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Kumar P, Singh G, Guan X, Roy S, Lee J, Kim IY, Li X, Bu F, Bahadur R, Iyengar SA, Yi J, Zhao D, Ajayan PM, Vinu A. The Rise of Xene Hybrids. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2403881. [PMID: 38899836 DOI: 10.1002/adma.202403881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 05/22/2024] [Indexed: 06/21/2024]
Abstract
Xenes, mono-elemental atomic sheets, exhibit Dirac/Dirac-like quantum behavior. When interfaced with other 2D materials such as boron nitride, transition metal dichalcogenides, and metal carbides/nitrides/carbonitrides, it enables them with unique physicochemical properties, including structural stability, desirable bandgap, efficient charge carrier injection, flexibility/breaking stress, thermal conductivity, chemical reactivity, catalytic efficiency, molecular adsorption, and wettability. For example, BN acts as an anti-oxidative shield, MoS2 injects electrons upon laser excitation, and MXene provides mechanical flexibility. Beyond precise compositional modulations, stacking sequences, and inter-layer coupling controlled by parameters, achieving scalability and reproducibility in hybridization is crucial for implementing these quantum materials in consumer applications. However, realizing the full potential of these hybrid materials faces challenges such as air gaps, uneven interfaces, and the formation of defects and functional groups. Advanced synthesis techniques, a deep understanding of quantum behaviors, precise control over interfacial interactions, and awareness of cross-correlations among these factors are essential. Xene-based hybrids show immense promise for groundbreaking applications in quantum computing, flexible electronics, energy storage, and catalysis. In this timely perspective, recent discoveries of novel Xenes and their hybrids are highlighted, emphasizing correlations among synthetic parameters, structure, properties, and applications. It is anticipated that these insights will revolutionize diverse industries and technologies.
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Affiliation(s)
- Prashant Kumar
- Global Innovative Centre for Advanced Nanomaterials (GICAN), College of Engineering, Science and Environment (CESE), University of Newcastle, University Drive, Callaghan, New South Wales, 2308, Australia
| | - Gurwinder Singh
- Global Innovative Centre for Advanced Nanomaterials (GICAN), College of Engineering, Science and Environment (CESE), University of Newcastle, University Drive, Callaghan, New South Wales, 2308, Australia
| | - Xinwei Guan
- Global Innovative Centre for Advanced Nanomaterials (GICAN), College of Engineering, Science and Environment (CESE), University of Newcastle, University Drive, Callaghan, New South Wales, 2308, Australia
| | - Soumyabrata Roy
- Department of Materials Science and Nano Engineering, Rice University, 6100 Main St, Houston, TX, 77005, USA
- Department of Sustainable Energy Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India
| | - Jangmee Lee
- Global Innovative Centre for Advanced Nanomaterials (GICAN), College of Engineering, Science and Environment (CESE), University of Newcastle, University Drive, Callaghan, New South Wales, 2308, Australia
| | - In Young Kim
- Global Innovative Centre for Advanced Nanomaterials (GICAN), College of Engineering, Science and Environment (CESE), University of Newcastle, University Drive, Callaghan, New South Wales, 2308, Australia
| | - Xiaomin Li
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, State Key Laboratory of Molecular Engineering of Polymers, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Fudan University, Shanghai, 200433, P. R. China
| | - Fanxing Bu
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, State Key Laboratory of Molecular Engineering of Polymers, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Fudan University, Shanghai, 200433, P. R. China
| | - Rohan Bahadur
- Global Innovative Centre for Advanced Nanomaterials (GICAN), College of Engineering, Science and Environment (CESE), University of Newcastle, University Drive, Callaghan, New South Wales, 2308, Australia
| | - Sathvik Ajay Iyengar
- Department of Materials Science and Nano Engineering, Rice University, 6100 Main St, Houston, TX, 77005, USA
| | - Jiabao Yi
- Global Innovative Centre for Advanced Nanomaterials (GICAN), College of Engineering, Science and Environment (CESE), University of Newcastle, University Drive, Callaghan, New South Wales, 2308, Australia
| | - Dongyuan Zhao
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, State Key Laboratory of Molecular Engineering of Polymers, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Fudan University, Shanghai, 200433, P. R. China
| | - Pulickel M Ajayan
- Department of Materials Science and Nano Engineering, Rice University, 6100 Main St, Houston, TX, 77005, USA
| | - Ajayan Vinu
- Global Innovative Centre for Advanced Nanomaterials (GICAN), College of Engineering, Science and Environment (CESE), University of Newcastle, University Drive, Callaghan, New South Wales, 2308, Australia
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Ichinokura S, Tokuda K, Toyoda M, Tanaka K, Saito S, Hirahara T. Van Hove Singularity and Enhanced Superconductivity in Ca-Intercalated Bilayer Graphene Induced by Confinement Epitaxy. ACS NANO 2024; 18:13738-13744. [PMID: 38741024 DOI: 10.1021/acsnano.4c01757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
We demonstrate the impact of high-density calcium introduction into Ca-intercalated bilayer graphene on a SiC substrate, wherein a metallic layer of Ca has been identified at the interface. We have discerned that the additional Ca layer engenders a free-electron-like band, which subsequently hybridizes with a Dirac band, leading to the emergence of a van Hove singularity. Coinciding with this, there is an increase in the critical temperature for superconductivity. These findings allude to the manifestation of Ca-driven confinement epitaxy, augmenting superconductivity through the enhancement of attractive interactions in a pair of electron and hole bands with flat dispersion around the Fermi level.
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Affiliation(s)
- Satoru Ichinokura
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Kei Tokuda
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Masayuki Toyoda
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Kiyohisa Tanaka
- UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
| | - Susumu Saito
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Toru Hirahara
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
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3
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Tan JH, Wang H, Chen YJ, Jiao N, Zheng MM, Lu HY, Zhang P. Superconductivity in Ca-intercalated bilayer graphene: C 2CaC 2. Phys Chem Chem Phys 2024; 26:11429-11435. [PMID: 38563510 DOI: 10.1039/d3cp06245g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The deposition and intercalation of metal atoms can induce superconductivity in monolayer and bilayer graphenes. For example, it has been experimentally proved that Li-deposited graphene is a superconductor with critical temperature Tc of 5.9 K, Ca-intercalated bilayer graphene C6CaC6 and K-intercalated epitaxial bilayer graphene C8KC8 are superconductors with Tc of 2-4 K and 3.6 K, respectively. However, the Tc of them are relatively low. To obtain higher Tc in graphene-based superconductors, here we predict a new Ca-intercalated bilayer graphene C2CaC2, which shows higher Ca concentration than the C6CaC6. It is proved to be thermodynamically and dynamically stable. The electronic structure, electron-phonon coupling (EPC) and superconductivity of C2CaC2 are investigated based on first-principles calculations. The EPC of C2CaC2 mainly comes from the coupling between the electrons of C-pz orbital and the high- and low-frequency vibration modes of C atoms. The calculated EPC constant λ of C2CaC2 is 0.75, and the superconducting Tc is 18.9 K, which is much higher than other metal-intercalated bilayer graphenes. By further applying -4% biaxial compressive strain to C2CaC2, the Tc can be boosted to 26.6 K. Thus, the predicted C2CaC2 provides a new platform for realizing superconductivity with the highest Tc in bilayer graphenes.
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Affiliation(s)
- Jin-Han Tan
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Hao Wang
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Ying-Jie Chen
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Na Jiao
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Meng-Meng Zheng
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Hong-Yan Lu
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Ping Zhang
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
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4
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Aygar AM, Durnan O, Molavi B, Bovey SNR, Grüneis A, Szkopek T. Mass Inversion at the Lifshitz Transition in Monolayer Graphene by Diffusive, High-Density, On-Chip Doping. ACS NANO 2024; 18:9092-9099. [PMID: 38479375 DOI: 10.1021/acsnano.3c13187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
Experimental setups for charge transport measurements are typically not compatible with the ultrahigh vacuum conditions for chemical doping, limiting the charge carrier density that can be investigated by transport methods. Field-effect methods, including dielectric gating and ionic liquid gating, achieve too low a carrier density to induce electronic phase transitions. To bridge this gap, we developed an integrated flip-chip method to dope graphene by alkali vapor in the diffusive regime, suitable for charge transport measurements at ultrahigh charge carrier density. We introduce a cesium droplet into a sealed cavity filled with inert gas to dope a monolayer graphene sample by the process of cesium atom diffusion, adsorption, and ionization at the graphene surface, with doping beyond an electron density of 4.7 × 1014 cm-2 monitored by operando Hall measurement. The sealed assembly is stable against oxidation, enabling measurement of charge transport versus temperature and magnetic field. Cyclotron mass inversion is observed via the Hall effect, indicative of the change in Fermi surface geometry associated with the Liftshitz transition at the hyperbolic M point of monolayer graphene. The transparent quartz substrate also functions as an optical window, enabling nonresonant Raman scattering. Our findings show that chemical doping, hitherto restricted to ultrahigh vacuum, can be applied in a diffusive regime at ambient pressure in an inert gas environment and thus enable charge transport studies in standard cryogenic environments.
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Affiliation(s)
- Ayse Melis Aygar
- Department of Electrical and Computer Engineering, McGill University, Québec, Montréal H3A-0E9, Canada
| | - Oliver Durnan
- Department of Electrical Engineering, Columbia University, New York, New York 10027, United States
| | - Bahar Molavi
- Department of Electrical and Computer Engineering, McGill University, Québec, Montréal H3A-0E9, Canada
| | - Sam N R Bovey
- Department of Electrical and Computer Engineering, McGill University, Québec, Montréal H3A-0E9, Canada
| | - Alexander Grüneis
- Institut für Festkörperelektronik, Technische Universität Wien, Vienna 1040, Austria
| | - Thomas Szkopek
- Department of Electrical and Computer Engineering, McGill University, Québec, Montréal H3A-0E9, Canada
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5
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Dufresne SKY, Zhdanovich S, Michiardi M, Guislain BG, Zonno M, Mazzotti V, O'Brien L, Kung S, Levy G, Mills AK, Boschini F, Jones DJ, Damascelli A. A versatile laser-based apparatus for time-resolved ARPES with micro-scale spatial resolution. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:033907. [PMID: 38517258 DOI: 10.1063/5.0176170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 02/28/2024] [Indexed: 03/23/2024]
Abstract
We present the development of a versatile apparatus for 6.2 eV laser-based time and angle-resolved photoemission spectroscopy with micrometer spatial resolution (time-resolved μ-ARPES). With a combination of tunable spatial resolution down to ∼11 μm, high energy resolution (∼11 meV), near-transform-limited temporal resolution (∼280 fs), and tunable 1.55 eV pump fluence up to 3 mJ/cm2, this time-resolved μ-ARPES system enables the measurement of ultrafast electron dynamics in exfoliated and inhomogeneous materials. We demonstrate the performance of our system by correlating the spectral broadening of the topological surface state of Bi2Se3 with the spatial dimension of the probe pulse, as well as resolving the spatial inhomogeneity contribution to the observed spectral broadening. Finally, after in situ exfoliation, we performed time-resolved μ-ARPES on a ∼30 μm flake of transition metal dichalcogenide WTe2, thus demonstrating the ability to access ultrafast electron dynamics with momentum resolution on micro-exfoliated materials.
