiwang Road, Haidian, Beijing 100094, China
| | - Wei Zhong
- Center for High Pressure Science & Technology Advanced Research, 10 East Xibeiwang Road, Haidian, Beijing 100094, China
| | - Wen Deng
- Center for High Pressure Science & Technology Advanced Research, 10 East Xibeiwang Road, Haidian, Beijing 100094, China
| | - Ting Wen
- Center for High Pressure Science & Technology Advanced Research, 10 East Xibeiwang Road, Haidian, Beijing 100094, China
| | - Yonggang Wang
- Center for High Pressure Science & Technology Advanced Research, 10 East Xibeiwang Road, Haidian, Beijing 100094, China
| | - Yunyu Yin
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Pengfei Shan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Jian-Tao Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China.,Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Xiaohui Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China.,Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Fang Hong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China.,Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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13
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Li YX, Yao ZJ, Yu SL, Li JX. Superconductivity and density-wave fluctuations in an extended triangular Hubbard model: an application to SnSe 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 35:045602. [PMID: 36541553 DOI: 10.1088/1361-648x/aca85e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 12/01/2022] [Indexed: 06/17/2023]
Abstract
We employ the fluctuation-exchange approximation to study the relation of superconducting pairing symmetries and density-wave fluctuations based on the extended triangular Hubbard model upon electron doping and interactions, with an possible application to the layered metal dichalcogenide SnSe2. For the case where the interactions between electrons contain only the on-site Hubbard term, the superconducting pairings are mainly mediated by spin fluctuations, and the spin-singlet pairing with thed-wave symmetry robustly dominates in the low and moderate doping levels, and ad-wave to extendeds-wave transition is observed as the electron doping reachesn = 1. When the near-neighbor site Coulomb interactions are also included, the charge fluctuations are enhanced, and the spin-triplet pairings with thep-wave andf-wave symmetries can be realized in the high and low doping levels, respectively.
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Affiliation(s)
- Yun-Xiao Li
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
| | - Zi-Jian Yao
- Department of Physics, Nanjing Normal University, Nanjing 210023, People's Republic of China
| | - Shun-Li Yu
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Jian-Xin Li
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
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14
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Zhao C, Yi X, Chen Q, Yan C, Wang S. Josephson Effect in NbS 2 van der Waals Junctions. J Phys Chem Lett 2022; 13:10811-10815. [PMID: 36378687 DOI: 10.1021/acs.jpclett.2c02927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
van der Waals (vdW) Josephson junctions can possibly accelerate the development of an advanced superconducting device that utilizes the unique properties of two-dimensional (2D) transition metal dichalcogenide (TMD) superconductors such as spin-orbit coupling and spin-valley locking. Here, we fabricate vertically stacked NbS2/NbS2 Josephson junctions using a modified all-dry transfer technique and characterize the device performance via systematic low-temperature transport measurements. The experimental results show that the superconducting transition temperature of the NbS2/NbS2 Josephson junction is 5.84 K, and the critical current density reaches 3975 A/cm2 at 2 K. Moreover, we extract a superconducting energy gap Δ = 0.58 meV, which is considerably smaller than that expected from the single band s-wave Bardeen-Cooper-Schrieffer (BCS) model (Δ = 0.89 meV).
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Affiliation(s)
- Chuanwen Zhao
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan430074, China
| | - Xin Yi
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan430074, China
| | - Qiao Chen
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan430074, China
| | - Chengyu Yan
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan430074, China
| | - Shun Wang
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan430074, China
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15
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Majed A, Kothakonda M, Wang F, Tseng EN, Prenger K, Zhang X, Persson POÅ, Wei J, Sun J, Naguib M. Transition Metal Carbo-Chalcogenide "TMCC:" A New Family of 2D Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2200574. [PMID: 35419882 DOI: 10.1002/adma.202200574] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/31/2022] [Indexed: 06/14/2023]
Abstract
Here, a new family of 2D transition metal carbo-chalcogenides (TMCCs) is reported, which can be considered a combination of two well-known families, TM carbides (MXenes) and TM dichalcogenides (TMDCs), at the atomic level. Single sheets are successfully obtained from multilayered Nb2 S2 C and Ta2 S2 C using electrochemical lithiation followed by sonication in water. The parent multilayered TMCCs are synthesized using a simple, scalable solid-state synthesis followed by a topochemical reaction. Superconductivity transition is observed at 7.55 K for Nb2 S2 C. The delaminated Nb2 S2 C outperforms both multilayered Nb2 S2 C and delaminated NbS2 as an electrode material for Li-ion batteries. Ab initio calculations predict the elastic constant of TMCC to be over 50% higher than that of TMDC.
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Affiliation(s)
- Ahmad Majed
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA, 70118, USA
| | - Manish Kothakonda
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA, 70118, USA
| | - Fei Wang
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA, 70118, USA
| | - Eric N Tseng
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, SE-581 83, Sweden
| | - Kaitlyn Prenger
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA, 70118, USA
| | - Xiaodong Zhang
- Department of Chemistry, Tulane University, New Orleans, LA, 70118, USA
| | - Per O Å Persson
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, SE-581 83, Sweden
| | - Jiang Wei
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA, 70118, USA
| | - Jianwei Sun
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA, 70118, USA
| | - Michael Naguib
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA, 70118, USA
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16
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Effect of alloying in monolayer niobium dichalcogenide superconductors. Nat Commun 2022; 13:2376. [PMID: 35501318 PMCID: PMC9061790 DOI: 10.1038/s41467-022-29213-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 03/04/2022] [Indexed: 11/13/2022] Open
Abstract
When sulfur and silicon are incorporated in monolayer 2H-NbSe2 the superconducting transition temperature, Tc, has been found to vary non-monotonically. This was assumed to be a manifestation of fractal superconductivity. Using first-principles calculations, we show that the nonmonotonic dependence of Tc is insufficient evidence for multifractality. A unifying aspect in our study are selenium vacancies in NbSe2, which are magnetic pair-breaking defects that we propose can be present in considerable concentrations in as-grown NbSe2. We show that sulfur and silicon can occupy the selenium sites and reduce the pair-breaking effect. Furthermore, when sulfur is incorporated in NbSe2, the density of states at the Fermi level and the proximity to magnetism in the alloy are both reduced compared to the parent compound. Based on our results, we propose an alternative explanation of the non-monotonic change in Tc which does not require the conjecture of multifractality. The non-monotonic behaviour of the superconducting transition temperature in NbSe2-xSx monolayer alloys has been linked to fractal superconductivity. Here, using first-principles calculations, the authors provide an alternative explanation for this behavior based on the effects of alloying and defects on the electronic structure and magnetism.
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17
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Zheng Y, Jiang X, Xue XX, Yao X, Zeng J, Chen KQ, Wang E, Feng Y. Nuclear Quantum Effects on the Charge-Density Wave Transition in NbX 2 (X = S, Se). NANO LETTERS 2022; 22:1858-1865. [PMID: 35174707 DOI: 10.1021/acs.nanolett.1c04015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Understanding the origin of charge-density wave (CDW) instability is important for manipulating novel collective electronic states. Many layered transition metal dichalcogenides (TMDs) share similarity in the structural and electronic instability, giving rise to diverse CDW phases and superconductivity. It is still puzzling that even isostructural and isoelectronic TMDs show distinct CDW features. For instance, bulk NbSe2 exhibits CDW order at low temperature, while bulk NbS2 displays no CDW instability. The CDW transitions in single-layer NbS2 and NbSe2 are also different. In the classic limit, we investigate the electron correlation effects on the dimensionality dependence of the CDW ordering. By performing ab initio path integral molecular dynamics simulations and comparative analyses, we further revealed significant nuclear quantum effects in these systems. Specifically, the quantum motion of sulfur anions significantly reduces the CDW transition temperature in both bulk and single-layer NbS2, resulting in distinct CDW features in the NbS2 and NbSe2 systems.
