1
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Rhee TG, Lam NH, Kim YG, Gu M, Hwang J, Bostwick A, Mo SK, Chun SH, Kim J, Chang YJ, Choi BK. Emergence of two distinct phase transitions in monolayer CoSe 2 on graphene. NANO CONVERGENCE 2024; 11:21. [PMID: 38789878 PMCID: PMC11126552 DOI: 10.1186/s40580-024-00427-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024]
Abstract
Dimensional modifications play a crucial role in various applications, especially in the context of device miniaturization, giving rise to novel quantum phenomena. The many-body dynamics induced by dimensional modifications, including electron-electron, electron-phonon, electron-magnon and electron-plasmon coupling, are known to significantly affect the atomic and electronic properties of the materials. By reducing the dimensionality of orthorhombic CoSe2 and forming heterostructure with bilayer graphene using molecular beam epitaxy, we unveil the emergence of two types of phase transitions through angle-resolved photoemission spectroscopy and scanning tunneling microscopy measurements. We disclose that the 2 × 1 superstructure is associated with charge density wave induced by Fermi surface nesting, characterized by a transition temperature of 340 K. Additionally, another phase transition at temperature of 160 K based on temperature dependent gap evolution are observed with renormalized electronic structure induced by electron-boson coupling. These discoveries of the electronic and atomic modifications, influenced by electron-electron and electron-boson interactions, underscore that many-body physics play significant roles in understanding low-dimensional properties of non-van der Waals Co-chalcogenides and related heterostructures.
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Affiliation(s)
- Tae Gyu Rhee
- Department of Physics, University of Seoul, Seoul, 02504, Korea
- Department of Smart Cities, University of Seoul, Seoul, 02504, Korea
| | - Nguyen Huu Lam
- Department of Physics, University of Ulsan, Ulsan, 44610, Korea
| | - Yeong Gwang Kim
- Department of Physics, University of Seoul, Seoul, 02504, Korea
- Department of Smart Cities, University of Seoul, Seoul, 02504, Korea
| | - Minseon Gu
- Department of Physics, University of Seoul, Seoul, 02504, Korea
| | - Jinwoong Hwang
- Department of Physics, Institute of Quantum Convergence Technology, Kangwon National University, Chuncheon, 24341, Korea
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Aaron Bostwick
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Seung-Hyun Chun
- Department of Physics, Sejong University, Seoul, 05006, Korea
| | - Jungdae Kim
- Department of Physics, University of Ulsan, Ulsan, 44610, Korea.
| | - Young Jun Chang
- Department of Physics, University of Seoul, Seoul, 02504, Korea.
- Department of Smart Cities, University of Seoul, Seoul, 02504, Korea.
- Department of Intelligent Semiconductor Engineering, University of Seoul, Seoul, 02504, Korea.
| | - Byoung Ki Choi
- Department of Physics, University of Seoul, Seoul, 02504, Korea.
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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2
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Gao W, Zhi G, Zhou M, Niu T. Growth of Single Crystalline 2D Materials beyond Graphene on Non-metallic Substrates. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2311317. [PMID: 38712469 DOI: 10.1002/smll.202311317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/14/2024] [Indexed: 05/08/2024]
Abstract
The advent of 2D materials has ushered in the exploration of their synthesis, characterization and application. While plenty of 2D materials have been synthesized on various metallic substrates, interfacial interaction significantly affects their intrinsic electronic properties. Additionally, the complex transfer process presents further challenges. In this context, experimental efforts are devoted to the direct growth on technologically important semiconductor/insulator substrates. This review aims to uncover the effects of substrate on the growth of 2D materials. The focus is on non-metallic substrate used for epitaxial growth and how this highlights the necessity for phase engineering and advanced characterization at atomic scale. Special attention is paid to monoelemental 2D structures with topological properties. The conclusion is drawn through a discussion of the requirements for integrating 2D materials with current semiconductor-based technology and the unique properties of heterostructures based on 2D materials. Overall, this review describes how 2D materials can be fabricated directly on non-metallic substrates and the exploration of growth mechanism at atomic scale.
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Affiliation(s)
- Wenjin Gao
- Tianmushan Laboratory, Hangzhou, 310023, China
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
| | | | - Miao Zhou
- Tianmushan Laboratory, Hangzhou, 310023, China
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
| | - Tianchao Niu
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
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3
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Hwang J, Ruan W, Chen Y, Tang S, Crommie MF, Shen ZX, Mo SK. Charge density waves in two-dimensional transition metal dichalcogenides. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:044502. [PMID: 38518359 DOI: 10.1088/1361-6633/ad36d3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 03/22/2024] [Indexed: 03/24/2024]
Abstract
Charge density wave (CDW is one of the most ubiquitous electronic orders in quantum materials. While the essential ingredients of CDW order have been extensively studied, a comprehensive microscopic understanding is yet to be reached. Recent research efforts on the CDW phenomena in two-dimensional (2D) materials provide a new pathway toward a deeper understanding of its complexity. This review provides an overview of the CDW orders in 2D with atomically thin transition metal dichalcogenides (TMDCs) as the materials platform. We mainly focus on the electronic structure investigations on the epitaxially grown TMDC samples with angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy as complementary experimental tools. We discuss the possible origins of the 2D CDW, novel quantum states coexisting with them, and exotic types of charge orders that can only be realized in the 2D limit.