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Affiliation(s)
- S K Y Dufresne
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - S Zhdanovich
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - M Michiardi
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - B G Guislain
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - M Zonno
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - V Mazzotti
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - L O'Brien
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - S Kung
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - G Levy
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - A K Mills
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - F Boschini
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Centre Énergie Matériaux Télécommunications, Institut National de la Recherche Scientifique, Varennes, Québec J3X 1S2, Canada
| | - D J Jones
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - A Damascelli
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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6
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Huang W, Seo JA, Canavan MP, Gambardella P, Stepanow S. Observation of different Li intercalation states and local doping in epitaxial mono- and bilayer graphene on SiC(0001). NANOSCALE 2024; 16:3160-3165. [PMID: 38259148 PMCID: PMC10851339 DOI: 10.1039/d3nr03070a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 01/10/2024] [Indexed: 01/24/2024]
Abstract
Li intercalation is commonly used to enhance the carrier density in epitaxial graphene and mitigate coupling to the substrate. So far, the understanding of the intercalation process, particularly how Li penetrates different layers above the substrate, and its impact on electron transport remains incomplete. Here, we report different phases of Li intercalation and their kinetic processes in epitaxial mono- and bilayer graphene grown on SiC. The distinct doping effects of each intercalation phase are characterized using scanning tunneling spectroscopy. Furthermore, changes in the local conduction regimes are directly mapped by scanning tunneling potentiometry and attributed to different charge transfer states of the intercalated Li. The stable intercalation marked by the formation of Li-Si bonds leads to a significant 56% reduction in sheet resistance of the resulting quasi-free bilayer graphene, as compared to the pristine monolayer graphene.
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Affiliation(s)
- Wei Huang
- Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
| | - Jeong Ah Seo
- Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
| | - Mark P Canavan
- Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
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7
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Hai Y, Jiang M, Tian H, Zhong G, Li W, Yang C, Chen X, Lin H. Superconductivity Above 100 K Predicted in Carbon-Cage Network. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2303639. [PMID: 37807820 PMCID: PMC10667821 DOI: 10.1002/advs.202303639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 08/22/2023] [Indexed: 10/10/2023]
Abstract
To explore carbide superconductors with higher transition temperature, two novel carbon structures of cage-network are designed and their superconductivity is studied by doping metals. MC6 and MC10 are respectively identified as C24 and C32 cage-network structures. This study finds that both carbon structures drive strong electron-phonon interaction and can exhibit superconductivity above liquid nitrogen temperature. Importantly, the superconducting transition temperatures above 100 K are predicted to be achieved in C24 -cage-network systems doped by Na, Mg, Al, In, and Tl at ambient pressure, which is far higher than those in graphite, fullerene, and other carbides. Meanwhile, the superconductivity of cage-network carbides is also found to be sensitive to the electronegativity and concentration of dopant M. The result indicates that the higher transition temperatures can be obtained by optimizing the carbon-cage-network structures and the doping conditions. The study suggests that the carbon-cage-network structure is a direction to explore high-temperature superconducting carbides.
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Affiliation(s)
- Yu‐Long Hai
- Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen518055China
- Nano Science and Technology InstituteUniversity of Science and Technology of ChinaSuzhou215123China
| | - Meng‐Jing Jiang
- Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen518055China
- Nano Science and Technology InstituteUniversity of Science and Technology of ChinaSuzhou215123China
| | - Hui‐Li Tian
- Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen518055China
- Nano Science and Technology InstituteUniversity of Science and Technology of ChinaSuzhou215123China
| | - Guo‐Hua Zhong
- Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen518055China
- University of Chinese Academy of SciencesBeijing100049China
| | - Wen‐Jie Li
- Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen518055China
- University of Chinese Academy of SciencesBeijing100049China
| | - Chun‐Lei Yang
- Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen518055China
- University of Chinese Academy of SciencesBeijing100049China
| | - Xiao‐Jia Chen
- School of ScienceHarbin Institute of TechnologyShenzhen518055China
- Center for High Pressure Science and Technology Advanced ResearchShanghai201203China
| | - Hai‐Qing Lin
- School of PhysicsZhejiang UniversityHangzhou310058China
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8
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Cheng Y, Li Z, Liu Y, Shi Y, Zhu M. Advances in the synthesis and modification of two-dimensional antimonene. Phys Chem Chem Phys 2023; 25:21773-21786. [PMID: 37577758 DOI: 10.1039/d3cp00892d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Antimonene with a honeycomb layered structure has great application prospects in a wide spectrum of domains due to its high carrier mobility, high thermal conductivity, and layer-dependent electrical properties. Since the first successful synthesis of antimonene by epitaxy in 2015, various fabrication methods have been proposed successively. Herein, several representative synthetic methods are described in detail, including mechanical exfoliation, epitaxial growth, liquid-phase exfoliation, electrochemical exfoliation, etc. In addition, band engineering via modification strategies of antimonene, particularly intercalation and doping, is discussed based on available theoretical studies. By comparing the achieved structure characteristics and performances of these different synthesis and modification strategies, we present promising future developments and critical challenges for antimonene.
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Affiliation(s)
- Yanjie Cheng
- School of Electronic Information Engineering, Hebei University of Technology, Tianjin, 300130, People's Republic of China.
- Tianjin Key Laboratory of Electronic Materials and Devices, Hebei University of Technology, Tianjin, 300130, People's Republic of China
| | - Zhe Li
- School of Electronic Information Engineering, Hebei University of Technology, Tianjin, 300130, People's Republic of China.
- Tianjin Key Laboratory of Electronic Materials and Devices, Hebei University of Technology, Tianjin, 300130, People's Republic of China
| | - Ye Liu
- School of Electronic Information Engineering, Hebei University of Technology, Tianjin, 300130, People's Republic of China.
- Tianjin Key Laboratory of Electronic Materials and Devices, Hebei University of Technology, Tianjin, 300130, People's Republic of China
| | - Yunhui Shi
- School of Electronic Information Engineering, Hebei University of Technology, Tianjin, 300130, People's Republic of China.
- Tianjin Key Laboratory of Electronic Materials and Devices, Hebei University of Technology, Tianjin, 300130, People's Republic of China
- Hebei Collaborative Innovation Center of Microelectronic Materials and Technology on Ultra Precision Processing (CIC), Tianjin, 300130, China
- Hebei Engineering Research Center of Microelectronic Materials and Devices (ERC), Tianjin, 300130, China
| | - Mengya Zhu
- School of Electronic Information Engineering, Hebei University of Technology, Tianjin, 300130, People's Republic of China.
- Tianjin Key Laboratory of Electronic Materials and Devices, Hebei University of Technology, Tianjin, 300130, People's Republic of China
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9
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Liu Q, Lu X, Liu Y, Li Z, Yan P, Chen W, Meng Q, Zhang Y, Yam C, He L, Yan Y, Zhang Y, Wu J, Frauenheim T, Zhang R, Xu Y. Carrier Relaxation and Multiplication in Bi Doped Graphene. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2206218. [PMID: 36670078 DOI: 10.1002/smll.202206218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 01/09/2023] [Indexed: 05/04/2023]
Abstract
By introducing different contents of Bi adatoms to the surface of monolayer graphene, the carrier concentration and their dynamics have been effectively modulated as probed directly by the time- and angle-resolved photoemission spectroscopy technique. The Bi adatoms are found to assist acoustic phonon scattering events mediated by supercollisions as the disorder effectively relaxes the momentum conservation constraint. A reduced carrier multiplication has been observed, which is related to the shrinking Fermi sea for scattering, as confirmed by time-dependent density functional theory simulation. This work gives insight into hot carrier dynamics in graphene, which is crucial for promoting the application of photoelectric devices.
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Affiliation(s)
- Qi Liu
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
| | - Xianyang Lu
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
| | - Yuxiang Liu
- Bremen Center for Computational Materials Science, University of Bremen, Am Fallturm 1, 28359, Bremen, Germany
| | - Zhihao Li
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
| | - Pengfei Yan
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
| | - Wang Chen
- National Laboratory of Solid State Microstructure, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Qinghao Meng
- National Laboratory of Solid State Microstructure, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Yongheng Zhang
- National Laboratory of Solid State Microstructure, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - ChiYung Yam
- Shenzhen Institute for Advanced Study, University of Electronic Science and Technology of China, Shenzhen, 518000, China
- Hong Kong Quantum AI Lab Limited, Hong Kong, 00000, China
| | - Liang He
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
| | - Yu Yan
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
| | - Yi Zhang
- National Laboratory of Solid State Microstructure, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Jing Wu
- York-Nanjing Joint Center (YNJC) for Spintronics and Nano-engineering, Department of Electronics and Physics, University of York, York, YO10 5DD, UK
| | - Thomas Frauenheim
- Bremen Center for Computational Materials Science, University of Bremen, Am Fallturm 1, 28359, Bremen, Germany
- Beijing Computational Science Research Center, Haidian District, Beijing, 100193, China
- Shenzhen JL Computational Science and Applied Research Institute, Shenzhen, 518109, China
| | - Rong Zhang
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
| | - Yongbing Xu
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
- York-Nanjing Joint Center (YNJC) for Spintronics and Nano-engineering, Department of Electronics and Physics, University of York, York, YO10 5DD, UK
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10
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Liu R, Lu J, Chen H, Zhao X, Hu G, Yuan X, Ren J. Prediction of π-electrons mediated high-temperature superconductivity in monolayer LiC 12. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:144001. [PMID: 36689775 DOI: 10.1088/1361-648x/acb582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Accepted: 01/23/2023] [Indexed: 06/17/2023]
Abstract
Prediction and synthesis of two-dimensional high transition temperature (TC) superconductors is an area of extensive research. Based on calculations of the electronic structures and lattice dynamics, we predict that graphene-like layered monolayer LiC12is aπ-electrons mediated Bardeen-Cooper-Schrieffer-type superconductor. Monolayer LiC12is theoretically stable and expected to be synthesized experimentally. From the band structures and the phonon dispersion spectrum, it is found that the saddle point ofπ-bonding bands induces large density of states at the Fermi energy level. There is strongly coupled between the vibration mode in the in-plane direction of the lithium atoms and theπ-electrons of carbon atoms, which induces the high-TCsuperconductivity in LiC12. TheTCcan reach to 41 K under an applied 10% biaxial tensile strain based on the anisotropic Eliashberg equation. Our results show that monolayer LiC12is a good candidate asπ-electrons mediated electron-phonon coupling high-TCsuperconductor.