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Affiliation(s)
- Yueshao Zheng
- School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China
| | - Xingxing Jiang
- School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China
| | - Xiong-Xiong Xue
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105, People's Republic of China
| | - Xiaolong Yao
- School of Physics and Technology, Xinjiang University, Urumqi 830046, People's Republic of China
| | - Jiang Zeng
- School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China
| | - Ke-Qiu Chen
- School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China
| | - Enge Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Songshan Lake Materials, Institute of Physics, CAS and School of Physics, Liaoning University, Shenyang 110036, People's Republic of China
| | - Yexin Feng
- School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China
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18
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Dong Q, Pan J, Li S, Fang Y, Lin T, Liu S, Liu B, Li Q, Huang F, Liu B. Record-High Superconductivity in Transition Metal Dichalcogenides Emerged in Compressed 2H-TaS 2. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2103168. [PMID: 34936715 DOI: 10.1002/adma.202103168] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 12/17/2021] [Indexed: 06/14/2023]
Abstract
Pressure has always been an effective method for uncovering novel phenomena and properties in condensed matter physics. Here, an electrical transport study is carried on 2H-TaS2 up to ≈208 GPa, and an unexpected superconducting state (SC-II) emerging around 86.1 GPa with an initial critical temperature (Tc ) of 9.6 K is found. As pressure increases, the Tc enhances rapidly and reaches a maximum of 16.4 K at 157.4 GPa, which sets a new record for transition metal dichalcogenides (TMDs). The original superconducting state (SC-I) is found to be re-enhanced above 100 GPa after the recession around 10 GPa, and coexists with SC-II to the highest pressure applied in this work. In situ high-pressure X-ray diffraction and Hall effect measurements reveal that the occurrence of SC-II is accompanied by a structural modification and a concurrent enhancement of hole carrier density. The new high-Tc superconducting state in 2H-TaS2 can be attributed to the change of the electronic states near the Fermi surface, owing to pressure-induced interlayer modulation. It is the first time finding this remarkable superconducting state in TMDs, which not only brings a new broad of perspective on layered materials but also expands the field of pressure-modified superconductivity.
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Affiliation(s)
- Qing Dong
- State Key Laboratory of Superhard Materials, Jilin University, Changchun, 130012, China
| | - Jie Pan
- State Key Laboratory of High-Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Shujia Li
- State Key Laboratory of Superhard Materials, Jilin University, Changchun, 130012, China
| | - Yuqiang Fang
- State Key Laboratory of High-Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Tao Lin
- State Key Laboratory of Superhard Materials, Jilin University, Changchun, 130012, China
| | - Shuang Liu
- State Key Laboratory of Superhard Materials, Jilin University, Changchun, 130012, China
| | - Bo Liu
- State Key Laboratory of Superhard Materials, Jilin University, Changchun, 130012, China
| | - Quanjun Li
- State Key Laboratory of Superhard Materials, Jilin University, Changchun, 130012, China
| | - Fuqiang Huang
- State Key Laboratory of High-Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China
- State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Bingbing Liu
- State Key Laboratory of Superhard Materials, Jilin University, Changchun, 130012, China
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19
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Azizi A, Dogan M, Cain JD, Lee K, Yu X, Shi W, Glazer EC, Cohen ML, Zettl A. Experimental and Theoretical Study of Possible Collective Electronic States in Exfoliable Re-Doped NbS 2. ACS NANO 2021; 15:18297-18304. [PMID: 34739204 DOI: 10.1021/acsnano.1c07526] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Metallic transition-metal dichalcogenides (TMDs) are rich material systems in which the interplay between strong electron-electron and electron-phonon interactions often results in a variety of collective electronic states, such as charge density waves (CDWs) and superconductivity. While most metallic group V TMDs exhibit coexisting superconducting and CDW phases, 2H-NbS2 stands out with no charge ordering. Further, due to strong interlayer interaction, the preparation of ultrathin samples of 2H-NbS2 has been challenging, limiting the exploration of presumably rich quantum phenomena in reduced dimensionality. Here, we demonstrate experimentally and theoretically that light substitutional doping of NbS2 with heavy atoms is an effective approach to modify both interlayer interaction and collective electronic states in NbS2. Very low concentrations of Re dopants (<1%) make NbS2 exfoliable (down to monolayer) while maintaining its 2H crystal structure and superconducting behavior. In addition, first-principles calculations suggest that Re dopants can stabilize some native CDW patterns that are not stable in pristine NbS2.
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Affiliation(s)
- Amin Azizi
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute at the University of California, Berkeley, Berkeley, California 94720, United States
| | - Mehmet Dogan
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Jeffrey D Cain
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute at the University of California, Berkeley, Berkeley, California 94720, United States
| | - Kyunghoon Lee
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute at the University of California, Berkeley, Berkeley, California 94720, United States
| | - Xuanze Yu
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, United States
| | - Wu Shi
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute at the University of California, Berkeley, Berkeley, California 94720, United States
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200438, China
| | - Emily C Glazer
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Marvin L Cohen
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Alex Zettl
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute at the University of California, Berkeley, Berkeley, California 94720, United States
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20
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Wang Z, Cheon CY, Tripathi M, Marega GM, Zhao Y, Ji HG, Macha M, Radenovic A, Kis A. Superconducting 2D NbS 2 Grown Epitaxially by Chemical Vapor Deposition. ACS NANO 2021; 15:18403-18410. [PMID: 34756018 PMCID: PMC8614232 DOI: 10.1021/acsnano.1c07956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/03/2021] [Indexed: 06/13/2023]
Abstract
Metallic two-dimensional (2D) transition metal dichalcogenides (TMDCs) are attracting great attention because of their interesting low-temperature properties such as superconductivity, magnetism, and charge density waves (CDW). However, further studies and practical applications are being slowed down by difficulties in synthesizing high-quality materials with a large grain size and well-determined thickness. In this work, we demonstrate epitaxial chemical vapor deposition (CVD) growth of 2D NbS2 crystals on a sapphire substrate, with a thickness-dependent structural phase transition. NbS2 crystals are epitaxially aligned by the underlying c-plane sapphire resulting in high-quality growth. The thickness of NbS2 is well controlled by growth parameters to be between 1.5 and 10 nm with a large grain size of up to 500 μm. As the thickness increases, we observe in our NbS2 a transition from a metallic 3R-polytype to a superconducting 2H-polytype, confirmed by Raman spectroscopy, aberration-corrected scanning transmission electron microscopy (STEM) and electrical transport measurements. A Berezinskii-Kosterlitz-Thouless (BKT) superconducting transition occurs in the CVD-grown 2H-phase NbS2 below the transition temperature (Tc) of 3 K. Our work demonstrates thickness and phase-controllable synthesis of high-quality superconducting 2D NbS2, which is imperative for its practical applications in next-generation TMDC-based electrical devices.