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Affiliation(s)
- Jinwoong Hwang
- Department of Physics and Institute of Quantum Convergence Technology, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Wei Ruan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200438, People's Republic of China
| | - Yi Chen
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing 100871, People's Republic of China
| | - Shujie Tang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Michael F Crommie
- Department of Physics, University of California, Berkeley, CA, United States of America
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States of America
- Kavli Energy NanoSciences Institute at the University of California at Berkeley, Berkeley, CA 94720, United States of America
| | - Zhi-Xun Shen
- Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA, United States of America
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, United States of America
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 United States of America
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4
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Coelho PM. Magnetic doping in transition metal dichalcogenides. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:203001. [PMID: 38324890 DOI: 10.1088/1361-648x/ad271b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 02/07/2024] [Indexed: 02/09/2024]
Abstract
Transition metal dichalcogenides (TMDCs) are materials with unique electronic properties due to their two-dimensional nature. Recently, there is a large and growing interest in synthesizing ferromagnetic TMDCs for applications in electronic devices and spintronics. Apart from intrinsically magnetic examples, modification via either intrinsic defects or external dopants may induce ferromagnetism in non-magnetic TMDCs and, hence expand the application of these materials. Here, we review recent experimental work on intrinsically non-magnetic TMDCs that present ferromagnetism as a consequence of either intrinsic defects or doping via self-flux approach, ion implantation or e-beam evaporation. The experimental work discussed here is organized by modification/doping mechanism. We also review current work on density functional theory calculations that predict ferromagnetism in doped systems, which also serve as preliminary data for the choice of new doped TMDCs to be explored experimentally. Implementing a controlled process to induce magnetism in two-dimensional materials is key for technological development and this topical review discusses the fundamental procedures while presenting promising materials to be investigated in order to achieve this goal.
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Affiliation(s)
- Paula Mariel Coelho
- Department of Physics, University of North Florida, Jacksonville, FL, United States of America
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5
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Zhao WM, Ding W, Wang QW, Meng YX, Zhu L, Jia ZY, Zhu W, Li SC. Observation of Electronic Strong Correlation in VTe_{2}-2sqrt[3]×2sqrt[3] Monolayer. PHYSICAL REVIEW LETTERS 2023; 131:086501. [PMID: 37683154 DOI: 10.1103/physrevlett.131.086501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 07/09/2023] [Accepted: 07/18/2023] [Indexed: 09/10/2023]
Abstract
Strong electron correlation under two-dimensional limit is intensely studied in the transition metal dichalcogenides monolayers, mostly within their charge density wave (CDW) states that host a star of David period. Here, by using scanning tunneling microscopy and spectroscopy and density functional theory calculations with on-site Hubbard corrections, we study the VTe_{2} monolayer with a different 2sqrt[3]×2sqrt[3] CDW period. We find that the dimerization of neighboring Te-Te and V-V atoms occurs during the CDW transition, and that the strong correlation effect opens a Mott-like full gap at Fermi energy (E_{F}). We further demonstrate that such a Mott phenomenon is ascribed to the combination of the CDW transition and on-site Coulomb interactions. Our work provides a new platform for exploring Mott physics in 2D materials.
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Affiliation(s)
- Wei-Min Zhao
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Wenjun Ding
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Research Center for Physical Sciences at the Microscale, Department of Physics, University of Science and Technology of China, Hefei 230026, China
| | - Qi-Wei Wang
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Yu-Xin Meng
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Li Zhu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Zhen-Yu Jia
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Wenguang Zhu
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Research Center for Physical Sciences at the Microscale, Department of Physics, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, Hefei 230088, China
| | - Shao-Chun Li
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
- Hefei National Laboratory, Hefei 230088, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory for Nanotechnology, Nanjing University, Nanjing 210093, China
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6
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Zong J, Dong ZY, Huang J, Wang K, Wang QW, Meng Q, Tian Q, Qiu X, Mu Y, Wang L, Ren W, Xie X, Chen W, Zhang Y, Wang C, Li FS, Li SC, Li JX, Yuan H, Zhang Y. Inducing itinerant ferromagnetism by manipulating van Hove singularity in epitaxial monolayer 1T-VSe 2. Sci Bull (Beijing) 2023; 68:990-997. [PMID: 37100643 DOI: 10.1016/j.scib.2023.04.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 03/16/2023] [Accepted: 04/06/2023] [Indexed: 04/28/2023]
Abstract
The itinerant ferromagnetism can be induced by a van Hove singularity (VHS) with a divergent density of states at Fermi level. Utilizing the giant magnified dielectric constant εr of SrTiO3(111) substrate with cooling, here we successfully manipulated the VHS in the epitaxial monolayer (ML) 1T-VSe2 film approaching to Fermi level via the large interfacial charge transfer, and thus induced a two-dimensional (2D) itinerant ferromagnetic state below 3.3 K. Combining the direct characterization of the VHS structure via angle-resolved photoemission spectroscopy (ARPES), together with the theoretical analysis, we ascribe the manipulation of VHS to the physical origin of the itinerant ferromagnetic state in ML 1T-VSe2. Therefore, we further demonstrated that the ferromagnetic state in the 2D system can be controlled through manipulating the VHS by engineering the film thickness or replacing the substrate. Our findings clearly evidence that the VHS can serve as an effective manipulating degree of freedom for the itinerant ferromagnetic state, expanding the application potentials of 2D magnets for the next-generation information technology.