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Affiliation(s)
- Ran Liu
- School of Physics and Electronics, Shandong Normal University, Jinan 250358, People's Republic of China
| | - Jiajun Lu
- School of Physics and Electronics, Shandong Normal University, Jinan 250358, People's Republic of China
| | - Hongxin Chen
- School of Physics and Electronics, Shandong Normal University, Jinan 250358, People's Republic of China
| | - Xiuwen Zhao
- School of Physics and Electronics, Shandong Normal University, Jinan 250358, People's Republic of China
| | - Guichao Hu
- School of Physics and Electronics, Shandong Normal University, Jinan 250358, People's Republic of China
| | - Xiaobo Yuan
- School of Physics and Electronics, Shandong Normal University, Jinan 250358, People's Republic of China
| | - Junfeng Ren
- School of Physics and Electronics, Shandong Normal University, Jinan 250358, People's Republic of China
- Shandong Provincial Engineering and Technical Center of Light Manipulations & Institute of Materials and Clean Energy, Shandong Normal University, Jinan 250358, People's Republic of China
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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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Wang Y, Crespi VH, Cohen ML, Nourhani A. Nonstoichiometric Salt Intercalation as a Means to Stabilize Alkali Doping of 2D Materials. PHYSICAL REVIEW LETTERS 2022; 129:266401. [PMID: 36608189 DOI: 10.1103/physrevlett.129.266401] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 08/11/2022] [Accepted: 09/30/2022] [Indexed: 06/17/2023]
Abstract
Although doping with alkali atoms is a powerful technique for introducing charge carriers into physical systems, the resulting charge-transfer systems are generally not air stable. Here we describe computationally a strategy towards increasing the stability of alkali-doped materials that employs stoichiometrically unbalanced salt crystals with excess cations (which could be deposited during, e.g., in situ gating) to achieve doping levels similar to those attained by pure alkali metal doping. The crystalline interior of the salt crystal acts as a template to stabilize the excess dopant atoms against oxidation and deintercalation, which otherwise would be highly favorable. We characterize this doping method for graphene, NbSe_{2}, and Bi_{2}Se_{3} and its effect on direct-to-indirect band gap transitions, 2D superconductivity, and thermoelectric performance. Salt intercalation should be generally applicable to systems which can accommodate this "ionic crystal" doping (and particularly favorable when geometrical packing constraints favor nonstoichiometry).
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Affiliation(s)
- Yuanxi Wang
- 2-Dimensional Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Physics, University of North Texas, Denton, Texas 76201, USA
| | - Vincent H Crespi
- 2-Dimensional Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Marvin L Cohen
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Amir Nourhani
- Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA
- Biomimicry Research and Innovation Center, University of Akron, Akron, Ohio 44325, USA
- Departments of Biology, Mathematics, and Chemical, Biomolecular, and Corrosion Engineering, University of Akron, Akron, Ohio 44325, USA
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13
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Talantsev EF. Quantifying Nonadiabaticity in Major Families of Superconductors. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 13:71. [PMID: 36615981 PMCID: PMC9824585 DOI: 10.3390/nano13010071] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/17/2022] [Accepted: 12/19/2022] [Indexed: 06/17/2023]
Abstract
The classical Bardeen−Cooper−Schrieffer and Eliashberg theories of the electron−phonon-mediated superconductivity are based on the Migdal theorem, which is an assumption that the energy of charge carriers, kBTF, significantly exceeds the phononic energy, ℏωD, of the crystalline lattice. This assumption, which is also known as adiabatic approximation, implies that the superconductor exhibits fast charge carriers and slow phonons. This picture is valid for pure metals and metallic alloys because these superconductors exhibit ℏωDkBTF<0.01. However, for n-type-doped semiconducting SrTiO3, this adiabatic approximation is not valid, because this material exhibits ℏωDkBTF≅50. There is a growing number of newly discovered superconductors which are also beyond the adiabatic approximation. Here, leaving aside pure theoretical aspects of nonadiabatic superconductors, we classified major classes of superconductors (including, elements, A-15 and Heusler alloys, Laves phases, intermetallics, noncentrosymmetric compounds, cuprates, pnictides, highly-compressed hydrides, and two-dimensional superconductors) by the strength of nonadiabaticity (which we defined by the ratio of the Debye temperature to the Fermi temperature, TθTF). We found that the majority of analyzed superconductors fall into the 0.025≤TθTF≤0.4 band. Based on the analysis, we proposed the classification scheme for the strength of nonadiabatic effects in superconductors and discussed how this classification is linked with other known empirical taxonomies in superconductivity.
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Affiliation(s)
- Evgueni F. Talantsev
- M. N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18 S. Kovalevskoy Str., 620108 Ekaterinburg, Russia; ; Tel.: +7-912-676-0374
- NANOTECH Centre, Ural Federal University, 19 Mira Str., 620002 Ekaterinburg, Russia
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14
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Senturk AE, Akgün G. Exploring the thermal conductivity and mechanical properties of BN-doped graphyne. J Mol Model 2022; 28:383. [DOI: 10.1007/s00894-022-05379-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 11/05/2022] [Indexed: 11/13/2022]
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15
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Wang C, Wang H, Tian Q, Zong J, Xie X, Chen W, Zhang Y, Wang K, Qiu X, Wang L, Li F, Zhang H, Zhang Y. Suppression of Intervalley Coupling in Graphene via Potassium Doping. J Phys Chem Lett 2022; 13:9396-9403. [PMID: 36190902 DOI: 10.1021/acs.jpclett.2c02657] [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
The quantum interference patterns induced by impurities in graphene can form the (√3 × √3)R30° superlattice with intervalley scattering. This superlattice can lead to the folded Dirac cone at the center of Brillouin zone by coupling two non-equivalent valleys. Using angle-resolved photoemission spectroscopy (ARPES), we report the observation of suppression of the folded Dirac cone in mono- and bilayer graphene upon potassium doping. The intervalley coupling with chiral symmetry broken can persist upon a light potassium-doped level but be ruined at the heavily doped level. Meanwhile, the folded Dirac cone can be suppressed by the renormalization of the Dirac band with potassium doping. Our results demonstrate that the suppression of the intervalley scattering pattern by potassium doping could pave the way toward the realization of novel chiraltronic devices in superlattice graphene.
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Affiliation(s)
- Can Wang
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
| | - Huaiqiang Wang
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
| | - Qichao Tian
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
| | - Junyu Zong
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
| | - Xuedong Xie
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
| | - Wang Chen
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
| | - Yongheng Zhang
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
| | - Kaili Wang
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
| | - Xiaodong Qiu
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
| | - Li Wang
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou, Jiangsu 215123, People's Republic of China
| | - Fangsen Li
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou, Jiangsu 215123, People's Republic of China
| | - Haijun Zhang
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
| | - Yi Zhang
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, Jiangsu 210093, People's Republic of China
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16
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Wang X, Liu N, Wu Y, Qu Y, Zhang W, Wang J, Guan D, Wang S, Zheng H, Li Y, Liu C, Jia J. Strong Coupling Superconductivity in Ca-Intercalated Bilayer Graphene on SiC. NANO LETTERS 2022; 22:7651-7658. [PMID: 36066512 DOI: 10.1021/acs.nanolett.2c02804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The metal-intercalated bilayer graphene has a flat band with a high density of states near the Fermi energy and thus is anticipated to exhibit an enhanced strong correlation effect and associated fascinating phenomena, including superconductivity. By using a self-developed multifunctional scanning tunneling microscope, we succeeded in observing the superconducting energy gap and diamagnetic response of a Ca-intercalated bilayer graphene below a critical temperature of 8.83 K. The revealed high value of gap ratio, 2Δ/kBTc ≈ 5.0, indicates a strong coupling superconductivity, while the variation of penetration depth with temperature and magnetic field indicates an isotropic s-wave superconductor. These results provide crucial experimental clues for understanding the origin and mechanism of superconductivity in carrier-doped graphene.
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Affiliation(s)
- Xutao Wang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
| | - Ningning Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
| | - Yanfu Wu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
| | - Yueqiao Qu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
| | - Wenxuan Zhang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
| | - Jinyue Wang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
| | - Dandan Guan
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
| | - Shiyong Wang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
| | - Hao Zheng
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
| | - Yaoyi Li
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
| | - Canhua Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
- Tsung-Dao Lee Institute, Shanghai 200240, People's Republic of China
| | - Jinfeng Jia
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
- Tsung-Dao Lee Institute, Shanghai 200240, People's Republic of China
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17
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Kumar S, Pratap S, Kumar V, Mishra RK, Gwag JS, Chakraborty B. Electronic, transport, magnetic and optical properties of graphene nanoribbons review. LUMINESCENCE 2022. [PMID: 35850156 DOI: 10.1002/bio.4334] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 06/03/2022] [Accepted: 06/14/2022] [Indexed: 11/08/2022]
Abstract
Low dimensional materials have attracted great research interest from both theoretical and experimental point of view. These materials exhibit novel physical and chemical properties due to the confinement effect in low dimensions. The experimental observations of graphene open a new platform to study the physical properties of materials restricted to two dimensions. This featured article provides a review on the novel properties of quasi one-dimensional (1D) material known as graphene nanoribbon. Graphene nanoribbons can be obtained by unzipping carbon nanotubes (CNTs) or cutting the graphene sheet. Alternatively, it is also called the finite termination of graphene edges. It gives rise different edge geometries namely zigzag and armchair among others. There are various physical and chemical techniques to realize these materials. Depending on the edge type termination, these are called the zigzag and armchair graphene nanoribbons (ZGNR and AGNR). These edges play an important role in controlling the properties of graphene nanoribbons. The present review article provides an overview of the electronic, transport, optical and magnetic properties of graphene nanoribbons. However, there are different ways to tune these properties for device applications. Here, some of them are highlighted such as external perturbations and chemical modifications. Few applications of graphene nanoribbon have and chemical modifications. Few applications of graphene nanoribbon have also been briefly discussed.
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Affiliation(s)
- Sandeep Kumar
- Department of Physics and astronomical Science, Central University of Himachal Pradesh, Kangra, H.P, India
| | - Surender Pratap
- Department of Physics and astronomical Science, Central University of Himachal Pradesh, Kangra, H.P, India
| | - Vipin Kumar
- Department of Physics, Yeungnam University, Gyeongsan, South Korea
| | | | - Jin Seog Gwag
- Department of Physics, Yeungnam University, Gyeongsan, South Korea
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18
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Qu AC, Nigge P, Link S, Levy G, Michiardi M, Spandar PL, Matthé T, Schneider M, Zhdanovich S, Starke U, Gutiérrez C, Damascelli A. Ubiquitous defect-induced density wave instability in monolayer graphene. SCIENCE ADVANCES 2022; 8:eabm5180. [PMID: 35675409 PMCID: PMC9177069 DOI: 10.1126/sciadv.abm5180] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 04/20/2022] [Indexed: 06/15/2023]
Abstract
Quantum materials are notoriously sensitive to their environments, where small perturbations can tip a system toward one of several competing ground states. Graphene hosts a rich assortment of such competing phases, including a bond density wave instability ("Kekulé distortion") that couples electrons at the K/K' valleys and breaks the lattice symmetry. Here, we report observations of a ubiquitous Kekulé distortion across multiple graphene systems. We show that extremely dilute concentrations of surface atoms (less than three adsorbed atoms every 1000 graphene unit cells) can self-assemble and trigger the onset of a global Kekulé density wave phase. Combining complementary momentum-sensitive angle-resolved photoemission spectroscopy (ARPES) and low-energy electron diffraction (LEED) measurements, we confirm the presence of this density wave phase and observe the opening of an energy gap. Our results reveal an unexpected sensitivity of the graphene lattice to dilute surface disorder and show that adsorbed atoms offer an attractive route toward designing novel phases in two-dimensional materials.