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Affiliation(s)
- Zhenyu Wang
- Institute
of Electrical and Microengineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Cheol-Yeon Cheon
- Institute
of Electrical and Microengineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Mukesh Tripathi
- Institute
of Electrical and Microengineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Guilherme Migliato Marega
- Institute
of Electrical and Microengineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Yanfei Zhao
- Institute
of Electrical and Microengineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Hyun Goo Ji
- Institute
of Electrical and Microengineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Michal Macha
- Institute
of Bioengineering, École Polytechnique
Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Aleksandra Radenovic
- Institute
of Bioengineering, École Polytechnique
Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Andras Kis
- Institute
of Electrical and Microengineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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21
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Fernández-Lomana M, Wu B, Martín-Vega F, Sánchez-Barquilla R, Álvarez-Montoya R, Castilla JM, Navarrete J, Marijuan JR, Herrera E, Suderow H, Guillamón I. Millikelvin scanning tunneling microscope at 20/22 T with a graphite enabled stick-slip approach and an energy resolution below 8 μeV: Application to conductance quantization at 20 T in single atom point contacts of Al and Au and to the charge density wave of 2H-NbSe 2. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:093701. [PMID: 34598511 DOI: 10.1063/5.0059394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/21/2021] [Indexed: 06/13/2023]
Abstract
We describe a scanning tunneling microscope (STM) that operates at magnetic fields up to 22 T and temperatures down to 80 mK. We discuss the design of the STM head, with an improved coarse approach, the vibration isolation system, and efforts to improve the energy resolution using compact filters for multiple lines. We measure the superconducting gap and Josephson effect in aluminum and show that we can resolve features in the density of states as small as 8 μeV. We measure the quantization of conductance in atomic size contacts and make atomic resolution and density of states images in the layered material 2H-NbSe2. The latter experiments are performed by continuously operating the STM at magnetic fields of 20 T in periods of several days without interruption.
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Affiliation(s)
- Marta Fernández-Lomana
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Beilun Wu
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Francisco Martín-Vega
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Raquel Sánchez-Barquilla
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Rafael Álvarez-Montoya
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - José María Castilla
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - José Navarrete
- SEGAINVEX, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | | | - Edwin Herrera
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Hermann Suderow
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Isabel Guillamón
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
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22
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Liu X, Chong YX, Sharma R, Davis JCS. Discovery of a Cooper-pair density wave state in a transition-metal dichalcogenide. Science 2021. [DOI: 10.1126/science.abd4607] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Imaging an exotic state
Among the most intriguing of the many phases of cuprate superconductors is the so-called pair density wave (PDW) state. PDW is characterized by a spatially modulated density of Cooper pairs and can be detected with a scanning tunneling microscope equipped with a superconducting tip. Liu
et al.
used Josephson tunneling microscopy, modified for the task, to detect PDW in niobium diselenide, a superconductor with a layered hexagonal structure. The PDW state is expected to appear in other transition metal dichalcogenides as well.
Science
, abd4607, this issue p.
1447
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Affiliation(s)
- Xiaolong Liu
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14850, USA
| | - Yi Xue Chong
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14850, USA
| | - Rahul Sharma
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14850, USA
- Department of Physics, University of Maryland, College Park, MD 20740, USA
| | - J. C. Séamus Davis
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14850, USA
- Department of Physics, University College Cork, Cork T12 R5C, Ireland
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
- Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, UK
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23
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Campi D, Kumari S, Marzari N. Prediction of Phonon-Mediated Superconductivity with High Critical Temperature in the Two-Dimensional Topological Semimetal W 2N 3. NANO LETTERS 2021; 21:3435-3442. [PMID: 33856216 DOI: 10.1021/acs.nanolett.0c05125] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Two-dimensional superconductors attract great interest both for their fundamental physics and for their potential applications, especially in the rapidly growing field of quantum computing. Despite intense theoretical and experimental efforts, materials with a reasonably high transition temperature are still rare. Even more rare are those that combine superconductivity with a nontrivial band topology that could potentially give rise to exotic states of matter. Here, we predict a remarkably high superconducting critical temperature of 21 K in the easily exfoliable, topologically nontrivial 2D semimetal W2N3. By studying its electronic and superconducting properties as a function of doping and strain, we also find large changes in the electron-phonon interactions that make this material a unique platform to study different coupling regimes and test the limits of current theories of superconductivity. Last, we discuss the possibility of tuning the material to achieve coexistence of superconductivity and topologically nontrivial edge states.
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Affiliation(s)
- Davide Campi
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Simran Kumari
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Nicola Marzari
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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24
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Witteveen C, Górnicka K, Chang J, Månsson M, Klimczuk T, von Rohr FO. Polytypism and superconductivity in the NbS 2 system. Dalton Trans 2021; 50:3216-3223. [PMID: 33576758 DOI: 10.1039/d0dt03636f] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report on the phase formation and the superconducting properties in the NbS2 system. Specifically, we have performed a series of standardized solid-state syntheses in this system, which allow us to establish a comprehensive synthesis map for the formation of the two polytypes 2H-NbS2 and 3R-NbS2, respectively. We show that the identification of two polytypes by means of X-ray diffraction is not always unambiguous. Our physical property measurements on a phase-pure sample of 3R-NbS2, on a phase-pure sample of 2H-NbS2, and a mixed phase sample confirm earlier reports that 2H-NbS2 is a bulk superconductor and that 3R-NbS2 is not a superconductor above T = 1.75 K. Our results clearly show that specific heat measurements, as true bulk measurements, are crucial for the identification of superconducting materials in this and related systems. Our results indicate that for the investigation of van der Waals materials great care has to be taken on choosing the synthesis conditions for obtaining phase pure samples.
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Affiliation(s)
- Catherine Witteveen
- Department of Chemistry, University of Zürich, Winterthurerstr. 190, 8057 Zürich, Switzerland. and Department of Physics, University of Zürich, Winterthurerstr. 190, 8057 Zürich, Switzerland
| | - Karolina Górnicka
- Department of Solid State Physics, Gdansk University of Technology, 80-233 Gdansk, Poland and Advanced Materials Centre, Gdansk University of Technology, ul. Narutowicza 11/12, 80-233 Gdansk, Poland
| | - Johan Chang
- Department of Physics, University of Zürich, Winterthurerstr. 190, 8057 Zürich, Switzerland
| | - Martin Månsson
- Department of Applied Physics, KTH Royal Institute of Technology, Roslagstullsbacken 21, SE-106 91 Stockholm, Sweden
| | - Tomasz Klimczuk
- Department of Solid State Physics, Gdansk University of Technology, 80-233 Gdansk, Poland and Advanced Materials Centre, Gdansk University of Technology, ul. Narutowicza 11/12, 80-233 Gdansk, Poland
| | - Fabian O von Rohr
- Department of Chemistry, University of Zürich, Winterthurerstr. 190, 8057 Zürich, Switzerland. and Department of Physics, University of Zürich, Winterthurerstr. 190, 8057 Zürich, Switzerland
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25
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Fan S, Neal S, Won C, Kim J, Sapkota D, Huang F, Yang J, Mandrus DG, Cheong SW, Haraldsen JT, Musfeldt JL. Excitations of Intercalated Metal Monolayers in Transition Metal Dichalcogenides. NANO LETTERS 2021; 21:99-106. [PMID: 33264028 DOI: 10.1021/acs.nanolett.0c03292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We combine Raman scattering spectroscopy and lattice dynamics calculations to reveal the fundamental excitations of the intercalated metal monolayers in the FexTaS2 (x = 1/4, 1/3) family of materials. Both in- and out-of-plane modes are identified, each of which has trends that depend upon the metal-metal distance, the size of the van der Waals gap, and the metal-to-chalcogenide slab mass ratio. We test these trends against the response of similar systems, including Cr-intercalated NbS2 and RbFe(SO4)2, and demonstrate that the metal monolayer excitations are both coherent and tunable. We discuss the consequences of intercalated metal monolayer excitations for material properties and developing applications.