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Affiliation(s)
- Junyu Zong
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Zhao-Yang Dong
- Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Junwei Huang
- College of Engineering and Applied Sciences and National Laboratory of Solid-State Microstructures, Nanjing University, Nanjing 210093, China
| | - Kaili Wang
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Qi-Wei Wang
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Qinghao Meng
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Qichao Tian
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Xiaodong Qiu
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Yuyang Mu
- National Laboratory of Solid-State Microstructures, 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, Suzhou 215123, China
| | - Wei Ren
- Vacuum Interconnected NanoTech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, China
| | - Xuedong Xie
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Wang Chen
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Yongheng Zhang
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Can Wang
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Fang-Sen Li
- Vacuum Interconnected NanoTech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, China
| | - Shao-Chun Li
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jian-Xin Li
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
| | - Hongtao Yuan
- College of Engineering and Applied Sciences and National Laboratory of Solid-State Microstructures, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
| | - Yi Zhang
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
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7
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Wines D, Tiihonen J, Saritas K, Krogel JT, Ataca C. A Quantum Monte Carlo Study of the Structural, Energetic, and Magnetic Properties of Two-Dimensional H and T Phase VSe 2. J Phys Chem Lett 2023; 14:3553-3560. [PMID: 37017431 DOI: 10.1021/acs.jpclett.3c00497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Previous works have controversially claimed near-room-temperature ferromagnetism in two-dimensional (2D) VSe2, with conflicting results throughout the literature. These discrepancies in magnetic properties between both phases (T and H) of 2D VSe2 are most likely due to the structural parameters being coupled to the magnetic properties. Specifically, both phases have a close lattice match and similar total energies, which makes it difficult to determine which phase is being observed experimentally. In this study, we used a combination of density functional theory, highly accurate diffusion Monte Carlo (DMC), and a surrogate Hessian line-search optimization technique to resolve the previously reported discrepancy in structural parameters and relative phase stability. With DMC accuracy, we determined the free-standing geometry of both phases and constructed a phase diagram. Our findings demonstrate the successes of the DMC method coupled with the surrogate Hessian structural optimization technique when applied to a 2D magnetic system.
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Affiliation(s)
- Daniel Wines
- Materials Science and Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Juha Tiihonen
- Department of Physics, Nanoscience Center, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
| | - Kayahan Saritas
- Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jaron T Krogel
- Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Can Ataca
- Department of Physics, University of Maryland Baltimore County, Baltimore, Maryland 21250, United States
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8
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Bai Y, Jian T, Pan Z, Deng J, Lin X, Zhu C, Huo D, Cheng Z, Liu Y, Cui P, Zhang Z, Zou Q, Zhang C. Realization of Multiple Charge-Density Waves in NbTe 2 at the Monolayer Limit. NANO LETTERS 2023; 23:2107-2113. [PMID: 36881543 DOI: 10.1021/acs.nanolett.2c04306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Layered transition-metal dichalcogenides down to the monolayer (ML) limit provide a fertile platform for exploring charge-density waves (CDWs). Here, we experimentally unveil the richness of the CDW phases in ML-NbTe2 for the first time. Not only the theoretically predicted 4 × 4 and 4 × 1 phases but also two unexpected 28×28 and 19×19 phases are realized. For such a complex CDW system, we establish an exhaustive growth phase diagram via systematic efforts in the material synthesis and scanning tunneling microscope characterization. Moreover, the energetically stable phase is the larger-scale order (19×19), which is surprisingly in contradiction to the prior prediction (4 × 4). These findings are confirmed using two different kinetic pathways: i.e., direct growth at proper growth temperatures (T) and low-T growth followed by high-T annealing. Our results provide a comprehensive diagram of the "zoo" of CDW orders in ML-NbTe2.
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Affiliation(s)
- Yusong Bai
- School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Tao Jian
- School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
- Wuhan Institute of Quantum Technology, Wuhan 430206, People's Republic of China
| | - Zemin Pan
- School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Jinghao Deng
- School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Xiaoyu Lin
- School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Chao Zhu
- School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Da Huo
- School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Zhengbo Cheng
- School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Yong Liu
- School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Ping Cui
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Zhenyu Zhang
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Qiang Zou
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Chendong Zhang
- School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
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9
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Mi K, Guo Y. Magnetism in curved VSe 2 monolayers. RSC Adv 2023; 13:8307-8316. [PMID: 36926003 PMCID: PMC10012335 DOI: 10.1039/d3ra01319g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 03/06/2023] [Indexed: 03/18/2023] Open
Abstract
Our extensive first-principles calculations on magnetic VSe2 monolayers reveal the curvature-induced periodic fluctuation in the magnetic moments of V atoms and the occurrence of charge density waves for curved VSe2 monolayers. The bending energies of curved 2H-VSe2 monolayers increase with increasing curvature but that of curved 1T-VSe2 monolayers with curvature is not monotonic. The significant periodic magnetic orders in curved VSe2 monolayers can be attributed to the curvature-induced modification of V-Se bond structure and periodic length variations in V-Se bonds. A phenomenological model is established to describe the relation of the total magnetic moment in one period of a curved VSe2 monolayer with its curvature radius and the number of hexagonal rings that forms one period. These results unveil the effect of bending deformation on magnetic van der Waals monolayers and provide a possible way to develop functional magnetic devices by mechanical design.
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Affiliation(s)
- Kexin Mi
- State Key Laboratory of Mechanics and Control of Mechanical Structures, MOE Key Laboratory for Intelligent Nano Materials and Devices, College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics Nanjing 210016 China
| | - Yufeng Guo
- State Key Laboratory of Mechanics and Control of Mechanical Structures, MOE Key Laboratory for Intelligent Nano Materials and Devices, College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics Nanjing 210016 China
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10
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Fumega AO, Diego J, Pardo V, Blanco-Canosa S, Errea I. Anharmonicity Reveals the Tunability of the Charge Density Wave Orders in Monolayer VSe 2. NANO LETTERS 2023; 23:1794-1800. [PMID: 36825982 PMCID: PMC9999451 DOI: 10.1021/acs.nanolett.2c04584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 02/22/2023] [Indexed: 06/18/2023]
Abstract
VSe2 is a layered compound that has attracted great attention due to its proximity to a ferromagnetic state that is quenched by its charge density wave (CDW) phase. In the monolayer limit, unrelated experiments have reported different CDW orders with different transition temperatures, making this monolayer very controversial. Here we perform first-principles nonperturbative anharmonic phonon calculations in monolayer VSe2 in order to estimate the CDW order and the corresponding transition temperature. They reveal that monolayer VSe2 develops two independent charge density wave orders that compete as a function of strain. Variations of only 1.5% in the lattice parameter are enough to stabilize one order or the other. Moreover, we analyze the impact of external Lennard-Jones interactions, showing that these can act together with anharmonicity to suppress the CDW orders. Our results solve previous experimental contradictions, highlighting the high tunability and substrate dependency of the CDW orders of monolayer VSe2.