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Affiliation(s)
- A. C. Qu
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, Canada
| | - P. Nigge
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, Canada
| | - S. Link
- Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - G. Levy
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, Canada
| | - M. Michiardi
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, Canada
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | - P. L. Spandar
- Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA, USA
| | - T. Matthé
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, Canada
| | - M. Schneider
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, Canada
| | - S. Zhdanovich
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, Canada
| | - U. Starke
- Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - C. Gutiérrez
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, Canada
- Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA, USA
| | - A. Damascelli
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, Canada
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19
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Kovarik S, Robles R, Schlitz R, Seifert TS, Lorente N, Gambardella P, Stepanow S. Electron Paramagnetic Resonance of Alkali Metal Atoms and Dimers on Ultrathin MgO. NANO LETTERS 2022; 22:4176-4181. [PMID: 35512394 DOI: 10.1021/acs.nanolett.2c00980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Electron paramagnetic resonance (EPR) can provide unique insight into the chemical structure and magnetic properties of dopants in oxide and semiconducting materials that are of interest for applications in electronics, catalysis, and quantum sensing. Here, we demonstrate that EPR in combination with scanning tunneling microscopy (STM) allows for probing the bonding and charge state of alkali metal atoms on an ultrathin magnesium oxide layer on a Ag substrate. We observe a magnetic moment of 1 μB for Li2, LiNa, and Na2 dimers corresponding to spin radicals with a charge state of +1e. Single alkali atoms have the same charge state and no magnetic moment. The ionization of the adsorbates is attributed to charge transfer through the oxide to the metal substrate. Our work highlights the potential of EPR-STM to provide insight into dopant atoms that are relevant for the control of the electrical properties of surfaces and nanodevices.
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Affiliation(s)
- Stepan Kovarik
- Department of Materials, ETH Zurich, Hönggerbergring 64, Zürich CH-8093, Switzerland
| | - Roberto Robles
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, San Sebastián 20018, Spain
| | - Richard Schlitz
- Department of Materials, ETH Zurich, Hönggerbergring 64, Zürich CH-8093, Switzerland
| | - Tom Sebastian Seifert
- Department of Materials, ETH Zurich, Hönggerbergring 64, Zürich CH-8093, Switzerland
- Department of Physics, Freie Universität Berlin, Berlin 14195, Germany
| | - Nicolas Lorente
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, San Sebastián 20018, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, San Sebastián 20018, Spain
| | - Pietro Gambardella
- Department of Materials, ETH Zurich, Hönggerbergring 64, Zürich CH-8093, Switzerland
| | - Sebastian Stepanow
- Department of Materials, ETH Zurich, Hönggerbergring 64, Zürich CH-8093, Switzerland
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20
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Li YP, Yang L, Liu HD, Jiao N, Ni MY, Hao N, Lu HY, Zhang P. Phonon-mediated superconductivity in two-dimensional hydrogenated phosphorus carbide: HPC 3. Phys Chem Chem Phys 2022; 24:9256-9262. [PMID: 35388845 DOI: 10.1039/d2cp00997h] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In recent years, three-dimensional (3D) high-temperature superconductors at ultrahigh pressure have been reported, typical examples are the polyhydrides H3S, LaH10, YH9, etc. To find high-temperature two-dimensional (2D) superconductors at atmospheric pressure is another research hotspot. Here, we investigated the possible superconductivity in a hydrogenated monolayer phosphorus carbide based on first-principles calculations. The results reveal that monolayer PC3 transforms from a semiconductor to a metal after hydrogenation. Interestingly, the C-π-bonding band contributes most to the states at the Fermi level. Based on the electron-phonon coupling mechanism, it is found that the electron-phonon coupling constant of HPC3 is 0.95, which mainly originates from the coupling of C-π electrons with the in-plane vibration modes of C and H. The calculated critical temperature Tc is 31.0 K, which is higher than those in most 2D superconductors. By further applying a biaxial tensile strain of 3%, the Tc can be boosted to 57.3 K, exceeding the McMillan limit. Thus, hydrogenation and strain are effective ways for increasing the superconducting Tc of 2D materials.
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Affiliation(s)
- Ya-Ping Li
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Liu Yang
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Hao-Dong Liu
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Na Jiao
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Mei-Yan Ni
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Ning Hao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
| | - Hong-Yan Lu
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Ping Zhang
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China. .,Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
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21
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Toyama H, Akiyama R, Ichinokura S, Hashizume M, Iimori T, Endo Y, Hobara R, Matsui T, Horii K, Sato S, Hirahara T, Komori F, Hasegawa S. Two-Dimensional Superconductivity of Ca-Intercalated Graphene on SiC: Vital Role of the Interface between Monolayer Graphene and the Substrate. ACS NANO 2022; 16:3582-3592. [PMID: 35209713 DOI: 10.1021/acsnano.1c11161] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ca-intercalation has enabled superconductivity in graphene on SiC. However, the atomic and electronic structures that are critical for superconductivity are still under discussion. We find an essential role of the interface between monolayer graphene and the SiC substrate for superconductivity. In the Ca-intercalation process, at the interface a carbon layer terminating SiC changes to graphene by Ca-termination of SiC (monolayer graphene becomes a bilayer), inducing more electrons than a free-standing model. Then, Ca is intercalated in between the graphene layers, which shows superconductivity with the updated critical temperature (TC) of up to 5.7 K. In addition, the relation between TC and the normal-state conductivity is unusual, "dome-shaped". These findings are beyond the simple C6CaC6 model in which s-wave BCS superconductivity is theoretically predicted. This work proposes a general picture of the intercalation-induced superconductivity in graphene on SiC and indicates the potential for superconductivity induced by other intercalants.
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Affiliation(s)
- Haruko Toyama
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Ryota Akiyama
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Satoru Ichinokura
- Department of Physics, Tokyo Institution of Technology, Meguro, Tokyo 152-8551, Japan
| | - Mizuki Hashizume
- Department of Physics, Tokyo Institution of Technology, Meguro, Tokyo 152-8551, Japan
| | - Takushi Iimori
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yukihiro Endo
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Rei Hobara
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Tomohiro Matsui
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Kentaro Horii
- Department of Physics, Tokyo Institution of Technology, Meguro, Tokyo 152-8551, Japan
| | - Shunsuke Sato
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Toru Hirahara
- Department of Physics, Tokyo Institution of Technology, Meguro, Tokyo 152-8551, Japan
| | - Fumio Komori
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Shuji Hasegawa
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
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22
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Bai Z, He D, Fu S, Miao Q, Liu S, Huang M, Zhao K, Wang Y, Zhang X. Recent progress in electron–phonon interaction of two‐dimensional materials. NANO SELECT 2022. [DOI: 10.1002/nano.202100367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Zhiying Bai
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Dawei He
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Shaohua Fu
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Qing Miao
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Shuangyan Liu
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Mohan Huang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Kun Zhao
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Yongsheng Wang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Xiaoxian Zhang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
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23
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Liu L, Wang C, Zhang L, Liu C, Niu C, Zeng Z, Ma D, Jia Y. Surface Van Hove Singularity Enabled Efficient Catalysis in Low-Dimensional Systems: CO Oxidation and Hydrogen Evolution Reactions. J Phys Chem Lett 2022; 13:740-746. [PMID: 35029120 DOI: 10.1021/acs.jpclett.1c03861] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Surface Van Hove singularity (SVHS) triggers exciting physical phenomena distinct from the bulk. Herein, we explore the potential role of SVHS in catalysis for both CO oxidation and the hydrogen evolution reaction (HER) using the graphene/Ca2N (Gra/Ca2N) heterojunction and Pt2HgSe3 (001) surface as prototype systems. It is demonstrated that both systems with SVHS could serve as an electron bath to promote O2 adsorption and subsequent CO oxidation with low energy barriers of 0.2-0.6 eV for the Gra/Ca2N and Pt2HgSe3 (001) surface and similarly facilitate the HER with near-zero hydrogen adsorption free energy. Importantly, the catalytically active sites associated with SVHS are well-defined and distributed over the whole surface plane, and further, the chemical reactivity of SVHS can also be tuned easily via adjusting its position with respect to EF. Our study demonstrates the enabling power of SVHS and provides novel physical insights into the promising potential role of VHS in designing high-efficiency catalysts.
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Affiliation(s)
- Liangliang Liu
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, School of Materials, Henan University, Kaifeng 475004, China
- Key Laboratory for Quantum Materials of Henan, and Center for Topological Functional Materials, Henan University, Kaifeng 475004, China
| | - Chunyan Wang
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, School of Materials, Henan University, Kaifeng 475004, China
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Liying Zhang
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, School of Materials, Henan University, Kaifeng 475004, China
| | - Chengyan Liu
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, School of Materials, Henan University, Kaifeng 475004, China
| | - Chunyao Niu
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Zaiping Zeng
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, School of Materials, Henan University, Kaifeng 475004, China
| | - Dongwei Ma
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, School of Materials, Henan University, Kaifeng 475004, China
- Key Laboratory for Quantum Materials of Henan, and Center for Topological Functional Materials, Henan University, Kaifeng 475004, China
| | - Yu Jia
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, School of Materials, Henan University, Kaifeng 475004, China
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
- Key Laboratory for Quantum Materials of Henan, and Center for Topological Functional Materials, Henan University, Kaifeng 475004, China
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24
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Yan L, Wang BT, Huang X, Li Q, Xue K, Zhang J, Ren W, Zhou L. Surface passivation induced a significant enhancement of superconductivity in layered two-dimensional MSi 2N 4 (M = Ta and Nb) materials. NANOSCALE 2021; 13:18947-18954. [PMID: 34755746 DOI: 10.1039/d1nr05560g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two-dimensional (2D) transition metal di-nitrides (TMN2) have been arousing great interest for their unique mechanic, electronic, optoelectronic, and magnetic properties. The recent successful growth of monolayer MSi2N4 (M = Mo and W) further motivates us to explore new physics and unusual properties behind this family. By using first-principles calculations and Bardeen-Cooper-Schrieffer theory, we predicted the existence of the superconductivity in single-layer (SL) 1T- and 1H-TaN2 with superconducting transition temperatures (Tc) of ∼0.86 and 1.3 K. Specifically, the Tc could be greatly enhanced to ∼24.6 K by passivating the TaN2 monolayer with Si-N bilayers. Furthermore, the superconductivity could be increased to ∼30.4 K via substituting lighter Nb for Ta. This enhancement of superconductivity mainly stems from the softer vibration modes consisting of in-plane Ta/Nb vibrations mixed with Si-xy vibrations. The superconductivity can be further tuned by applying external strains and carrier doping. This enhancement strategy of surface passivation and light atom substitution would suggest a new platform for 2D superconductors and provide an instructive pathway for next-generation nanoelectronics.