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Affiliation(s)
- Shiyu Fan
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Sabine Neal
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Choongjae Won
- Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Jaewook Kim
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
- Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854, United States
- Korea Atomic Energy Research Institute, Daejeon 34057, Republic of Korea
| | - Deepak Sapkota
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Feiting Huang
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
- Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854, United States
| | - Junjie Yang
- Department of Physics, New Jersey Institute of Technology, Newark, New Jersey 07102, United States
| | - David G Mandrus
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Sang-Wook Cheong
- Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
- Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854, United States
| | - Jason T Haraldsen
- Department of Physics, University of North Florida, Jacksonville, Florida 32224, United States
| | - Janice L Musfeldt
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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26
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Zhang L, Tang Y, Khan AR, Hasan MM, Wang P, Yan H, Yildirim T, Torres JF, Neupane GP, Zhang Y, Li Q, Lu Y. 2D Materials and Heterostructures at Extreme Pressure. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2002697. [PMID: 33344136 PMCID: PMC7740103 DOI: 10.1002/advs.202002697] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/03/2020] [Indexed: 06/02/2023]
Abstract
2D materials possess wide-tuning properties ranging from semiconducting and metallization to superconducting, etc., which are determined by their structure, empowering them to be appealing in optoelectronic and photovoltaic applications. Pressure is an effective and clean tool that allows modifications of the electronic structure, crystal structure, morphologies, and compositions of 2D materials through van der Waals (vdW) interaction engineering. This enables an insightful understanding of the variable vdW interaction induced structural changes, structure-property relations as well as contributes to the versatile implications of 2D materials. Here, the recent progress of high-pressure research toward 2D materials and heterostructures, involving graphene, boron nitride, transition metal dichalcogenides, 2D perovskites, black phosphorene, MXene, and covalent-organic frameworks, using diamond anvil cell is summarized. A detailed analysis of pressurized structure, phonon dynamics, superconducting, metallization, doping together with optical property is performed. Further, the pressure-induced optimized properties and potential applications as well as the vision of engineering the vdW interactions in heterostructures are highlighted. Finally, conclusions and outlook are presented on the way forward.
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Affiliation(s)
- Linglong Zhang
- Institute of Microscale OptoelectronicsCollege of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen518060China
- Research School of Electrical, Energy and Materials EngineeringCollege of Engineering and Computer ScienceThe Australian National UniversityCanberraACT2601Australia
| | - Yilin Tang
- Research School of Electrical, Energy and Materials EngineeringCollege of Engineering and Computer ScienceThe Australian National UniversityCanberraACT2601Australia
| | - Ahmed Raza Khan
- Research School of Electrical, Energy and Materials EngineeringCollege of Engineering and Computer ScienceThe Australian National UniversityCanberraACT2601Australia
| | - Md Mehedi Hasan
- Research School of Electrical, Energy and Materials EngineeringCollege of Engineering and Computer ScienceThe Australian National UniversityCanberraACT2601Australia
| | - Ping Wang
- Research School of Electrical, Energy and Materials EngineeringCollege of Engineering and Computer ScienceThe Australian National UniversityCanberraACT2601Australia
| | - Han Yan
- Research School of Electrical, Energy and Materials EngineeringCollege of Engineering and Computer ScienceThe Australian National UniversityCanberraACT2601Australia
| | - Tanju Yildirim
- Research School of Electrical, Energy and Materials EngineeringCollege of Engineering and Computer ScienceThe Australian National UniversityCanberraACT2601Australia
| | - Juan Felipe Torres
- Research School of Electrical, Energy and Materials EngineeringCollege of Engineering and Computer ScienceThe Australian National UniversityCanberraACT2601Australia
| | - Guru Prakash Neupane
- Research School of Electrical, Energy and Materials EngineeringCollege of Engineering and Computer ScienceThe Australian National UniversityCanberraACT2601Australia
| | - Yupeng Zhang
- Institute of Microscale OptoelectronicsCollege of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen518060China
| | - Quan Li
- International Center for Computational Methods and SoftwareCollege of PhysicsJilin UniversityChangchun130012China
| | - Yuerui Lu
- Research School of Electrical, Energy and Materials EngineeringCollege of Engineering and Computer ScienceThe Australian National UniversityCanberraACT2601Australia
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27
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Devarakonda A, Inoue H, Fang S, Ozsoy-Keskinbora C, Suzuki T, Kriener M, Fu L, Kaxiras E, Bell DC, Checkelsky JG. Clean 2D superconductivity in a bulk van der Waals superlattice. Science 2020; 370:231-236. [DOI: 10.1126/science.aaz6643] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 08/21/2020] [Indexed: 11/02/2022]
Abstract
Advances in low-dimensional superconductivity are often realized through improvements in material quality. Apart from a small group of organic materials, there is a near absence of clean-limit two-dimensional (2D) superconductors, which presents an impediment to the pursuit of numerous long-standing predictions for exotic superconductivity with fragile pairing symmetries. We developed a bulk superlattice consisting of the transition metal dichalcogenide (TMD) superconductor 2H-niobium disulfide (2H-NbS2) and a commensurate block layer that yields enhanced two-dimensionality, high electronic quality, and clean-limit inorganic 2D superconductivity. The structure of this material may naturally be extended to generate a distinct family of 2D superconductors, topological insulators, and excitonic systems based on TMDs with improved material properties.
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Affiliation(s)
- A. Devarakonda
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - H. Inoue
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - S. Fang
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - C. Ozsoy-Keskinbora
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - T. Suzuki
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - M. Kriener
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - L. Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - E. Kaxiras
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - D. C. Bell
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Center for Nanoscale Systems, Harvard University, Cambridge, MA 02138, USA
| | - J. G. Checkelsky
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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28
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Nobukane H, Tabata Y, Kurosawa T, Sakabe D, Tanda S. Coexistence of the Kondo effect and spin glass physics in Fe-doped NbS 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:165803. [PMID: 31842001 DOI: 10.1088/1361-648x/ab622a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report the coexistence of the Kondo effect and spin glass behavior in Fe-doped NbS2 single crystals. The Fe x NbS2 shows the resistance minimum and negative magnetoresistance due to the Kondo effect, and exhibits no superconducting behavior at low temperatures. The resistance curve follows a numerical renormalization-group theory using the Kondo temperature [Formula: see text] K for x = 0.01 as evidence of Kondo effect. Scanning tunneling microscope/spectroscopy (STM/STS) revealed the presence of Fe atoms near sulfur atoms and asymmetric spectra. The magnetic susceptibility exhibits a feature of spin glass. The static critical exponents determined by the universal scaling of the nonlinear part of the susceptibility suggest a three-dimensional Heisenberg spin glass. The doped-Fe atoms in the intra- and inter-layers revealed by the x-ray result can realize the coexistence of the Kondo effect and spin glass.
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Affiliation(s)
- H Nobukane
- Department of Physics, Hokkaido University, Sapporo, 060-0810, Japan. Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan
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29
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Liebhaber E, Acero González S, Baba R, Reecht G, Heinrich BW, Rohlf S, Rossnagel K, von Oppen F, Franke KJ. Yu-Shiba-Rusinov States in the Charge-Density Modulated Superconductor NbSe 2. NANO LETTERS 2020; 20:339-344. [PMID: 31842547 DOI: 10.1021/acs.nanolett.9b03988] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
NbSe2 is a remarkable superconductor in which charge-density order coexists with pairing correlations at low temperatures. Here, we study the interplay of magnetic adatoms and their Yu-Shiba-Rusinov (YSR) bound states with the charge density order. Exploiting the incommensurate nature of the charge-density wave (CDW), our measurements provide a thorough picture of how the CDW affects both the energies and the wave functions of the YSR states. Key features of the dependence of the YSR states on adsorption site relative to the CDW are explained by model calculations. Several properties make NbSe2 a promising substrate for realizing topological nanostructures. Our results will be important in designing such systems.