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Affiliation(s)
| | - Josu Diego
- Fisika
Aplikatua Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU), 20018 San Sebastián, Spain
- Centro
de Física de Materiales (CSIC-UPV/EHU), 20018 San Sebastián, Spain
| | - Victor Pardo
- Departamento
de Física Aplicada, Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Spain
- Instituto
de Materiais iMATUS, Universidade de Santiago
de Compostela, 15782 Santiago de Compostela, Spain
| | - Santiago Blanco-Canosa
- Donostia
International Physics Center (DIPC), 20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation
for Science, 48013 Bilbao, Spain
| | - Ion Errea
- Fisika
Aplikatua Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU), 20018 San Sebastián, Spain
- Centro
de Física de Materiales (CSIC-UPV/EHU), 20018 San Sebastián, Spain
- Donostia
International Physics Center (DIPC), 20018 San Sebastián, Spain
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11
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Wu Y, Li J, Liu Y. Two-dimensional chalcogenide-based ferromagnetic semiconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 35:083002. [PMID: 36540916 DOI: 10.1088/1361-648x/acaa7e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 12/09/2022] [Indexed: 06/17/2023]
Abstract
Two-dimensional (2D) magnetic materials draw an enormous amount of attention due to their novel physical properties and potential spintronics device applications. Room-temperature ferromagnetic (FM) semiconductors have long been pursued in 2D magnetic materials, which show a long range magnetic order down to atomic-layer thickness. The intrinsic ferromagnetism has been predicted in a series of 2D materials and verified in experiments and the magnetism can be modulated by multiple physical fields, exhibiting promising application prospects. In this review, we overview several types of 2D chalcogenide-based FM semiconductors discovered in recent years. We summary and compare their basic physical properties, including the crystal structures, electronic structures, and mechanical stability. The 2D magnetism can be described by several physical models. We also focus on the recent progresses about theoretical prediction of FM semiconductors and experimental observation of external-field regulation. Most of investigations have shown that 2D chalcogenide-based FM semiconductors have relatively high Curie temperature (Tc) and structural stability. These materials are promising to realize the room-temperature ferromagnetism in atomic-layer thickness, which is significant to design spintronics devices.
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Affiliation(s)
- Yanling Wu
- State Key Laboratory of Metastable Materials Science and Technology & Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, People's Republic of China
| | - Jun Li
- State Key Laboratory of Metastable Materials Science and Technology & Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, People's Republic of China
| | - Yong Liu
- State Key Laboratory of Metastable Materials Science and Technology & Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, People's Republic of China
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12
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Firouzeh S, Rahman MW, Pramanik S. Thermally-driven large current-perpendicular-to-plane magnetoresistance in ultrathin flakes of vanadium diselenide. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:495802. [PMID: 36240752 DOI: 10.1088/1361-648x/ac9a94] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 10/14/2022] [Indexed: 06/16/2023]
Abstract
Current-perpendicular-to-plane magnetoresistance (CPP MR) in layered heterojunctions is at the heart of modern magnetic field sensing and data storage technologies. van der waals heterostructures and two-dimensional (2D) magnets opened a new playground for exploring this effect, although most 2D magnets exhibit large CPP MR only at very low temperatures due to their very low Curie temperatures. vanadium diselenide (VSe2) is a promising material since its monolayers can potentially act as room temperature ferromagnets. VSe2multilayers have been predicted to exhibit CPP MR effects, although experimental work in this area remains scarce. In this work we investigate CPP MR in 1T-VSe2ultrathin flakes, revealing alarge (∼60%-70%), positive, linear, and non saturating CPP MR, which persists close to room temperature (∼250 K), in a relatively small magnetic field range of ±12 kG. The CPP MR has been found to increase with decreasing flake thickness. The CPP MR originates due to the intrinsic inhomogeneity in the CPP transport path, andexhibits unprecedented immunity against thermal fluctuations, leading to increasingly enhanced MR as temperature is increased, even significantly beyond the charge density wave transition temperature. The observed 'thermally-driven' MR features are remarkably robust and reproducible, and can offer a viable route for developing practical room temperature 2D based magnetic sensor technologies. Our results also suggest that harnessing similar effects in other 2D systems could result in large MR as well, thereby motivating further research on CPP transport in these systems, which has been relatively unexplored so far.
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Affiliation(s)
- Seyedamin Firouzeh
- Electrical and Computer Engineering, University of Alberta, Room- W3-075, ECERF Building, Edmonton, Alberta T6G 2R3, Canada
| | - Md Wazedur Rahman
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Sandipan Pramanik
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
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13
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Goodwin ZAH, Fal'ko VI. Moiré modulation of charge density waves. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:494001. [PMID: 36223792 DOI: 10.1088/1361-648x/ac99ca] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 10/12/2022] [Indexed: 06/16/2023]
Abstract
Here we investigate how charge density waves (CDWs), inherent to a monolayer, are effected by creating twisted van der Waals structures. Homobilayers of metallic transition metal dichalcogenides (TMDs), at small twist angles where there is significant atomic reconstruction, are utilised as an example to investigate the interplay between the moiré domain structure and CDWs of different periods. For3×3CDWs, there is no geometric constraint to prevent the CDWs from propagating throughout the moiré structure. Whereas for2×2CDWs, to ensure the CDWs in each layer have the most favourable interactions in the domains, the CDW phase must be destroyed in the connecting domain walls. For3×3CDWs with twist angles close to 180∘, moiré-scale triangular structures can form; while close to 0∘, moiré-scale dimer domains occur. The star-of-David CDW (13×13) is found to host CDWs in the domains only, since there is one low energy stacking configuration, similar to the2×2CDWs. These predictions are offered for experimental verification in twisted bilayer metallic TMDs which host CDWs, and we hope this will stimulate further research on the interplay between the moiré superlattice and CDW phases intrinsic to the comprising 2D materials.