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Affiliation(s)
- Luo Yan
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China.
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313001, China
| | - Bao-Tian Wang
- Institute of High Energy Physics, Chinese Academy of Science (CAS), Beijing 10049, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Xingyong Huang
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China.
| | - Qiaoqiao Li
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China.
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313001, China
| | - Kui Xue
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China.
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313001, China
| | - Jing Zhang
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China.
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313001, China
| | - Wencai Ren
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, P. R. China
- School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, P. R. China
| | - Liujiang Zhou
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China.
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313001, China
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25
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Wang C, Wang H, Chen W, Xie X, Zong J, Liu L, Jin S, Zhang Y, Yu F, Meng Q, Tian Q, Wang L, Ren W, Li F, Zhang H, Zhang Y. Direct Observation of Global Elastic Intervalley Scattering Induced by Impurities on Graphene. NANO LETTERS 2021; 21:8258-8265. [PMID: 34570496 DOI: 10.1021/acs.nanolett.1c02714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The scattering process induced by impurities in graphene plays a key role in transport properties. Especially, the disorder impurities can drive the ordered state with a hexagonal superlattice on graphene by electron-mediated interaction at a transition temperature. Using angle-resolved photoemission spectroscopy (ARPES), we reveal that the epitaxial monolayer and bilayer graphene with various impurities display global elastic intervalley scattering and quantum interference below the critical temperature (34 K), which leads to a set of new folded Dirac cones at the Brillouin-zone center by mixing two inequivalent Dirac cones. The Dirac electrons generated from intervalley scattering without chirality can be due to the breaking of the sublattice symmetry. In addition, the temperature-dependent ARPES measurements indicate the thermal damping of quantum interference patterns from Dirac electron scattering on impurities. Our results demonstrate that the electron scattering and interference induced by impurities can completely modulate the Dirac bands of graphene.
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Affiliation(s)
- 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
| | - Huaiqiang 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
| | - Wang Chen
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
| | - Xuedong Xie
- 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
| | - Lulu Liu
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
| | - Shaoen Jin
- National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China
| | - Yongheng Zhang
- 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
| | - Qinghao Meng
- 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
| | - Li Wang
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China
| | - Wei Ren
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China
| | - Fangsen Li
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China
| | - Haijun 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
| | - 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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26
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Shen D, Liu Y, Li M, Dong W, Yang F, Wang L, Yang S, Sun W. First-principles calculations on the deposition behavior of Li xNa y ( x + y ≤ 5) clusters during the hybrid storage of Li and Na atoms on graphene. Phys Chem Chem Phys 2021; 23:21817-21824. [PMID: 34553716 DOI: 10.1039/d1cp01237a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A new strategy of sodium ion batteries with the hybrid storage of Li and Na ions has attracted much attention in the field of large-scale energy storage. For revealing the mechanism of hybrid storage of Li and Na atoms in carbon materials, the lowest energy configuration, adsorption energy, differential charge density and density of states of LixNay clusters on graphene, as a structural unit of carbon materials, were calculated and investigated based on first principles density functional theory. The calculation results show that the deposition behavior of single Li or Na atoms on graphene is similar, and both are preferentially deposited at the hollow of graphene (H-site). The Li atom is deposited preferentially over the Na atom, and the deposition height of the Li atom is lower. When the total number of metal atoms x + y ≥ 3, LixNay clusters are deposited on graphene in the form of a stereotypical atomic cluster, in which the Li atom is usually at the bottom of the LixNay cluster, while the Na atom is usually at the top of the cluster. The electronic structure analysis shows that the electrons of the LixNay cluster are transferred to the anti-bonding π orbitals adjacent to graphene. The 2s orbitals of Li atoms and the 2s and 2p orbitals of Na atoms are hybridized with the 2p orbitals of C atoms. Therefore, the Li-C bonds or Na-C bonds formed between Li or Na atoms and C atoms of graphene are usually ionic bonds with partial covalent bond properties. Meanwhile, the Li-Li, Na-Na or Li-Na bonds formed inside LixNay clusters are usually multiple metal-metal bonds.
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Affiliation(s)
- Ding Shen
- College of Materials Science and Engineering, Liaoning Technical University, Fuxin, Liaoning 123000, China. .,School of Mechanics and Engineering, Liaoning Technical University, Fuxin 123000, China
| | - Yaohan Liu
- College of Materials Science and Engineering, Liaoning Technical University, Fuxin, Liaoning 123000, China.
| | - Mingyue Li
- College of Materials Science and Engineering, Liaoning Technical University, Fuxin, Liaoning 123000, China.
| | - Wei Dong
- College of Materials Science and Engineering, Liaoning Technical University, Fuxin, Liaoning 123000, China.
| | - Fang Yang
- College of Materials Science and Engineering, Liaoning Technical University, Fuxin, Liaoning 123000, China.
| | - Laigui Wang
- School of Mechanics and Engineering, Liaoning Technical University, Fuxin 123000, China
| | - Shaobin Yang
- College of Materials Science and Engineering, Liaoning Technical University, Fuxin, Liaoning 123000, China.
| | - Wen Sun
- College of Materials Science and Engineering, Liaoning Technical University, Fuxin, Liaoning 123000, China. .,College of Mining Engineering, Liaoning Technical University, Fuxin 123000, China
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27
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Zhang H, Bao C, Schüler M, Zhou S, Li Q, Luo L, Yao W, Wang Z, Devereaux TP, Zhou S. Self-energy dynamics and mode-specific phonon threshold effect in a Kekulé-ordered graphene. Natl Sci Rev 2021; 9:nwab175. [PMID: 35663240 PMCID: PMC9155635 DOI: 10.1093/nsr/nwab175] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 09/08/2021] [Accepted: 09/08/2021] [Indexed: 11/14/2022] Open
Abstract
Abstract
Electron-phonon interaction and related self-energy are fundamental to both the equilibrium properties and non-equilibrium relaxation dynamics of solids. Although electron-phonon interaction has been suggested by various time-resolved measurements to be important for the relaxation dynamics of graphene, the lack of energy- and momentum-resolved self-energy dynamics prohibits direct identification of the role of specific phonon modes in the relaxation dynamics. Here by performing time- and angle-resolved photoemission spectroscopy measurements on a Kekulé-ordered graphene with folded Dirac cones at the Γ point, we have succeeded in resolving the self-energy effect induced by coupling of electrons to two phonons at Ω1 = 177 meV and Ω2 = 54 meV and revealing its dynamical change in the time domain. Moreover, these strongly coupled phonons define energy thresholds, which separate the hierarchical relaxation dynamics from ultrafast, fast to slow, thereby providing direct experimental evidence for the dominant role of mode-specific phonons in the relaxation dynamics.
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Affiliation(s)
- Hongyun Zhang
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Changhua Bao
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Michael Schüler
- Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Shaohua Zhou
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Qian Li
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Laipeng Luo
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Wei Yao
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Zhong Wang
- Institute for Advanced Study, Tsinghua University, Beijing, 100084, P. R. China
| | - Thomas P Devereaux
- Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94035, USA
| | - Shuyun Zhou
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, P. R. China
- Frontier Science Center for Quantum Information, Beijing 100084, P. R. China
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28
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Bo T, Wang Y, Liang Y, Liu X, Ren J, Weng H, Liu M, Meng S. High-Throughput Screening of Element-Doped Carbon Nanotubes Toward an Optimal One-Dimensional Superconductor. J Phys Chem Lett 2021; 12:6667-6675. [PMID: 34255528 DOI: 10.1021/acs.jpclett.1c02000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In order to search for optimal one-dimensional (1D) superconductors with a high transition temperature (Tc), we performed high-throughput computation on the phonon dispersion, electron-phonon coupling (EPC), and superconducting properties of (5,0), (3,3), and element-doped (3,3) carbon nanotubes (CNTs) based on first-principles calculations. We find that the CNT (5,0) is superconductive with Tc of 7.9 K, while the (3,3) CNT has no superconductivity. However, by high-throughput screening of about 50 elements in the periodic table, we identified that 14 elemental dopants can make the (3,3) CNT dynamically stable and superconducting. The high Tc ≈ 28 K suggests that the Si-doped (3,3) CNT is an excellent one-dimensional (1D) superconductor. In addition, the Al-, In-, and La-doped (3,3) CNTs are also great 1D superconductor candidates with a Tc of about 18, 17, and 29 K, respectively. These results may inspire the synthesis and discovery of optimal high-Tc 1D superconductors experimentally.
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Affiliation(s)
- Tao Bo
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yanan Wang
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yingzong Liang
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xinbao Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jun Ren
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Hongming Weng
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Miao Liu
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Sheng Meng
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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29
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Bao C, Zhang H, Zhang T, Wu X, Luo L, Zhou S, Li Q, Hou Y, Yao W, Liu L, Yu P, Li J, Duan W, Yao H, Wang Y, Zhou S. Experimental Evidence of Chiral Symmetry Breaking in Kekulé-Ordered Graphene. PHYSICAL REVIEW LETTERS 2021; 126:206804. [PMID: 34110212 DOI: 10.1103/physrevlett.126.206804] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
The low-energy excitations of graphene are relativistic massless Dirac fermions with opposite chiralities at valleys K and K^{'}. Breaking the chiral symmetry could lead to gap opening in analogy to dynamical mass generation in particle physics. Here we report direct experimental evidences of chiral symmetry breaking (CSB) from both microscopic and spectroscopic measurements in a Li-intercalated graphene. The CSB is evidenced by gap opening at the Dirac point, Kekulé-O type modulation, and chirality mixing near the gap edge. Our work opens up opportunities for investigating CSB related physics in a Kekulé-ordered graphene.