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Affiliation(s)
| | | | | | | | | | - Sebastian Rohlf
- Ruprecht-Haensel-Labor and Institut für Experimentelle und Angewandte Physik , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
| | - Kai Rossnagel
- Ruprecht-Haensel-Labor and Institut für Experimentelle und Angewandte Physik , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
- Deutsches Elektronen-Synchrotron DESY , 22607 Hamburg , Germany
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30
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Kim Y, Kwon KC, Kang S, Kim C, Kim TH, Hong SP, Park SY, Suh JM, Choi MJ, Han S, Jang HW. Two-Dimensional NbS 2 Gas Sensors for Selective and Reversible NO 2 Detection at Room Temperature. ACS Sens 2019; 4:2395-2402. [PMID: 31339038 DOI: 10.1021/acssensors.9b00992] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Transition metal dichalcogenides (TMDs) have attracted enormous attention in diverse research fields. Especially, gas sensors are considered in a promising application exploiting TMDs. However, the studies are confined to only major TMDs such as MoS2 and WS2. Particularly, the chemoresistive sensing properties of two-dimensional (2D) NbS2 have never been explored. For the first time, we report room temperature NO2 sensing characteristics of 2D NbS2 nanosheets and the sensing mechanisms using first-principles calculations based on density functional theory. The results demonstrate that the NbS2 edges possessing different configurations depending on synthetic conditions differ in the sensing ability of the TMD nanosheets. This study not only broadens the potential of 2D NbS2 for gas sensing applications, but also presents the important role of edge configuration of TMDs depending on synthetic conditions for further studies.
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Affiliation(s)
- Yeonhoo Kim
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, United States
| | - Ki Chang Kwon
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
- School of Chemical Engineering and Materials Science, Integrative Research Center for Two-Dimensional Functional Materials, Institute of Interdisciplinary Convergence Research, Chung-Ang University, Seoul 06974, Republic of Korea
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Sungwoo Kang
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Changyeon Kim
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Tae Hoon Kim
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Seung-Pyo Hong
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Seo Yun Park
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Jun Min Suh
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Min-Ju Choi
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Seungwu Han
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Ho Won Jang
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
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31
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Xu R, Wang X, Zheng Z, Ye S, Xu K, Lei L, Hussain S, Pang F, Liu X, Li YJ, Sugawara Y, Ji W, Xie L, Cheng Z. Interfacial water intercalation-induced metal-insulator transition in NbS 2/BN heterostructure. NANOTECHNOLOGY 2019; 30:205702. [PMID: 30716728 DOI: 10.1088/1361-6528/ab0452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Interfacial engineering, such as molecule intercalation, can modify properties and optimize performance of van der Waals heterostructures and their devices. Here, we investigated the pristine and water molecule intercalated heterointerface of niobium disulphide (NbS2) on hexagonal boron nitride (h-BN) (NbS2/BN) using advanced atomic force microscopy (AFM), and observed the metal-insulator transition (MIT) of first layer (1L-) of NbS2 induced by water molecule intercalation. In pristine sample, interfacial charge transfers were confirmed by the direct detection of trapped static charges at the post-exposed h-BN surface, produced by mechanically peeling off the 1L-NbS2 from the substrate. The interfacial charge transfers facilitate the intercalation of water molecules at the heterointerface. The intercalated water layers make a MIT of 1L-NbS2, while the pristine metallic state of the following NbS2 layers remains preserved. This work is of great significance to help understand the interfacial properties of 2D metal/insulator heterostructures and can pave the way for further preparation of an ultrathin transistor.
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Affiliation(s)
- Rui Xu
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, People's Republic of China. CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
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32
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Structural Evolution and Chemical Bonding in Bi-nuclear Niobium Sulfide Clusters: Nb2S
n
−/0
(n = 4–7). J CLUST SCI 2019. [DOI: 10.1007/s10876-019-01532-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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33
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Bai W, Li P, Ju S, Xiao C, Shi H, Wang S, Qin S, Sun Z, Xie Y. Monolayer Behavior of NbS 2 in Natural van der Waals Heterostructures. J Phys Chem Lett 2018; 9:6421-6425. [PMID: 30351949 DOI: 10.1021/acs.jpclett.8b02781] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Monolayer transition metal dichalcogenides (TMDs) constitute an important family of materials with many intriguing properties and applications. The ability to achieve large-size and high-quality monolayer TMDs is the key prerequisite toward a deep understanding and practical application of TMDs in electronics and optoelectronics. Here, on the basis of high-resolution angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy/spectroscopy (STM/STS), we find a monolayer NbS2-dominated Fermi-level feature in a misfit compound, which is a type of natural heterostructures. Considering the infrequency of the synthesis approach and electronic properties of the NbS2 monolayer, our results cannot only provide direct insight into the electronic structure of van der Waals heterostructures (VDWHs) but also shed light on the way toward rationally investigating the monolayer TMDs, which are hardly obtained and studied.
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Affiliation(s)
- Wei Bai
- Hefei National Laboratory for Physical Sciences at the Microscale , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
| | - Pengju Li
- Hefei National Laboratory for Physical Sciences at the Microscale , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
- ICQD, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic China
| | - Sailong Ju
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei , Anhui 230029 , People's Republic of China
| | - Chong Xiao
- Hefei National Laboratory for Physical Sciences at the Microscale , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
| | - Haohao Shi
- Hefei National Laboratory for Physical Sciences at the Microscale , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
- ICQD, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic China
| | - Sheng Wang
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei , Anhui 230029 , People's Republic of China
| | - Shengyong Qin
- Hefei National Laboratory for Physical Sciences at the Microscale , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
- ICQD, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic China
| | - Zhe Sun
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei , Anhui 230029 , People's Republic of China
| | - Yi Xie
- Hefei National Laboratory for Physical Sciences at the Microscale , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
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34
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Ma Y, Ajayan PM, Yang S, Gong Y. Recent Advances in Synthesis and Applications of 2D Junctions. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1801606. [PMID: 30073751 DOI: 10.1002/smll.201801606] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/15/2018] [Indexed: 06/08/2023]
Abstract
Recent progress in the methods of integration of 2D materials is reviewed. Integrated 2D circuits are one of the most promising candidates for advanced electronics and flexible devices. Specifically, methods such as mechanical transfer, chemical vapor deposition growth, high temperature conversion, phase engineering, surface doping, electrostatic doping, and so on to fabricate 2D heterostructures are discussed in detail. Applications of these integrated 2D heterostructures in p-n junctions, ohmic contact, high-performance transistors, and phototransistors are also highlighted. Finally, challenges and opportunities of methods to integrate 2D materials are proposed.
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Affiliation(s)
- Yang Ma
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Pulickel M Ajayan
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Shubin Yang
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Yongji Gong
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
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35
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Lian CS, Si C, Duan W. Unveiling Charge-Density Wave, Superconductivity, and Their Competitive Nature in Two-Dimensional NbSe 2. NANO LETTERS 2018; 18:2924-2929. [PMID: 29652158 DOI: 10.1021/acs.nanolett.8b00237] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Recently, charge-density wave (CDW) and superconductivity are observed to coexist in atomically thin metallic NbSe2. Lacking of knowledge on the structural details of CDW, however, prevents us to explore its interplay with superconductivity. Using first-principles calculations, we identify the ground state 3 × 3 CDW atomic structure of monolayer NbSe2, which is characterized by the formation of triangular Nb clusters and shows a scanning tunnelling microscopy (STM) image and Raman CDW modes in good agreement with experiments. We further demonstrate that from bulk to monolayer NbSe2, as the layer thickness decreases, the CDW order is gradually enhanced with rising energy gain and strengthened Fermi surface gapping, while superconductivity is weakened due to the increasingly reduced Fermi level density of states in the CDW state. These results well explain the observed opposite thickness dependencies of CDW and superconducting transition temperatures and uncover the nature of competitive interaction between the two collective orders in two-dimensional NbSe2.