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Affiliation(s)
- Zachary A H Goodwin
- National Graphene Institute, University of Manchester, Booth St. E., Manchester M13 9PL, United Kingdom
- School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Vladimir I Fal'ko
- National Graphene Institute, University of Manchester, Booth St. E., Manchester M13 9PL, United Kingdom
- School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- Henry Royce Institute for Advanced Materials, University of Manchester, Manchester M13 9PL, United Kingdom
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14
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Wang Z, Wang Z, Feng YP, Loh KP. Probing the Origin of Chiral Charge Density Waves in the Two-Dimensional Limits. NANO LETTERS 2022; 22:7615-7620. [PMID: 36099590 DOI: 10.1021/acs.nanolett.2c02723] [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
Chirality generates spontaneous symmetry breaking and profoundly influences the topology, charge, and spin orders of materials. The chiral charge density wave (CDW) exhibits macroscopic chirality in the achiral crystal during the spontaneous electronic phase transitions. However, the mechanism of chiral CDW formation is shrouded in controversy. In this work, we report that two-dimensional H-phase TaS2 synthesized by molecular-beam epitaxy (MBE) shows a predominantly chiral CDW phase. Scanning tunneling microscopy (STM) imaging of the CDW reconstruction spots reveals a clockwise or anticlockwise intensity variation along the STM-imaged spots. First-principles calculations further show that the rotational symmetry of the momentum-dependent electron-phonon coupling is broken, giving rise to chirality. Our work provides new insights into the physical origin of the chiral charge-ordered states, shedding light on a general ordering rule in chiral CDWs.
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Affiliation(s)
- Ziying Wang
- SZU-NUS Collaborative Innovation Centre for Optoelectronic Science & Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, China 518060
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
| | - Zishen Wang
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Yuan Ping Feng
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Kian Ping Loh
- SZU-NUS Collaborative Innovation Centre for Optoelectronic Science & Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, China 518060
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
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15
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Zhu Y, Gao Y, Jiang X, Zhao J. Effects of vacancy defects on the magnetic properties of vanadium diselenide monolayers: a first principle investigation. Phys Chem Chem Phys 2022; 24:17615-17622. [PMID: 35833467 DOI: 10.1039/d2cp01537d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Long-range ferromagnetic (FM) order in vanadium diselenide (VSe2) monolayers (MLs) remains a controversial subject. In this theoretical study, we examined the effect of vacancy defects on the magnetic properties of octahedrally coordinated 1T-VSe2 MLs using spin-polarized density functional theory (DFT). In total, 45 different kinds of defects with various concentrations were introduced, including two single vacancies (S), 27 double vacancies (D), nine triple vacancies (T), and seven quadruple vacancies (Q). To understand the magnetic properties, SSe, DSe-(10), TSe-(10)(10), and QSe-(21)(10)(10) were selected to be analyzed because they had low formation energies and large variations in magnetic moments (M). Compared with the perfect VSe2 ML, the values of the M of vanadium (V) decreased from 0.675 to 0.466, 0.183, 0.213, and 0.208 μB with increasing vacancy concentration. The same trend was also found for the energy differences between FM and antiferromagnetic (AFM) ordering. These results generally indicated weaker FM coupling and a lower Curie temperature in defective VSe2. Vacancy-induced lattice distortion, d orbital shifting, electronic occupation, and spin density redistribution were discussed in order to explain the above observations. Our investigation demonstrated a strong dependence of M and the magnetic interaction of VSe2 on the concentration and types of Se vacancies, which would explain the uncertainties encountered in magnetic experiments.
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Affiliation(s)
- Yan Zhu
- Key Laboratory of Material Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, China.
| | - Yinlu Gao
- Key Laboratory of Material Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, China.
| | - Xue Jiang
- Key Laboratory of Material Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, China.
| | - Jijun Zhao
- Key Laboratory of Material Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, China.
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16
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Göhler F, Ramasubramanian S, Rajak SK, Rösch N, Schütze A, Wolff S, Cordova DLM, Johnson DC, Seyller T. Modulation doping and charge density wave transition in layered PbSe-VSe 2 ferecrystal heterostructures. NANOSCALE 2022; 14:10143-10154. [PMID: 35796182 DOI: 10.1039/d2nr01071b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Controlling charge carrier concentrations remains a major challenge in the application of quasi-two-dimensional materials. A promising approach is the modulation doping of transport channels via charge transfer from neighboring layers in stacked heterostructures. Ferecrystals, which are metastable layered structures created from artificial elemental precursors, are a perfect model system to investigate modulation doping, as they offer unparalleled freedom in the combination of different constituents and variable layering sequences. In this work, differently stacked combinations of rock-salt structured PbSe and VSe2 were investigated using X-ray photoelectron spectroscopy. The PbSe layers act as electron donors in all heterostructures, with about 0.1 to 0.3 donated electrons per VSe2 unit cell. While they initially retain their inherent semiconducting behavior, they themselves become metallic when combined with a larger number of VSe2 layers, as evidenced by a change of the XPS core level lineshape. Additional analysis of the valence band structure was performed for selected stacking orders at different sample temperatures to investigate a predicted charge density wave (CDW) transition. While there appear to be hints of a gap opening, the data so far is inconclusive and the application of spatially resolved techniques such as scanning tunneling microscopy is encouraged for further studies.
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Affiliation(s)
- Fabian Göhler
- Institute of Physics, Chemnitz University of Technology, 09126 Chemnitz, Germany.
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), 09126 Chemnitz, Germany
| | | | - Sanam Kumari Rajak
- Institute of Physics, Chemnitz University of Technology, 09126 Chemnitz, Germany.
| | - Niels Rösch
- Institute of Physics, Chemnitz University of Technology, 09126 Chemnitz, Germany.
| | - Adrian Schütze
- Institute of Physics, Chemnitz University of Technology, 09126 Chemnitz, Germany.