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Affiliation(s)
- Changhua Bao
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Hongyun Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Teng Zhang
- School of Information and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Xi Wu
- Shenzhen Geim Graphene Center and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, People's Republic of China
| | - Laipeng Luo
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Shaohua Zhou
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Qian Li
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Yanhui Hou
- School of Information and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Wei Yao
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Liwei Liu
- School of Information and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Pu Yu
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
| | - Jia Li
- Shenzhen Geim Graphene Center and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, People's Republic of China
| | - Wenhui Duan
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
| | - Hong Yao
- Institute for Advanced Study, Tsinghua University, Beijing 100084, People's Republic of China
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Yeliang Wang
- School of Information and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Shuyun Zhou
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
- Beijing Advanced Innovation Center for Future Chip, Beijing 100084, People's Republic of China
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30
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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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31
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Penev ES, Marzari N, Yakobson BI. Theoretical Prediction of Two-Dimensional Materials, Behavior, and Properties. ACS NANO 2021; 15:5959-5976. [PMID: 33823108 DOI: 10.1021/acsnano.0c10504] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Predictive modeling of two-dimensional (2D) materials is at the crossroad of two current rapidly growing interests: 2D materials per se, massively sought after and explored in experimental laboratories, and materials theoretical-computational models in general, flourishing on a fertile mix of condensed-matter physics and chemistry with advancing computational technology. Here the general methods and specific techniques of modeling are briefly overviewed, along with a somewhat philosophical assessment of what "prediction" is, followed by selected practical examples for 2D materials, from structures and properties, to device functionalities and synthetic routes for their making. We conclude with a brief sketch-outlook of future developments.
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Affiliation(s)
| | - 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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32
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Begunovich LV, Kuklin AV, Baryshnikov GV, Valiev RR, Ågren H. Single-layer polymeric tetraoxa[8]circulene modified by s-block metals: toward stable spin qubits and novel superconductors. NANOSCALE 2021; 13:4799-4811. [PMID: 33629695 DOI: 10.1039/d0nr08554e] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Tunable electronic properties of low-dimensional materials have been the object of extensive research, as such properties are highly desirable in order to provide flexibility in the design and optimization of functional devices. In this study, we account for the fact that such properties can be tuned by embedding diverse metal atoms and theoretically study a series of new organometallic porous sheets based on two-dimensional tetraoxa[8]circulene (TOC) polymers doped with alkali or alkaline-earth metals. The results reveal that the metal-decorated sheets change their electronic structure from semiconducting to metallic behaviour due to n-doping. Complete active space self-consistent field (CASSCF) calculations reveal a unique open-shell singlet ground state in the TOC-Ca complex, which is formed by two closed-shell species. Moreover, Ca becomes a doublet state, which is promising for magnetic quantum bit applications due to the long spin coherence time. Ca-doped TOC also demonstrates a high density of states in the vicinity of the Fermi level and induced superconductivity. Using the ab initio Eliashberg formalism, we find that the TOC-Ca polymers are phonon-mediated superconductors with a critical temperature TC = 14.5 K, which is within the range of typical carbon based superconducting materials. Therefore, combining the proved superconductivity and the long spin lifetime in doublet Ca, such materials could be an ideal platform for the realization of quantum bits.
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Affiliation(s)
- Lyudmila V Begunovich
- International Research Center of Spectroscopy and Quantum Chemistry (IRC SQC), Siberian Federal University, 26 Kirensky st., 660074, Krasnoyarsk, Russia.
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Rosenzweig P, Karakachian H, Marchenko D, Küster K, Starke U. Overdoping Graphene beyond the van Hove Singularity. PHYSICAL REVIEW LETTERS 2020; 125:176403. [PMID: 33156643 DOI: 10.1103/physrevlett.125.176403] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
At very high doping levels the van Hove singularity in the π^{*} band of graphene becomes occupied and exotic ground states possibly emerge, driven by many-body interactions. Employing a combination of ytterbium intercalation and potassium adsorption, we n dope epitaxial graphene on silicon carbide past the π^{*} van Hove singularity, up to a charge carrier density of 5.5×10^{14} cm^{-2}. This regime marks the unambiguous completion of a Lifshitz transition in which the Fermi surface topology has evolved from two electron pockets into a giant hole pocket. Angle-resolved photoelectron spectroscopy confirms these changes to be driven by electronic structure renormalizations rather than a rigid band shift. Our results open up the previously unreachable beyond-van-Hove regime in the phase diagram of epitaxial graphene, thereby accessing an unexplored landscape of potential exotic phases in this prototype two-dimensional material.
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Affiliation(s)
- Philipp Rosenzweig
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Hrag Karakachian
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Dmitry Marchenko
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Kathrin Küster
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Ulrich Starke
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
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34
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Kochan D, Barth M, Costa A, Richter K, Fabian J. Spin Relaxation in s-Wave Superconductors in the Presence of Resonant Spin-Flip Scatterers. PHYSICAL REVIEW LETTERS 2020; 125:087001. [PMID: 32909806 DOI: 10.1103/physrevlett.125.087001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 05/22/2020] [Accepted: 07/22/2020] [Indexed: 06/11/2023]
Abstract
Employing analytical methods and quantum transport simulations we investigate the relaxation of quasiparticle spins in graphene proximitized by an s-wave superconductor in the presence of resonant magnetic and spin-orbit active impurities. Off resonance, the relaxation increases with decreasing temperature when electrons scatter off magnetic impurities-the Hebel-Slichter effect-and decreases when impurities have spin-orbit coupling. This distinct temperature dependence (not present in the normal state) uniquely discriminates between the two scattering mechanisms. However, we show that the Hebel-Slichter picture breaks down at resonances. The emergence of Yu-Shiba-Rusinov bound states within the superconducting gap redistributes the spectral weight away from magnetic resonances. The result is opposite to the Hebel-Slichter expectation: the spin relaxation decreases with decreasing temperature. Our findings hold for generic s-wave superconductors with resonant magnetic impurities, but also, as we show, for resonant magnetic Josephson junctions.
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Affiliation(s)
- Denis Kochan
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | - Michael Barth
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | - Andreas Costa
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | - Klaus Richter
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | - Jaroslav Fabian
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
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35
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Szewczyk KA, Domagalska IA, Durajski AP, Szczęśniak R. Nonadiabatic superconductivity in a Li-intercalated hexagonal boron nitride bilayer. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:1178-1189. [PMID: 32821642 PMCID: PMC7418097 DOI: 10.3762/bjnano.11.102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
When considering a Li-intercalated hexagonal boron nitride bilayer (Li-hBN), the vertex corrections of electron-phonon interaction cannot be omitted. This is evidenced by the very high value of the ratio λωD/εF ≈ 0.46, where λ is the electron-phonon coupling constant, ωD is the Debye frequency, and εF represents the Fermi energy. Due to nonadiabatic effects, the phonon-induced superconducting state in Li-hBN is characterized by much lower values of the critical temperature (T LOVC C ∈ {19.1, 15.5, 11.8} K, for μ* ∈ {0.1, 0.14, 0.2}, respectively) than would result from calculations not taking this effect into account (T ME C∈ {31.9, 26.9, 21} K). From the technological point of view, the low value of T C limits the possible applications of Li-hBN. The calculations were carried out under the classic Migdal-Eliashberg formalism (ME) and the Eliashberg theory with lowest-order vertex corrections (LOVC). We show that the vertex corrections of higher order (λ3) lower the value of T LOVC C by a few percent.
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Affiliation(s)
- Kamila A Szewczyk
- Division of Theoretical Physics, Jan Długosz University in Częstochowa, Ave. Armii Krajowej 13/15, 42-200 Częstochowa, Poland
| | - Izabela A Domagalska
- Quantum Optics and Engineering Division, Faculty of Physics and Astronomy, University of Zielona Góra, Prof. Z. Szafrana 4a, 65-516 Zielona Góra, Poland
| | - Artur P Durajski
- Division of Physics, Częstochowa University of Technology, Ave. Armii Krajowej 19, 42-200 Częstochowa, Poland
| | - Radosław Szczęśniak
- Division of Theoretical Physics, Jan Długosz University in Częstochowa, Ave. Armii Krajowej 13/15, 42-200 Częstochowa, Poland
- Division of Physics, Częstochowa University of Technology, Ave. Armii Krajowej 19, 42-200 Częstochowa, Poland
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36
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Shimada NH, Minamitani E, Watanabe S. Theoretical prediction of superconductivity in monolayer h-BN doped with alkaline-earth metals (Ca, Sr, Ba). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:435002. [PMID: 32668422 DOI: 10.1088/1361-648x/aba674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 07/15/2020] [Indexed: 06/11/2023]
Abstract
We investigated the possibility of superconductivity in monolayer hexagonal boron nitride (h-BN) doped using group-1 (Li, Na, K) and group-2 (Be, Mg, Ca, Sr, Ba) atoms viaab initiocalculations. Consequently, we reveal that Sr- and Ba-doped monolayer h-BN and Ca-doped monolayer h-BN with 3.5% tensile strain are energetically stable and become superconductors with superconducting transition temperature (Tc) values of 5.83, 1.53, and 10.7 K, respectively, which are considerably higher than those of Ca-, Sr-, and Ba-doped graphene. In addition, the momentum-resolved electron-phonon coupling (EPC) constant shows that the scattering among intrinsic π* electrons around the Γ point governs Tc. The scattering process is mediated by the low-energy vibration of the adsorbate. Moreover, compared with graphene, the stronger adsorbate-substrate interaction and lower symmetry in h-BN are critical for enhancing the EPC in doped h-BN.
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Affiliation(s)
- Nao H Shimada
- Department of Materials Engineering, The University of Tokyo, Japan
| | - Emi Minamitani
- Institute for Molecular Science, Japan
- Japan Science and Technology Agency, PRESTO, Japan
| | - Satoshi Watanabe
- Department of Materials Engineering, The University of Tokyo, Japan
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37
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Yu JS, Liao JH, Zhao YJ, Zhao YC, Yang XB. Motif based high-throughput structure prediction of superconducting monolayer titanium boride. Phys Chem Chem Phys 2020; 22:16236-16243. [PMID: 32643728 DOI: 10.1039/d0cp01540g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Two-dimensional boron structures, due to their diverse properties, have attracted great attention because of their potential applications in nanoelectronic devices. A series of TiBn (2 ≤ n ≤ 13) monolayers are efficiently constructed through our motif based method and theoretically investigated through high-throughput first-principles calculations. The configurations are generated based on the motifs of boron dimeric/triangular/quadrilateral fragments and multi-coordinate titanium-centered boron molecular wheels. Besides previously reported TiB4 and TiB9 which were discovered by the global search method, we predict that high symmetry monolayer TiB7 (Cmmm), which is octa-coordinate titanium boride, is dynamically stable. The TiB7 monolayer is a BCS superconductor with a transition temperature Tc of up to 8.3 K. The motif based approach is proved to be efficient in searching stable structures with prior knowledge so that the potentially stable transition metal monolayers can be quickly constructed by using basic cluster motifs. As an efficient way of discovering materials, the method is easily extended to predict other types of materials which have common characteristic patterns in the structure.