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Affiliation(s)
- Chao-Sheng Lian
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics , Tsinghua University , Beijing 100084 , People's Republic of China
| | - Chen Si
- School of Materials Science and Engineering , Beihang University , Beijing 100191 , People's Republic of China
| | - Wenhui Duan
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics , Tsinghua University , Beijing 100084 , People's Republic of China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , People's Republic of China
- Institute for Advanced Study , Tsinghua University , Beijing 100084 , People's Republic of China
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36
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Shin HG, Yoon HS, Kim JS, Kim M, Lim JY, Yu S, Park JH, Yi Y, Kim T, Jun SC, Im S. Vertical and In-Plane Current Devices Using NbS 2/n-MoS 2 van der Waals Schottky Junction and Graphene Contact. NANO LETTERS 2018; 18:1937-1945. [PMID: 29400979 DOI: 10.1021/acs.nanolett.7b05338] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A van der Waals (vdW) Schottky junction between two-dimensional (2D) transition metal dichalcogenides (TMDs) is introduced here for both vertical and in-plane current devices: Schottky diodes and metal semiconductor field-effect transistors (MESFETs). The Schottky barrier between conducting NbS2 and semiconducting n-MoS2 appeared to be as large as ∼0.5 eV due to their work-function difference. While the Schottky diode shows an ideality factor of 1.8-4.0 with an on-to-off current ratio of 103-105, Schottky-effect MESFET displays little gate hysteresis and an ideal subthreshold swing of 60-80 mV/dec due to low-density traps at the vdW interface. All MESFETs operate with a low threshold gate voltage of -0.5 ∼ -1 V, exhibiting easy saturation. It was also found that the device mobility is significantly dependent on the condition of source/drain (S/D) contact for n-channel MoS2. The highest room temperature mobility in MESFET reaches to approximately more than 800 cm2/V s with graphene S/D contact. The NbS2/n-MoS2 MESFET with graphene was successfully integrated into an organic piezoelectric touch sensor circuit with green OLED indicator, exploiting its predictable small threshold voltage, while NbS2/n-MoS2 Schottky diodes with graphene were applied to extract doping concentrations in MoS2 channel.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Taekyeong Kim
- Department of Physics , Hankuk University of Foreign Studies , 81 Oedae-ro , Chein-gu, Yongin-si 17035 , South Korea
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37
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Toft-Petersen R, Abrahamsen AB, Balog S, Porcar L, Laver M. Decomposing the Bragg glass and the peak effect in a Type-II superconductor. Nat Commun 2018; 9:901. [PMID: 29500437 PMCID: PMC5834466 DOI: 10.1038/s41467-018-03267-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 02/01/2018] [Indexed: 11/09/2022] Open
Abstract
Adding impurities or defects destroys crystalline order. Occasionally, however, extraordinary behaviour emerges that cannot be explained by perturbing the ordered state. One example is the Kondo effect, where magnetic impurities in metals drastically alter the temperature dependence of resistivity. In Type-II superconductors, disorder generally works to pin vortices, giving zero resistivity below a critical current jc. However, peaks have been observed in the temperature and field dependences of jc. This peak effect is difficult to explain in terms of an ordered Abrikosov vortex lattice. Here we test the widespread paradigm that an order-disorder transition of the vortex ensemble drives the peak effect. Using neutron scattering to probe the vortex order in superconducting vanadium, we uncover an order-disorder transition from a quasi-long-range-ordered phase to a vortex glass. The peak effect, however, is found to lie at higher fields and temperatures, in a region where thermal fluctuations of individual vortices become significant. The disordering of the vortex lattice in a type-II superconductor is widely perceived to underpin unusual peaks in the temperature and field dependence of critical current. By contrast, here Toft-Petersen et al. find an order-disorder transition in a superconducting vanadium sample that is unconnected with peaks observed in critical current.
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Affiliation(s)
- Rasmus Toft-Petersen
- Department of Physics, Technical University of Denmark (DTU), DK-2800, Kongens Lyngby, Denmark.,Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109, Berlin, Germany
| | - Asger B Abrahamsen
- Department of Wind Energy, Technical University of Denmark (DTU), DK-4000, Roskilde, Denmark
| | - Sandor Balog
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700, Fribourg, Switzerland
| | - Lionel Porcar
- Institut Laue-Langevin, 6 rue Jules Horowitz, 38042, Grenoble Cedex 9, France
| | - Mark Laver
- School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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38
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Chi Z, Chen X, Yen F, Peng F, Zhou Y, Zhu J, Zhang Y, Liu X, Lin C, Chu S, Li Y, Zhao J, Kagayama T, Ma Y, Yang Z. Superconductivity in Pristine 2H_{a}-MoS_{2} at Ultrahigh Pressure. PHYSICAL REVIEW LETTERS 2018; 120:037002. [PMID: 29400497 DOI: 10.1103/physrevlett.120.037002] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Indexed: 06/07/2023]
Abstract
As a follow-up of our previous work on pressure-induced metallization of the 2H_{c}-MoS_{2} [Chi et al., Phys. Rev. Lett. 113, 036802 (2014)PRLTAO0031-900710.1103/PhysRevLett.113.036802], here we extend pressure beyond the megabar range to seek after superconductivity via electrical transport measurements. We found that superconductivity emerges in the 2H_{a}-MoS_{2} with an onset critical temperature T_{c} of ca. 3 K at ca. 90 GPa. Upon further increasing the pressure, T_{c} is rapidly enhanced beyond 10 K and stabilized at ca. 12 K over a wide pressure range up to 220 GPa. Synchrotron x-ray diffraction measurements evidenced no further structural phase transition, decomposition, and amorphization up to 155 GPa, implying an intrinsic superconductivity in the 2H_{a}-MoS_{2}. DFT calculations suggest that the emergence of pressure-induced superconductivity is intimately linked to the emergence of a new flat Fermi pocket in the electronic structure. Our finding represents an alternative strategy for achieving superconductivity in 2H-MoS_{2} in addition to chemical intercalation and electrostatic gating.
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Affiliation(s)
- Zhenhua Chi
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Xuliang Chen
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Fei Yen
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Feng Peng
- College of Physics and Electronic Information, Luoyang Normal University, Luoyang 471022, People's Republic of China
| | - Yonghui Zhou
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Jinlong Zhu
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing 100094, People's Republic of China
| | - Yijin Zhang
- Max Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Xiaodi Liu
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Chuanlong Lin
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China
| | - Shengqi Chu
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yanchun Li
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jinggeng Zhao
- Department of Physics, Harbin Institute of Technology, Harbin 150080, People's Republic of China
- Natural Science Research Center, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080, People's Republic of China
| | - Tomoko Kagayama
- KYOKUGEN, Center for Science and Technology under Extreme Conditions, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Yanming Ma
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, People's Republic of China
| | - Zhaorong Yang
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
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39
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Berthod C, Maggio-Aprile I, Bruér J, Erb A, Renner C. Observation of Caroli-de Gennes-Matricon Vortex States in YBa_{2}Cu_{3}O_{7-δ}. PHYSICAL REVIEW LETTERS 2017; 119:237001. [PMID: 29286696 DOI: 10.1103/physrevlett.119.237001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Indexed: 06/07/2023]
Abstract
The copper oxides present the highest superconducting temperature and properties at odds with other compounds, suggestive of a fundamentally different superconductivity. In particular, the Abrikosov vortices fail to exhibit localized states expected and observed in all clean superconductors. We have explored the possibility that the elusive vortex-core signatures are actually present but weak. Combining local tunneling measurements with large-scale theoretical modeling, we positively identify the vortex states in YBa_{2}Cu_{3}O_{7-δ}. We explain their spectrum and the observed variations thereof from one vortex to the next by considering the effects of nearby vortices and disorder in the vortex lattice. We argue that the superconductivity of copper oxides is conventional, but the spectroscopic signature does not look so because the superconducting carriers are a minority.