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), 09126 Chemnitz, Germany
| | - Susanne Wolff
- Institute of Physics, Chemnitz University of Technology, 09126 Chemnitz, Germany.
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), 09126 Chemnitz, Germany
| | | | - David C Johnson
- Department of Chemistry, University of Oregon, Eugene, Oregon 97401, USA
| | - Thomas Seyller
- Institute of Physics, Chemnitz University of Technology, 09126 Chemnitz, Germany.
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), 09126 Chemnitz, Germany
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17
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Tayran C, Çakmak M. Charge density wave in a SnSe 2 layer on and the effect of surface hydrogenation. Phys Chem Chem Phys 2022; 24:6820-6827. [PMID: 35244640 DOI: 10.1039/d1cp05569k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have carried out an investigation using density functional theory (DFT) of the atomic and electronic structures of SnSe2 layers on the surface and hydrogenation of this surface. We have considered a (2 × 2) SnSe2 superstructure oriented along the diagonal direction of the surface periodicity, for which scanning tunneling microscopy (STM) measurements have recently been reported. In the band structure calculations, while the s-p character surface state originating from each SnSe2 layer is determined, there is an additional half-filled surface state in the fundamental band gap region due to the Sn adatom. At the M̄ point in the Brillouin zone, a charge density wave (CDW) partial gap opening of ∼0.1 eV occurs between these surface states close to the Fermi level. Here, the CDW gap is caused by two reasons; (i) Fermi surface nesting, due to the inequivalent electron pockets at the M̄ point, and (ii) the out of plane weak electron-phonon coupling regime due to the mean-field (MF) theory (2Δ/kBTMF = 3.52). Upon hydrogen adsorption on the surface, we have obtained a β-phase SnSe layer and SeH2 molecule with a bond angle of ∼90°. The hydrogenated surface pushes the surface state associated with the SnSe2 layer into the Si projected bulk band continuum. After SeH2 desorption, the work function drops from 5.20 eV to 4.39 eV.
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Affiliation(s)
- C Tayran
- Department of Physics, Gazi University, Ankara, Turkey.
| | - M Çakmak
- Department of Photonics, Faculty of Applied Sciences, Gazi University, Ankara, Turkey. .,Photonics Application and Research Center, Gazi University, Ankara, Turkey
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18
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Ganguli SC, Vaňo V, Kezilebieke S, Lado JL, Liljeroth P. Confinement-Engineered Superconductor to Correlated-Insulator Transition in a van der Waals Monolayer. NANO LETTERS 2022; 22:1845-1850. [PMID: 35167310 PMCID: PMC8915256 DOI: 10.1021/acs.nanolett.1c03491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 02/10/2022] [Indexed: 06/14/2023]
Abstract
Transition metal dichalcogenides (TMDC) are a rich family of two-dimensional materials displaying a multitude of different quantum ground states. In particular, d3 TMDCs are paradigmatic materials hosting a variety of symmetry broken states, including charge density waves, superconductivity, and magnetism. Among this family, NbSe2 is one of the best-studied superconducting materials down to the monolayer limit. Despite its superconducting nature, a variety of results point toward strong electronic repulsions in NbSe2. Here, we control the strength of the interactions experimentally via quantum confinement and use low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) to demonstrate that NbSe2 is in close proximity to a correlated insulating state. This reveals the coexistence of competing interactions in NbSe2, creating a transition from a superconducting to an insulating quantum correlated state by confinement-controlled interactions. Our results demonstrate the dramatic role of interactions in NbSe2, establishing NbSe2 as a correlated superconductor with competing interactions.
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19
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Large-gap insulating dimer ground state in monolayer IrTe 2. Nat Commun 2022; 13:906. [PMID: 35173153 PMCID: PMC8850425 DOI: 10.1038/s41467-022-28542-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 02/01/2022] [Indexed: 11/09/2022] Open
Abstract
Monolayers of two-dimensional van der Waals materials exhibit novel electronic phases distinct from their bulk due to the symmetry breaking and reduced screening in the absence of the interlayer coupling. In this work, we combine angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy to demonstrate the emergence of a unique insulating 2 × 1 dimer ground state in monolayer 1T-IrTe2 that has a large band gap in contrast to the metallic bilayer-to-bulk forms of this material. First-principles calculations reveal that phonon and charge instabilities as well as local bond formation collectively enhance and stabilize a charge-ordered ground state. Our findings provide important insights into the subtle balance of interactions having similar energy scales that occurs in the absence of strong interlayer coupling, which offers new opportunities to engineer the properties of 2D monolayers.
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20
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Chua R, Henke J, Saha S, Huang Y, Gou J, He X, Das T, van Wezel J, Soumyanarayanan A, Wee ATS. Coexisting Charge-Ordered States with Distinct Driving Mechanisms in Monolayer VSe 2. ACS NANO 2022; 16:783-791. [PMID: 34931805 DOI: 10.1021/acsnano.1c08304] [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
Thinning crystalline materials to two dimensions (2D) creates a rich playground for electronic phases, including charge, spin, superconducting, and topological order. Bulk materials hosting charge density waves (CDWs), when reduced to ultrathin films, have shown CDW enhancement and tunability. However, charge order confined to only 2D remains elusive. Here we report a distinct charge ordered state emerging in the monolayer limit of 1T-VSe2. Systematic scanning tunneling microscopy experiments reveal that bilayer VSe2 largely retains the bulk electronic structure, hosting a tridirectional CDW. However, monolayer VSe2 ─consistently across distinct substrates─exhibits a dimensional crossover, hosting two CDWs with distinct wavelengths and transition temperatures. Electronic structure calculations reveal that while one CDW is bulk-like and arises from the well-known Peierls mechanism, the other is decidedly unconventional. The observed CDW-lattice decoupling and the emergence of a flat band suggest that the second CDW could arise from enhanced electron-electron interactions in the 2D limit. These findings establish monolayer-VSe2 as a host of coexisting charge orders with distinct origins, and enable the tailoring of electronic phenomena via emergent interactions in 2D materials.