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Affiliation(s)
- Ju-Song Yu
- Department of Physics, South China University of Technology, Guangzhou 510640, People's Republic of China.
| | - Ji-Hai Liao
- Department of Physics, South China University of Technology, Guangzhou 510640, People's Republic of China. and State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
| | - Yu-Jun Zhao
- Department of Physics, South China University of Technology, Guangzhou 510640, People's Republic of China.
| | - Yin-Chang Zhao
- Department of Physics, Yantai University, Yantai 264005, P. R. China
| | - Xiao-Bao Yang
- Department of Physics, South China University of Technology, Guangzhou 510640, People's Republic of China.
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38
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Electronic and Transport Properties of Epitaxial Graphene on SiC and 3C-SiC/Si: A Review. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10124350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The electronic and transport properties of epitaxial graphene are dominated by the interactions the material makes with its surroundings. Based on the transport properties of epitaxial graphene on SiC and 3C-SiC/Si substrates reported in the literature, we emphasize that the graphene interfaces formed between the active material and its environment are of paramount importance, and how interface modifications enable the fine-tuning of the transport properties of graphene. This review provides a renewed attention on the understanding and engineering of epitaxial graphene interfaces for integrated electronics and photonics applications.
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39
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Peltonen TJ, Heikkilä TT. Flat-band superconductivity in periodically strained graphene: mean-field and Berezinskii-Kosterlitz-Thouless transition. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:365603. [PMID: 32315990 DOI: 10.1088/1361-648x/ab8b9d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/21/2020] [Indexed: 06/11/2023]
Abstract
In the search of high-temperature superconductivity one option is to focus on increasing the density of electronic states. Here we study both the normal ands-wave superconducting state properties of periodically strained graphene, which exhibits approximate flat bands with a high density of states, with the flatness tunable by the strain profile. We generalize earlier results regarding a one-dimensional harmonic strain to arbitrary periodic strain fields, and further extend the results by calculating the superfluid weight and the Berezinskii-Kosterlitz-Thouless (BKT) transition temperatureTBKTto determine the true transition point. By numerically solving the self-consistency equation, we find a strongly inhomogeneous superconducting order parameter, similarly to twisted bilayer graphene. In the flat-band regime the order parameter magnitude, critical chemical potential, critical temperature, superfluid weight, and BKT transition temperature are all approximately linear in the interaction strength, which suggests that high-temperature superconductivity might be feasible in this system. We especially show that by using realistic strain strengthsTBKTcan be made much larger than in twisted bilayer graphene, if using similar interaction strengths. We also calculate properties such as the local density of states that could serve as experimental fingerprints for the presented model.
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Affiliation(s)
- Teemu J Peltonen
- University of Jyväskylä, Department of Physics and Nanoscience Center, PO Box 35 (YFL), FI-40014 University of Jyväskylä, Finland
| | - Tero T Heikkilä
- University of Jyväskylä, Department of Physics and Nanoscience Center, PO Box 35 (YFL), FI-40014 University of Jyväskylä, Finland
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40
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Briggs N, Bersch B, Wang Y, Jiang J, Koch RJ, Nayir N, Wang K, Kolmer M, Ko W, De La Fuente Duran A, Subramanian S, Dong C, Shallenberger J, Fu M, Zou Q, Chuang YW, Gai Z, Li AP, Bostwick A, Jozwiak C, Chang CZ, Rotenberg E, Zhu J, van Duin ACT, Crespi V, Robinson JA. Atomically thin half-van der Waals metals enabled by confinement heteroepitaxy. NATURE MATERIALS 2020; 19:637-643. [PMID: 32157191 DOI: 10.1038/s41563-020-0631-x] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 02/03/2020] [Indexed: 06/10/2023]
Abstract
Atomically thin two-dimensional (2D) metals may be key ingredients in next-generation quantum and optoelectronic devices. However, 2D metals must be stabilized against environmental degradation and integrated into heterostructure devices at the wafer scale. The high-energy interface between silicon carbide and epitaxial graphene provides an intriguing framework for stabilizing a diverse range of 2D metals. Here we demonstrate large-area, environmentally stable, single-crystal 2D gallium, indium and tin that are stabilized at the interface of epitaxial graphene and silicon carbide. The 2D metals are covalently bonded to SiC below but present a non-bonded interface to the graphene overlayer; that is, they are 'half van der Waals' metals with strong internal gradients in bonding character. These non-centrosymmetric 2D metals offer compelling opportunities for superconducting devices, topological phenomena and advanced optoelectronic properties. For example, the reported 2D Ga is a superconductor that combines six strongly coupled Ga-derived electron pockets with a large nearly free-electron Fermi surface that closely approaches the Dirac points of the graphene overlayer.
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Affiliation(s)
- Natalie Briggs
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, USA
- 2-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, PA, USA
| | - Brian Bersch
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, USA
| | - Yuanxi Wang
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, USA
- 2-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, PA, USA
| | - Jue Jiang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Roland J Koch
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Nadire Nayir
- 2-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, PA, USA
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Ke Wang
- Materials Research Institute, The Pennsylvania State University, University Park, PA, USA
| | - Marek Kolmer
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Wonhee Ko
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Ana De La Fuente Duran
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Shruti Subramanian
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, USA
| | - Chengye Dong
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, USA
| | - Jeffrey Shallenberger
- Materials Research Institute, The Pennsylvania State University, University Park, PA, USA
| | - Mingming Fu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Qiang Zou
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Ya-Wen Chuang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Zheng Gai
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - An-Ping Li
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Aaron Bostwick
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Chris Jozwiak
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Cui-Zu Chang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Eli Rotenberg
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Jun Zhu
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, USA
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Adri C T van Duin
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA
- 2-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, PA, USA
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA, USA
- Materials Research Institute, The Pennsylvania State University, University Park, PA, USA
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Vincent Crespi
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, USA
- 2-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, PA, USA
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
- Materials Research Institute, The Pennsylvania State University, University Park, PA, USA
| | - Joshua A Robinson
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA.
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, USA.
- 2-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, PA, USA.
- Materials Research Institute, The Pennsylvania State University, University Park, PA, USA.
- Center for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, PA, USA.
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Nigge P, Qu AC, Lantagne-Hurtubise É, Mårsell E, Link S, Tom G, Zonno M, Michiardi M, Schneider M, Zhdanovich S, Levy G, Starke U, Gutiérrez C, Bonn D, Burke SA, Franz M, Damascelli A. Room temperature strain-induced Landau levels in graphene on a wafer-scale platform. SCIENCE ADVANCES 2019; 5:eaaw5593. [PMID: 31723598 PMCID: PMC6839937 DOI: 10.1126/sciadv.aaw5593] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 09/17/2019] [Indexed: 05/17/2023]
Abstract
Graphene is a powerful playground for studying a plethora of quantum phenomena. One of the remarkable properties of graphene arises when it is strained in particular geometries and the electrons behave as if they were under the influence of a magnetic field. Previously, these strain-induced pseudomagnetic fields have been explored on the nano- and micrometer-scale using scanning probe and transport measurements. Heteroepitaxial strain, in contrast, is a wafer-scale engineering method. Here, we show that pseudomagnetic fields can be generated in graphene through wafer-scale epitaxial growth. Shallow triangular nanoprisms in the SiC substrate generate strain-induced uniform fields of 41 T, enabling the observation of strain-induced Landau levels at room temperature, as detected by angle-resolved photoemission spectroscopy, and confirmed by model calculations and scanning tunneling microscopy measurements. Our work demonstrates the feasibility of exploiting strain-induced quantum phases in two-dimensional Dirac materials on a wafer-scale platform, opening the field to new applications.
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Affiliation(s)
- P. Nigge
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - A. C. Qu
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - É. Lantagne-Hurtubise
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - E. Mårsell
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Division of Molecular and Condensed Matter Physics, Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 751 20 Uppsala, Sweden
| | - S. Link
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - G. Tom
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - M. Zonno
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - M. Michiardi
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - M. Schneider
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - S. Zhdanovich
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - G. Levy
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - U. Starke
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - C. Gutiérrez
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - D. Bonn
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - S. A. Burke
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Corresponding author. (S.A.B.); (M.F.); (A.D.)
| | - M. Franz
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Corresponding author. (S.A.B.); (M.F.); (A.D.)
| | - A. Damascelli
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Corresponding author. (S.A.B.); (M.F.); (A.D.)
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Meng LB, Zhou MJ, Zhang YJ, Ni S. Intrinsic phonon-mediated superconductivity in graphene-like BSi lattice. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:345401. [PMID: 31096196 DOI: 10.1088/1361-648x/ab21eb] [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
The research of new superconductors is an ongoing field for the fundamental significances and potential applications, and two-dimensional (2D) nanomaterials open a new alluring branch for exploration. Here we predict by first-principles calculations that 2D pristine graphene-like BSi monolayer is a phonon-mediated superconductor above the boiling point of liquid helium. The intrinsic covalent-metallic ground state, large density of states at Fermi energy, proper electronic organization as well as strong coupling of out-of-plane phonons and electrons endow an intermediate electron-phonon coupling of ~1.12, rendering this honeycomb sheet as a conventional superconductor with a relatively high T c ~ 11 K. As the global minimum structure in the 2D space previously predicted, this superconducting BSi monolayer may be feasible experimentally. Our finding provides a new field of superconducting nanomaterials for study.
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Affiliation(s)
- L-B Meng
- Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, People's Republic of China
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Bekaert J, Petrov M, Aperis A, Oppeneer PM, Milošević MV. Hydrogen-Induced High-Temperature Superconductivity in Two-Dimensional Materials: The Example of Hydrogenated Monolayer MgB_{2}. PHYSICAL REVIEW LETTERS 2019; 123:077001. [PMID: 31491112 DOI: 10.1103/physrevlett.123.077001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 04/23/2019] [Indexed: 06/10/2023]
Abstract
Hydrogen-based compounds under ultrahigh pressure, such as the polyhydrides H_{3}S and LaH_{10}, superconduct through the conventional electron-phonon coupling mechanism to attain the record critical temperatures known to date. Here we exploit the intrinsic advantages of hydrogen to strongly enhance phonon-mediated superconductivity in a completely different system, namely, a two-dimensional material with hydrogen adatoms. We find that van Hove singularities in the electronic structure, originating from atomiclike hydrogen states, lead to a strong increase of the electronic density of states at the Fermi level, and thus of the electron-phonon coupling. Additionally, the emergence of high-frequency hydrogen-related phonon modes in this system boosts the electron-phonon coupling further. As a concrete example, we demonstrate the effect of hydrogen adatoms on the superconducting properties of monolayer MgB_{2}, by solving the fully anisotropic Eliashberg equations, in conjunction with a first-principles description of the electronic and vibrational states, and their coupling. We show that hydrogenation leads to a high critical temperature of 67 K, which can be boosted to over 100 K by biaxial tensile strain.