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Affiliation(s)
- Christophe Berthod
- Department of Quantum Matter Physics, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - Ivan Maggio-Aprile
- Department of Quantum Matter Physics, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - Jens Bruér
- Department of Quantum Matter Physics, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - Andreas Erb
- Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner-Strasse 8, D-85748 Garching, Germany
| | - Christoph Renner
- Department of Quantum Matter Physics, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva, Switzerland
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40
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Heil C, Poncé S, Lambert H, Schlipf M, Margine ER, Giustino F. Origin of Superconductivity and Latent Charge Density Wave in NbS_{2}. PHYSICAL REVIEW LETTERS 2017; 119:087003. [PMID: 28952767 DOI: 10.1103/physrevlett.119.087003] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Indexed: 06/07/2023]
Abstract
We elucidate the origin of the phonon-mediated superconductivity in 2H-NbS_{2} using the ab initio anisotropic Migdal-Eliashberg theory including Coulomb interactions. We demonstrate that superconductivity is associated with Fermi surface hot spots exhibiting an unusually strong electron-phonon interaction. The electron-lattice coupling is dominated by low-energy anharmonic phonons, which place the system on the verge of a charge density wave instability. We also provide definitive evidence for two-gap superconductivity in 2H-NbS_{2}, and show that the low- and high-energy peaks observed in tunneling spectra correspond to the Γ- and K-centered Fermi surface pockets, respectively. The present findings call for further efforts to determine whether our proposed mechanism underpins superconductivity in the whole family of metallic transition metal dichalcogenides.
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Affiliation(s)
- Christoph Heil
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Samuel Poncé
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Henry Lambert
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Martin Schlipf
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Elena R Margine
- Department of Physics, Applied Physics and Astronomy, Binghamton University-SUNY, Binghamton, New York 13902, USA
| | - Feliciano Giustino
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
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41
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Sofer Z, Sedmidubský D, Luxa J, Bouša D, Huber Š, Lazar P, Veselý M, Pumera M. Universal Method for Large-Scale Synthesis of Layered Transition Metal Dichalcogenides. Chemistry 2017; 23:10177-10186. [DOI: 10.1002/chem.201701628] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Indexed: 12/29/2022]
Affiliation(s)
- Zdeněk Sofer
- Department of Inorganic Chemistry; University of Chemistry and Technology Prague; Technická 5 166 28 Prague 6 Czech Republic
| | - David Sedmidubský
- Department of Inorganic Chemistry; University of Chemistry and Technology Prague; Technická 5 166 28 Prague 6 Czech Republic
| | - Jan Luxa
- Department of Inorganic Chemistry; University of Chemistry and Technology Prague; Technická 5 166 28 Prague 6 Czech Republic
| | - Daniel Bouša
- Department of Inorganic Chemistry; University of Chemistry and Technology Prague; Technická 5 166 28 Prague 6 Czech Republic
| | - Štěpán Huber
- Department of Inorganic Chemistry; University of Chemistry and Technology Prague; Technická 5 166 28 Prague 6 Czech Republic
| | - Petr Lazar
- Regional Centre of Advanced Technologies and Materials; Department of Physical Chemistry; Faculty of Science; Palacký University Olomouc; tř. 17. listopadu 12 771 46 Olomouc Czech Republic
| | - Martin Veselý
- Department of Organic Technology; University of Chemistry and Technology Prague; Technická 5 166 28 Prague 6 Czech Republic
| | - Martin Pumera
- Division of Chemistry & Biological Chemistry; School of Physical and Mathematical Sciences; Nanyang Technological University; Singapore 637371 Singapore
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42
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Dadsetani M, Nouri T, Nejatipour H. Ab initio study of the energy loss near sulfur K and L 2,3 edges of layered MS 2 (M = Ta, Nb and V) in trigonal prismatic and octahedral structures. Micron 2017; 98:1-11. [DOI: 10.1016/j.micron.2017.03.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 03/11/2017] [Accepted: 03/11/2017] [Indexed: 12/29/2022]
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43
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Xi X, Berger H, Forró L, Shan J, Mak KF. Gate Tuning of Electronic Phase Transitions in Two-Dimensional NbSe_{2}. PHYSICAL REVIEW LETTERS 2016; 117:106801. [PMID: 27636485 DOI: 10.1103/physrevlett.117.106801] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Indexed: 06/06/2023]
Abstract
Recent experimental advances in atomically thin transition metal dichalcogenide (TMD) metals have unveiled a range of interesting phenomena including the coexistence of charge-density-wave (CDW) order and superconductivity down to the monolayer limit. The atomic thickness of two-dimensional (2D) TMD metals also opens up the possibility for control of these electronic phase transitions by electrostatic gating. Here, we demonstrate reversible tuning of superconductivity and CDW order in model 2D TMD metal NbSe_{2} by an ionic liquid gate. A variation up to ∼50% in the superconducting transition temperature has been observed. Both superconductivity and CDW order can be strengthened (weakened) by increasing (reducing) the carrier density in 2D NbSe_{2}. The doping dependence of these phase transitions can be understood as driven by a varying electron-phonon coupling strength induced by the gate-modulated carrier density and the electronic density of states near the Fermi surface.
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Affiliation(s)
- Xiaoxiang Xi
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Helmuth Berger
- Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - László Forró
- Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Jie Shan
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Kin Fai Mak
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
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44
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Timmermans M, Samuely T, Raes B, Van de Vondel J, Moshchalkov VV. Dynamic visualization of nanoscale vortex orbits. ACS NANO 2014; 8:2782-2787. [PMID: 24460428 DOI: 10.1021/nn4065007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Due to the atomic-scale resolution, scanning tunneling microscopy is an ideal technique to observe the smallest objects. Nevertheless, it suffers from very long capturing times in order to investigate dynamic processes at the nanoscale. We address this issue, for vortex matter in NbSe2, by driving the vortices using an ac magnetic field and probing the induced periodic tunnel current modulations. Our results reveal different dynamical modes of the driven vortex lattices. In addition, by recording and synchronizing the time evolution of the tunneling current at each pixel, we visualize the overall dynamics of the vortex lattice with submillisecond time resolution and subnanometer spatial resolution.
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Affiliation(s)
- Matias Timmermans
- INPAC-Institute for Nanoscale Physics and Chemistry, KU Leuven , Celestijnenlaan 200D, B-3001 Leuven, Belgium
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45
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Langer M, Kisiel M, Pawlak R, Pellegrini F, Santoro GE, Buzio R, Gerbi A, Balakrishnan G, Baratoff A, Tosatti E, Meyer E. Giant frictional dissipation peaks and charge-density-wave slips at the NbSe2 surface. NATURE MATERIALS 2014; 13:173-177. [PMID: 24336340 DOI: 10.1038/nmat3836] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 11/12/2013] [Indexed: 06/03/2023]
Abstract
Understanding nanoscale friction and dissipation is central to nanotechnology. The recent detection of the electronic-friction drop caused by the onset of superconductivity in Nb by means of an ultrasensitive non-contact pendulum atomic force microscope (AFM) raised hopes that a wider variety of mechanical-dissipation mechanisms become accessible. Here, we report a multiplet of AFM dissipation peaks arising a few nanometres above the surface of NbSe2--a layered compound exhibiting an incommensurate charge-density wave (CDW). Each peak appears at a well-defined tip-surface interaction force of the order of a nanonewton, and persists up to 70 K, where the short-range order of CDWs is known to disappear. Comparison of the measurements with a theoretical model suggests that the peaks are associated with local, tip-induced 2π phase slips of the CDW, and that dissipation maxima arise from hysteretic behaviour of the CDW phase as the tip oscillates at specific distances where sharp local slips occur.