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Affiliation(s)
- Rebekah Chua
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Jans Henke
- Institute for Theoretical Physics Amsterdam and Delta Institute for Theoretical Physics, University of Amsterdam, Amsterdam 1098XH, The Netherlands
| | - Surabhi Saha
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Yuli Huang
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Joint School of National University of Singapore and Tianjin University, Binhai New City, Fuzhou 350207, China
| | - Jian Gou
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Xiaoyue He
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Tanmoy Das
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Jasper van Wezel
- Institute for Theoretical Physics Amsterdam and Delta Institute for Theoretical Physics, University of Amsterdam, Amsterdam 1098XH, The Netherlands
| | - Anjan Soumyanarayanan
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Institute of Materials Research & Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), Singapore 138634, Singapore
| | - Andrew T S Wee
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
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21
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Ren MQ, Han S, Fan JQ, Wang L, Wang P, Ren W, Peng K, Li S, Wang SZ, Zheng FW, Zhang P, Li F, Ma X, Xue QK, Song CL. Semiconductor-Metal Phase Transition and Emergent Charge Density Waves in 1 T-ZrX 2 (X = Se, Te) at the Two-Dimensional Limit. NANO LETTERS 2022; 22:476-484. [PMID: 34978815 DOI: 10.1021/acs.nanolett.1c04372] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A charge density wave (CDW) is a collective quantum phenomenon in metals and features a wavelike modulation of the conduction electron density. A microscopic understanding and experimental control of this many-body electronic state in atomically thin materials remain hot topics in materials physics. By means of material engineering, we realized a dimensionality and Zr intercalation induced semiconductor-metal phase transition in 1T-ZrX2 (X = Se, Te) ultrathin films, accompanied by a commensurate 2 × 2 CDW order. Furthermore, we observed a CDW energy gap of up to 22 meV around the Fermi level. Fourier-transformed scanning tunneling microscopy and angle-resolved photoemission spectroscopy reveal that 1T-ZrX2 films exhibit the simplest Fermi surface among the known CDW materials in TMDCs, consisting only of a Zr 4d derived elliptical electron conduction band at the corners of the Brillouin zone.
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Affiliation(s)
- Ming-Qiang Ren
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Sha Han
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Jia-Qi Fan
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Li Wang
- Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Pengdong Wang
- Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Wei Ren
- Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Kun Peng
- Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Shujing Li
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
| | - Shu-Ze Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Fa-Wei Zheng
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, People's Republic of China
| | - Ping Zhang
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
| | - Fangsen Li
- Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Xucun Ma
- State Key Laboratory of Low-Dimensional Quantum Physics, 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
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, 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 Academy of Quantum Information Sciences, Beijing 100193, People's Republic of China
| | - Can-Li Song
- State Key Laboratory of Low-Dimensional Quantum Physics, 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
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22
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van Efferen C, Berges J, Hall J, van Loon E, Kraus S, Schobert A, Wekking T, Huttmann F, Plaar E, Rothenbach N, Ollefs K, Arruda LM, Brookes N, Schönhoff G, Kummer K, Wende H, Wehling T, Michely T. A full gap above the Fermi level: the charge density wave of monolayer VS 2. Nat Commun 2021; 12:6837. [PMID: 34824213 PMCID: PMC8617271 DOI: 10.1038/s41467-021-27094-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 11/04/2021] [Indexed: 11/09/2022] Open
Abstract
In the standard model of charge density wave (CDW) transitions, the displacement along a single phonon mode lowers the total electronic energy by creating a gap at the Fermi level, making the CDW a metal-insulator transition. Here, using scanning tunneling microscopy and spectroscopy and ab initio calculations, we show that VS2 realizes a CDW which stands out of this standard model. There is a full CDW gap residing in the unoccupied states of monolayer VS2. At the Fermi level, the CDW induces a topological metal-metal (Lifshitz) transition. Non-linear coupling of transverse and longitudinal phonons is essential for the formation of the CDW and the full gap above the Fermi level. Additionally, x-ray magnetic circular dichroism reveals the absence of net magnetization in this phase, pointing to coexisting charge and spin density waves in the ground state.
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Affiliation(s)
- Camiel van Efferen
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937, Köln, Germany.