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Affiliation(s)
- J Bekaert
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - M Petrov
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - A Aperis
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden
| | - P M Oppeneer
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden
| | - M V Milošević
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
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Ab Initio Study of the Electronic, Vibrational, and Mechanical Properties of the Magnesium Diboride Monolayer. CONDENSED MATTER 2019. [DOI: 10.3390/condmat4020037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Magnesium diboride gained significant interest in the materials science community after the discovery of its superconductivity, with an unusually high critical temperature of 39 K. Many aspects of the electronic properties and superconductivity of bulk MgB 2 and thin sheets of MgB 2 have been determined; however, a single layer of MgB 2 has not yet been fully theoretically investigated. Here, we present a detailed study of the structural, electronic, vibrational, and elastic properties of monolayer MgB 2 , based on ab initio methods. First-principles calculations reveal the importance of reduction of dimensionality on the properties of MgB 2 and thoroughly describe the properties of this novel 2D material. The presence of a negative Poisson ratio, higher density of states at the Fermi level, and a good dynamic stability under strain make the MgB 2 monolayer a prominent material, both for fundamental research and application studies.
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Durajski AP, Skoczylas KM, Szcze Combining Cedilla Śniak R. Superconductivity in bilayer graphene intercalated with alkali and alkaline earth metals. Phys Chem Chem Phys 2019; 21:5925-5931. [PMID: 30785457 DOI: 10.1039/c9cp00176j] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
With the enormous research activity focused on graphene in recent years, it is not surprising that graphene superconductivity has become an attractive area of research. To date, no superconducting properties have been experimentally observed in the pristine form of graphene but controllable structure manipulation is a promising way to induce a superconducting state in graphene-based systems. Therefore, herein we investigate the possible superconductivity in two-layer graphene intercalated with atoms of alkali and alkaline earth metals. Results of our calculations conducted within the framework of density functional theory combined with the Eliashberg theory allow us to conclude that the Cooper pairing in these superconductors can be described in a standard phonon-mediated scenario. In this regime, C6XC6 (X = K, Ca, Rb and Sr) are expected to be superconductors with estimated superconducting critical temperatures of 5.47-14.56 K and with the ratios of energy gap to transition temperature exceeding the value predicted by the Bardeen-Cooper-Schrieffer theory.
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Affiliation(s)
- Artur P Durajski
- Institute of Physics, Cze[combining cedilla]stochowa University of Technology, Ave. Armii Krajowej 19, 42-200 Cze[combining cedilla]stochowa, Poland.
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Halle J, Néel N, Kröger J. Tailoring Intercalant Assemblies at the Graphene-Metal Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:2554-2560. [PMID: 30665296 DOI: 10.1021/acs.langmuir.8b03879] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The influence of graphene on the assembly of intercalated material is studied using low-temperature scanning tunneling microscopy. Intercalation of Pt under monolayer graphene on Pt(111) induces a substrate reconstruction that is qualitatively different from the lattice rearrangement induced by metal deposition on Pt(111) and, specifically, the homoepitaxy of Pt. Alkali metals Cs and Li are used as intercalants for monolayer and bilayer graphene on Ru(0001). Atomically resolved topographic data reveal that at elevated alkali metal coverage (2 × 2)Cs and (1 × 1)Li intercalant structures form with respect to the graphene lattice.
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Affiliation(s)
- Johannes Halle
- Institut für Physik , Technische Universität Ilmenau , D-98693 Ilmenau , Germany
| | - Nicolas Néel
- Institut für Physik , Technische Universität Ilmenau , D-98693 Ilmenau , Germany
| | - Jörg Kröger
- Institut für Physik , Technische Universität Ilmenau , D-98693 Ilmenau , Germany
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Yan L, Bo T, Zhang W, Liu PF, Lu Z, Xiao YG, Tang MH, Wang BT. Novel structures of two-dimensional tungsten boride and their superconductivity. Phys Chem Chem Phys 2019; 21:15327-15338. [DOI: 10.1039/c9cp02727k] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
We predict four new tungsten boride monolayers and demonstrate that two of them are phonon-mediated superconductors with superconducting transition temperatures of 7.8 and 1.5 K.
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Affiliation(s)
- Luo Yan
- Key Laboratory of Key Film Materials & Application for Equipments (Hunan Province)
- School of Material Sciences and Engineering
- Xiangtan University
- Xiangtan
- China
| | - Tao Bo
- Institute of High Energy Physics
- Chinese Academy of Sciences (CAS)
- Beijing 100049
- China
- Dongguan Institute of Neutron Science (DINS)
| | - Wenxue Zhang
- Collaborative Innovation Center of Extreme Optics
- Shanxi University
- Taiyuan
- China
- State Key Laboratory of Quantum Optics and Quantum Optics Devices
| | - Peng-Fei Liu
- Institute of High Energy Physics
- Chinese Academy of Sciences (CAS)
- Beijing 100049
- China
- Dongguan Institute of Neutron Science (DINS)
| | - Zhansheng Lu
- College of Physics and Materials Science
- Henan Normal University
- Xinxiang 453007
- China
| | - Yong-Guang Xiao
- Key Laboratory of Key Film Materials & Application for Equipments (Hunan Province)
- School of Material Sciences and Engineering
- Xiangtan University
- Xiangtan
- China
| | - Ming-Hua Tang
- Key Laboratory of Key Film Materials & Application for Equipments (Hunan Province)
- School of Material Sciences and Engineering
- Xiangtan University
- Xiangtan
- China
| | - Bao-Tian Wang
- Institute of High Energy Physics
- Chinese Academy of Sciences (CAS)
- Beijing 100049
- China
- Dongguan Institute of Neutron Science (DINS)
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Gholami R, Moradian R, Moradian S, Pickett WE. Superconducting Phases in Lithium Decorated Graphene LiC 6. Sci Rep 2018; 8:13795. [PMID: 30218026 PMCID: PMC6138680 DOI: 10.1038/s41598-018-32050-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 08/31/2018] [Indexed: 11/09/2022] Open
Abstract
A study of possible superconducting phases of graphene has been constructed in detail. A realistic tight binding model, fit to ab initio calculations, accounts for the Li-decoration of graphene with broken lattice symmetry, and includes s and d symmetry Bloch character that influences the gap symmetries that can arise. The resulting seven hybridized Li-C orbitals that support nine possible bond pairing amplitudes. The gap equation is solved for all possible gap symmetries. One band is weakly dispersive near the Fermi energy along Γ → M where its Bloch wave function has linear combination of [Formula: see text] and dxy character, and is responsible for [Formula: see text] and dxy pairing with lowest pairing energy in our model. These symmetries almost preserve properties from a two band model of pristine graphene. Another part of this band, along K → Γ, is nearly degenerate with upper s band that favors extended s wave pairing which is not found in two band model. Upon electron doping to a critical chemical potential μ1 = 0.22 eV the pairing potential decreases, then increases until a second critical value μ2 = 1.3 eV at which a phase transition to a distorted s-wave occurs. The distortion of d- or s-wave phases are a consequence of decoration which is not appear in two band pristine model. In the pristine graphene these phases convert to usual d-wave or extended s-wave pairing.
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Affiliation(s)
- Rouhollah Gholami
- Physics Department, Faculty of Science Razi University, Kermanshah, Iran
| | - Rostam Moradian
- Physics Department, Faculty of Science Razi University, Kermanshah, Iran. .,Nano science and nano technology research center, Razi University, Kermanshah, Iran.
| | - Sina Moradian
- Department of Electrical and Computer Engineering, University of Central Florida, Orlando, Florida, USA
| | - Warren E Pickett
- Department of Physics UC Davis, One Shield Avenue, Davis, CA, 95616, USA
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Hell MG, Ehlen N, Senkovskiy BV, Hasdeo EH, Fedorov A, Dombrowski D, Busse C, Michely T, di Santo G, Petaccia L, Saito R, Grüneis A. Resonance Raman Spectrum of Doped Epitaxial Graphene at the Lifshitz Transition. NANO LETTERS 2018; 18:6045-6056. [PMID: 30157652 DOI: 10.1021/acs.nanolett.8b02979] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We employ ultra-high vacuum (UHV) Raman spectroscopy in tandem with angle-resolved photoemission (ARPES) to investigate the doping-dependent Raman spectrum of epitaxial graphene on Ir(111). The evolution of Raman spectra from pristine to heavily Cs doped graphene up to a carrier concentration of 4.4 × 1014 cm-2 is investigated. At this doping, graphene is at the onset of the Lifshitz transition and renormalization effects reduce the electronic bandwidth. The optical transition at the saddle point in the Brillouin zone then becomes experimentally accessible by ultraviolet (UV) light excitation, which achieves resonance Raman conditions in close vicinity to the van Hove singularity in the joint density of states. The position of the Raman G band of fully doped graphene/Ir(111) shifts down by ∼60 cm-1. The G band asymmetry of Cs doped epitaxial graphene assumes an unusual strong Fano asymmetry opposite to that of the G band of doped graphene on insulators. Our calculations can fully explain these observations by substrate dependent quantum interference effects in the scattering pathways for vibrational and electronic Raman scattering.
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Affiliation(s)
- Martin G Hell
- II. Physikalisches Institut , Universität zu Köln , Zülpicher Strasse 77 , 50937 Köln , Germany
| | - Niels Ehlen
- II. Physikalisches Institut , Universität zu Köln , Zülpicher Strasse 77 , 50937 Köln , Germany
| | - Boris V Senkovskiy
- II. Physikalisches Institut , Universität zu Köln , Zülpicher Strasse 77 , 50937 Köln , Germany
| | - Eddwi H Hasdeo
- Department of Physics , Tohoku University , Sendai 980-8578 , Japan
- Research Center for Physics , Indonesian Institute of Sciences , Kawasan Puspiptek Serpong , Tangerang Selatan 15314 , Indonesia
| | - Alexander Fedorov
- II. Physikalisches Institut , Universität zu Köln , Zülpicher Strasse 77 , 50937 Köln , Germany
| | - Daniela Dombrowski
- II. Physikalisches Institut , Universität zu Köln , Zülpicher Strasse 77 , 50937 Köln , Germany
- Institut für Materialphysik , Westfälische Wilhelms-Universität Münster , Wilhelm-Klemm-Str. 10 , 48149 Münster , Germany
| | - Carsten Busse
- II. Physikalisches Institut , Universität zu Köln , Zülpicher Strasse 77 , 50937 Köln , Germany
- Fakultät IV Physik , Universität Siegen , Walter-Flex-Str. 3 , 57072 Siegen , Germany
| | - Thomas Michely
- II. Physikalisches Institut , Universität zu Köln , Zülpicher Strasse 77 , 50937 Köln , Germany
| | - Giovanni di Santo
- Elettra Sincrotrone Trieste , Strada Statale 14 km 163.5 , 34149 Trieste , Italy
| | - Luca Petaccia
- Elettra Sincrotrone Trieste , Strada Statale 14 km 163.5 , 34149 Trieste , Italy
| | - Riichiro Saito
- Department of Physics , Tohoku University , Sendai 980-8578 , Japan
| | - Alexander Grüneis
- II. Physikalisches Institut , Universität zu Köln , Zülpicher Strasse 77 , 50937 Köln , Germany
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