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Affiliation(s)
- Markus Langer
- Department of Physics, University of Basel, Klingelbergstraße 82, Basel 4056, Switzerland
| | - Marcin Kisiel
- Department of Physics, University of Basel, Klingelbergstraße 82, Basel 4056, Switzerland
| | - Rémy Pawlak
- Department of Physics, University of Basel, Klingelbergstraße 82, Basel 4056, Switzerland
| | - Franco Pellegrini
- 1] SISSA, Via Bonomea 265, Trieste 34136, Italy [2] CNR-IOM Democritos National Simulation Center, Via Bonomea 265, Trieste I-34136, Italy
| | - Giuseppe E Santoro
- 1] SISSA, Via Bonomea 265, Trieste 34136, Italy [2] CNR-IOM Democritos National Simulation Center, Via Bonomea 265, Trieste I-34136, Italy [3] International Centre for Theoretical Physics (ICTP), PO Box 586, Trieste I-34014, Italy
| | - Renato Buzio
- CNR-SPIN Institute for Superconductivity, Innovative Materials and Devices, C.so Perrone 24, Genova 16152, Italy
| | - Andrea Gerbi
- CNR-SPIN Institute for Superconductivity, Innovative Materials and Devices, C.so Perrone 24, Genova 16152, Italy
| | | | - Alexis Baratoff
- Department of Physics, University of Basel, Klingelbergstraße 82, Basel 4056, Switzerland
| | - Erio Tosatti
- 1] SISSA, Via Bonomea 265, Trieste 34136, Italy [2] CNR-IOM Democritos National Simulation Center, Via Bonomea 265, Trieste I-34136, Italy [3] International Centre for Theoretical Physics (ICTP), PO Box 586, Trieste I-34014, Italy
| | - Ernst Meyer
- Department of Physics, University of Basel, Klingelbergstraße 82, Basel 4056, Switzerland
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46
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Silaev MA, Silaeva VA. Self-consistent electronic structure of multiquantum vortices in superconductors at T ≪ Tc. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:225702. [PMID: 23673423 DOI: 10.1088/0953-8984/25/22/225702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We investigate the multiquantum vortex states in a type-II superconductor in both 'clean' and 'dirty' regimes defined by impurity scattering rate. Within a quasiclassical approach we calculate self-consistently the order parameter distributions and electronic local density of states (LDOS) profiles. In the clean case we find the low temperature vortex core anomaly predicted analytically by Volovik (1993 JETP Lett. 58 455) and obtain the patterns of LDOS distributions. In the dirty regime multiquantum vortices feature a peculiar plateau in the zero energy LDOS profile, which can be considered as an experimental hallmark of multiquantum vortex formation in mesoscopic superconductors.
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Affiliation(s)
- M A Silaev
- Institute for Physics of Microstructures, Russian Academy of Sciences, N Novgorod, 603950, Russia
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47
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Assig M, Etzkorn M, Enders A, Stiepany W, Ast CR, Kern K. A 10 mK scanning tunneling microscope operating in ultra high vacuum and high magnetic fields. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:033903. [PMID: 23556826 DOI: 10.1063/1.4793793] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present design and performance of a scanning tunneling microscope (STM) that operates at temperatures down to 10 mK providing ultimate energy resolution on the atomic scale. The STM is attached to a dilution refrigerator with direct access to an ultra high vacuum chamber allowing in situ sample preparation. High magnetic fields of up to 14 T perpendicular and up to 0.5 T parallel to the sample surface can be applied. Temperature sensors mounted directly at the tip and sample position verified the base temperature within a small error margin. Using a superconducting Al tip and a metallic Cu(111) sample, we determined an effective temperature of 38 ± 1 mK from the thermal broadening observed in the tunneling spectra. This results in an upper limit for the energy resolution of ΔE = 3.5 kBT = 11.4 ± 0.3 μeV. The stability between tip and sample is 4 pm at a temperature of 15 mK as demonstrated by topography measurements on a Cu(111) surface.
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Affiliation(s)
- Maximilian Assig
- Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart, Germany
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48
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Kopnin NB, Khaymovich IM, Mel'nikov AS. Predicted multiple cores of a magnetic vortex threading a two-dimensional metal proximity coupled to a superconductor. PHYSICAL REVIEW LETTERS 2013; 110:027003. [PMID: 23383934 DOI: 10.1103/physrevlett.110.027003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Indexed: 06/01/2023]
Abstract
The structure of a proximity induced vortex core in a two-dimensional metallic layer covering a superconducting half-space is calculated. We predict the formation of a multiple vortex core characterized by two-scale behavior of the local density of states. For coherent tunneling between the two-dimensional layer and the bulk superconductor, the spectrum has two subgap branches while for incoherent tunneling only one of them remains. The resulting splitting of the zero-bias anomaly and the multiple peak structure in the local density of states should be visible in the tunneling spectroscopy experiments.
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Affiliation(s)
- N B Kopnin
- O. V. Lounasmaa Laboratory, Aalto University, P.O. Box 15100, 00076 Aalto, Finland
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49
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Singh UR, Enayat M, White SC, Wahl P. Construction and performance of a dilution-refrigerator based spectroscopic-imaging scanning tunneling microscope. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:013708. [PMID: 23387660 DOI: 10.1063/1.4788941] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report on the set-up and performance of a dilution-refrigerator based spectroscopic imaging scanning tunneling microscope. It operates at temperatures below 10 mK and in magnetic fields up to 14T. The system allows for sample transfer and in situ cleavage. We present first-results demonstrating atomic resolution and the multi-gap structure of the superconducting gap of NbSe(2) at base temperature. To determine the energy resolution of our system we have measured a normal metal/vacuum/superconductor tunneling junction consisting of an aluminum tip on a gold sample. Our system allows for continuous measurements at base temperature on time scales of up to ≈170 h.
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Affiliation(s)
- U R Singh
- Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany
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50
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Marz M, Goll G, Löhneysen HV. A scanning tunneling microscope for a dilution refrigerator. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:045102. [PMID: 20441363 DOI: 10.1063/1.3328059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We present the main features of a home-built scanning tunneling microscope that has been attached to the mixing chamber of a dilution refrigerator. It allows scanning tunneling microscopy and spectroscopy measurements down to the base temperature of the cryostat, T approximately 30 mK, and in applied magnetic fields up to 13 T. The topography of both highly ordered pyrolytic graphite and the dichalcogenide superconductor NbSe(2) has been imaged with atomic resolution down to T approximately 50 mK as determined from a resistance thermometer adjacent to the sample. As a test for a successful operation in magnetic fields, the flux-line lattice of superconducting NbSe(2) in low magnetic fields has been studied. The lattice constant of the Abrikosov lattice shows the expected field dependence proportional to 1/square root of B and measurements in the scanning tunneling spectroscopy mode clearly show the superconductive density of states with Andreev bound states in the vortex core.
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Affiliation(s)
- M Marz
- Physikalisches Institut, Karlsruher Institut für Technologie, 76131 Karlsruhe, Germany.
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