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Miranda LP, da Costa DR, Peeters FM, Costa Filho RN. Vacancy clustering effect on the electronic and transport properties of bilayer graphene nanoribbons. NANOTECHNOLOGY 2022; 34:055706. [PMID: 36322965 DOI: 10.1088/1361-6528/ac9f50] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 11/01/2022] [Indexed: 06/16/2023]
Abstract
Experimental realizations of two-dimensional materials are hardly free of structural defects such as e.g. vacancies, which, in turn, modify drastically its pristine physical defect-free properties. In this work, we explore effects due to point defect clustering on the electronic and transport properties of bilayer graphene nanoribbons, for AA and AB stacking and zigzag and armchair boundaries, by means of the tight-binding approach and scattering matrix formalism. Evident vacancy concentration signatures exhibiting a maximum amplitude and an universality regardless of the system size, stacking and boundary types, in the density of states around the zero-energy level are observed. Our results are explained via the coalescence analysis of the strong sizeable vacancy clustering effect in the system and the breaking of the inversion symmetry at high vacancy densities, demonstrating a similar density of states for two equivalent degrees of concentration disorder, below and above the maximum value.
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Affiliation(s)
- L P Miranda
- Departamento de Física, Universidade Federal do Ceará, Campus do Pici, Fortaleza, Ceará, Brazil
| | - D R da Costa
- Departamento de Física, Universidade Federal do Ceará, Campus do Pici, Fortaleza, Ceará, Brazil
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education & Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China
| | - F M Peeters
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - R N Costa Filho
- Departamento de Física, Universidade Federal do Ceará, Campus do Pici, Fortaleza, Ceará, Brazil
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2
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Telychko M, Noori K, Biswas H, Dulal D, Chen Z, Lyu P, Li J, Tsai HZ, Fang H, Qiu Z, Yap ZW, Watanabe K, Taniguchi T, Wu J, Loh KP, Crommie MF, Rodin A, Lu J. Gate-Tunable Resonance State and Screening Effects for Proton-Like Atomic Charge in Graphene. NANO LETTERS 2022; 22:8422-8429. [PMID: 36214509 DOI: 10.1021/acs.nanolett.2c02235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The ability to create a robust and well-defined artificial atomic charge in graphene and understand its carrier-dependent electronic properties represents an important goal toward the development of graphene-based quantum devices. Herein, we devise a new pathway toward the atomically precise embodiment of point charges into a graphene lattice by posterior (N) ion implantation into a back-gated graphene device. The N dopant behaves as an in-plane proton-like charge manifested by formation of the characteristic resonance state in the conduction band. Scanning tunneling spectroscopy measurements at varied charge carrier densities reveal a giant energetic renormalization of the resonance state up to 220 meV with respect to the Dirac point, accompanied by the observation of gate-tunable long-range screening effects close to individual N dopants. Joint density functional theory and tight-binding calculations with modified perturbation potential corroborate experimental findings and highlight the short-range character of N-induced perturbation.
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Affiliation(s)
- Mykola Telychko
- Department of Chemistry, National University of Singapore, 117543, Singapore
| | - Keian Noori
- Institute for Functional Intelligent Materials, National University of Singapore, 117544, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 117543, Singapore
| | - Hillol Biswas
- Centre for Advanced 2D Materials, National University of Singapore, 117543, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore
| | - Dikshant Dulal
- Yale-NUS College, 16 College Avenue West, 138527, Singapore
| | - Zhaolong Chen
- Institute for Functional Intelligent Materials, National University of Singapore, 117544, Singapore
| | - Pin Lyu
- Department of Chemistry, National University of Singapore, 117543, Singapore
| | - Jing Li
- Centre for Advanced 2D Materials, National University of Singapore, 117543, Singapore
| | - Hsin-Zon Tsai
- Department of Physics, University of California, Berkeley94720, California, United States
| | - Hanyan Fang
- Department of Chemistry, National University of Singapore, 117543, Singapore
| | - Zhizhan Qiu
- Department of Chemistry, National University of Singapore, 117543, Singapore
| | - Zhun Wai Yap
- Yale-NUS College, 16 College Avenue West, 138527, Singapore
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, Japan
| | - Jing Wu
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 08-03, 2 Fusionopolis Way, Singapore138634, Singapore
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, 117543, Singapore
| | - Michael F Crommie
- Department of Physics, University of California, Berkeley94720, California, United States
| | - Aleksandr Rodin
- Centre for Advanced 2D Materials, National University of Singapore, 117543, Singapore
- Yale-NUS College, 16 College Avenue West, 138527, Singapore
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, 117543, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, 117544, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 117543, Singapore
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3
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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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Jo M, Lee JYM, Assouline A, Brasseur P, Watanabe K, Taniguchi T, Roche P, Glattli DC, Kumada N, Parmentier FD, Sim HS, Roulleau P. Scaling behavior of electron decoherence in a graphene Mach-Zehnder interferometer. Nat Commun 2022; 13:5473. [PMID: 36115841 PMCID: PMC9482640 DOI: 10.1038/s41467-022-33078-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 08/30/2022] [Indexed: 11/09/2022] Open
Abstract
AbstractOver the past 20 years, many efforts have been made to understand and control decoherence in 2D electron systems. In particular, several types of electronic interferometers have been considered in GaAs heterostructures, in order to protect the interfering electrons from decoherence. Nevertheless, it is now understood that several intrinsic decoherence sources fundamentally limit more advanced quantum manipulations. Here, we show that graphene offers a unique possibility to reach a regime where the decoherence is frozen and to study unexplored regimes of electron interferometry. We probe the decoherence of electron channels in a graphene quantum Hall PN junction, forming a Mach-Zehnder interferometer1,2, and unveil a scaling behavior of decay of the interference visibility with the temperature scaled by the interferometer length. It exhibits a remarkable crossover from an exponential decay at higher temperature to an algebraic decay at lower temperature where almost no decoherence occurs, a regime previously unobserved in GaAs interferometers.
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Zhang Y, Gao F, Gao S, Brandbyge M, He L. Characterization and Manipulation of Intervalley Scattering Induced by an Individual Monovacancy in Graphene. PHYSICAL REVIEW LETTERS 2022; 129:096402. [PMID: 36083638 DOI: 10.1103/physrevlett.129.096402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
Intervalley scattering involves microscopic processes that electrons are scattered by atomic-scale defects on the nanoscale. Although central to our understanding of electronic properties of materials, direct characterization and manipulation of range and strength of the intervalley scattering induced by an individual atomic defect have so far been elusive. Using scanning tunneling microscope, we visualize and control intervalley scattering from an individual monovacancy in graphene. By directly imaging the affected range of monovacancy-induced intervalley scattering, we demonstrate that it is inversely proportional to the energy; i.e., it is proportional to the wavelength of massless Dirac fermions. A giant electron-hole asymmetry of the intervalley scattering is observed because the monovacancy is charged. By further charging the monovacancy, the bended electronic potential around the monovacancy softens the scattering potential, which, consequently, suppresses the intervalley scattering of the monovacancy.
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Affiliation(s)
- Yu Zhang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
- Advanced Research Institute of Multidisciplinary Sciences, Beijing Institute of Technology, Beijing 100081, China
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, 100875 Beijing, China
| | - Fei Gao
- Center for Nanostructured Graphene, Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Shiwu Gao
- Beijing Computational Science Research Center, 100193 Beijing, China
| | - Mads Brandbyge
- Center for Nanostructured Graphene, Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Lin He
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, 100875 Beijing, China
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Tong LH, Tong Q, Yang LZ, Zhou YY, Wu Q, Tian Y, Zhang L, Zhang L, Qin Z, Yin LJ. Spectroscopic Visualization of Flat Bands in Magic-Angle Twisted Monolayer-Bilayer Graphene: Coexistence of Localization and Delocalization. PHYSICAL REVIEW LETTERS 2022; 128:126401. [PMID: 35394312 DOI: 10.1103/physrevlett.128.126401] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
Recent transport studies have demonstrated the great potential of twisted monolayer-bilayer graphene (TMBG) as a new platform to host moiré flat bands with a higher tunability than twisted bilayer graphene (TBG). However, a direct visualization of the flat bands in TMBG and its comparison with the ones in TBG remain unexplored. Here, via fabricating on a single sample with exactly the same twist angle of ∼1.13°, we present a direct comparative study between TMBG and TBG using scanning tunneling microscopy and spectroscopy. We observe a sharp density of states peak near the Fermi energy in tunneling spectroscopy, confirming unambiguously the existence of flat electronic bands in TMBG. The bandwidth of this flat-band peak is found to be slightly narrower than that of the TBG, validating previous theoretical predictions. Remarkably, by measuring spatially resolved spectroscopy, combined with continuum model calculation, we show that the flat-band states in TMBG exhibit a unique layer-resolved localization-delocalization coexisting feature, which offers an unprecedented possibility to utilize their cooperation on exploring novel correlation phenomena. Our work provides important microscopic insight of flat-band states for better understanding the emergent physics in graphene moiré systems.
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Affiliation(s)
- Ling-Hui Tong
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education and Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
| | - Qingjun Tong
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education and Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
| | - Li-Zhen Yang
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education and Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
| | - Yue-Ying Zhou
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education and Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
| | - Qilong Wu
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education and Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
| | - Yuan Tian
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education and Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
| | - Li Zhang
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education and Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
| | - Lijie Zhang
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education and Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
| | - Zhihui Qin
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education and Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
| | - Long-Jing Yin
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education and Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
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