| | - Jan Berges
- Institut für Theoretische Physik, Bremen Center for Computational Materials Science, and MAPEX Center for Materials and Processes, Universität Bremen, Otto-Hahn-Allee 1, 28359, Bremen, Germany
| | - Joshua Hall
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937, Köln, Germany
| | - Erik van Loon
- Institut für Theoretische Physik, Bremen Center for Computational Materials Science, and MAPEX Center for Materials and Processes, Universität Bremen, Otto-Hahn-Allee 1, 28359, Bremen, Germany
| | - Stefan Kraus
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937, Köln, Germany
| | - Arne Schobert
- Institut für Theoretische Physik, Bremen Center for Computational Materials Science, and MAPEX Center for Materials and Processes, Universität Bremen, Otto-Hahn-Allee 1, 28359, Bremen, Germany
| | - Tobias Wekking
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937, Köln, Germany
| | - Felix Huttmann
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937, Köln, Germany
| | - Eline Plaar
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937, Köln, Germany
| | - Nico Rothenbach
- Fakultät für Physik und Center für Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Carl-Benz-Straße, 47057, Duisburg, Germany
| | - Katharina Ollefs
- Fakultät für Physik und Center für Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Carl-Benz-Straße, 47057, Duisburg, Germany
| | - Lucas Machado Arruda
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Nick Brookes
- European Synchrotron Research Facility (ESRF), Avenue des Martyrs 71, CS 40220, 38043, Grenoble Cedex 9, France
| | - Gunnar Schönhoff
- Institut für Theoretische Physik, Bremen Center for Computational Materials Science, and MAPEX Center for Materials and Processes, Universität Bremen, Otto-Hahn-Allee 1, 28359, Bremen, Germany
| | - Kurt Kummer
- European Synchrotron Research Facility (ESRF), Avenue des Martyrs 71, CS 40220, 38043, Grenoble Cedex 9, France
| | - Heiko Wende
- Fakultät für Physik und Center für Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Carl-Benz-Straße, 47057, Duisburg, Germany
| | - Tim Wehling
- Institut für Theoretische Physik, Bremen Center for Computational Materials Science, and MAPEX Center for Materials and Processes, Universität Bremen, Otto-Hahn-Allee 1, 28359, Bremen, Germany
- Institute of Theoretical Physics, Universität Hamburg, Notkestraße 9-11, 22607, Hamburg, Germany
| | - Thomas Michely
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937, Köln, Germany
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23
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Li S, Zhang Z, Xu C, Liu Z, Chen X, Bian Q, Gedeon H, Shao Z, Liu L, Liu Z, Kang N, Cheng HM, Ren W, Pan M. Magnetic Doping Induced Superconductivity-to-Incommensurate Density Waves Transition in a 2D Ultrathin Cr-Doped Mo 2C Crystal. ACS NANO 2021; 15:14938-14946. [PMID: 34469117 DOI: 10.1021/acsnano.1c05133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In the vicinity of a competing electronic order, superconductivity emerges within a superconducting dome in the phase diagram, which has been demonstrated in unconventional superconductors and transition-metal dichalcogenides (TMDs), suggesting a scenario where fluctuations or a partial melting of a parent order are essential for inducing superconductivity. Here, we present a contrary example, the two-dimensional (2D) superconductivity in transition-metal carbide can be readily turned into charge density wave (CDW) phases via dilute magnetic doping. Low temperature scanning tunneling microscopy/spectroscopy (STM/STS), transport measurements, and density functional theory (DFT) calculations were employed to investigate Cr-doped superconducting Mo2C crystals in the 2D limit. With ultralow Cr doping (2.7 atom %), the superconductivity of Mo2C is heavily suppressed. Strikingly, an incommensurate density wave (IDW) and a related partially opened gap are observed at a temperature above the superconducting regime. The wave vector of IDW agrees well with the calculated Fermi surface nesting vectors. By further increasing the Cr doping level to 9.4 atom %, a stronger IDW with a smaller periodicity and a larger partial gap appear concurrently. The resistance anomaly implies the onset of the CDW phase. Spatial-resolved and temperature-dependent spectroscopy reveals that such CDW phases exist only in a nonsuperconducting regime and could form long-range orders uniformly. The results provide the understanding for the interplay between charge ordered states and superconductivity in 2D transition-metal carbide.
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Affiliation(s)
- Shaojian Li
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Zongyuan Zhang
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
- Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, P. R. China
| | - Chuan Xu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, P. R. China
| | - Zhen Liu
- Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, P. R. China
| | - Xiaorui Chen
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China
| | - Qi Bian
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Habakubaho Gedeon
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Zhibin Shao
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China
| | - Lijun Liu
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Zhibo Liu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, P. R. China
| | - Ning Kang
- Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, P. R. China
| | - Hui-Ming Cheng
- 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
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen 518055, P. R. 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
| | - Minghu Pan
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China
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24
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Observation of pressure induced charge density wave order and eightfold structure in bulk VSe 2. Sci Rep 2021; 11:18157. [PMID: 34518573 PMCID: PMC8437963 DOI: 10.1038/s41598-021-97630-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 08/19/2021] [Indexed: 11/30/2022] Open
Abstract
Pressure-induced charge density wave (CDW) state can overcome the low-temperature limitation for practical application, thus seeking its traces in experiments is of great importance. Herein, we provide spectroscopic evidence for the emergence of room temperature CDW order in the narrow pressure range of 10–15 GPa in bulk VSe2. Moreover, we discovered an 8-coordination structure of VSe2 with C2/m symmetry in the pressure range of 35–65 GPa by combining the X-ray absorption spectroscopy, X-ray diffraction experiments, and the first-principles calculations. These findings are beneficial for furthering our understanding of the charge modulated structure and its behavior under high pressure.
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25
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Duvjir G, Choi BK, Thi Ly T, Lam NH, Jang K, Dung DD, Chang YJ, Kim J. Multiple charge density wave phases of monolayer VSe 2manifested by graphene substrates. NANOTECHNOLOGY 2021; 32:364002. [PMID: 34062520 DOI: 10.1088/1361-6528/ac06f3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 06/01/2021] [Indexed: 06/12/2023]
Abstract
A combined study of scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES) is conducted to understand the multiple charge density wave (CDW) phases of monolayer (ML) VSe2films manifested by graphene substrates. Submonolayer (∼0.8 ML) VSe2films are prepared on two different substrates of single-layer graphene (SLG) and bi-layer graphene (BLG) on a 6H-SiC(0001). We find that ML VSe2films are less coupled to the SLG substrate compared to that of ML VSe2/BLG. Then, ML VSe2grown on SLG and BLG substrates reveals a very different topography in STM. While ML VSe2/BLG shows one unidirectional modulation of √3 × 2 and √3 × √7 CDW in topography, ML VSe2/SLG presents a clear modulation of 4 × 1 CDW interfering with √3 × 2 and √3 × √7 CDW which has not been previously observed. We explicitly show that the reciprocal vector of 4 × 1 CDW fits perfectly into the long parallel sections of cigar-shaped Fermi surfaces near the M point in ML VSe2, satisfying Fermi surface nesting. Since bulk VSe2is also well-known for the 4 × 4 × 3 CDW formed by Fermi surface nesting, the 4 × 1 CDW in ML VSe2/SLG is attributed to the planar projection of 4 × 4 × 3 CDW in bulk. Our result clarifies the nature of the 4 × 1 CDW in ML VSe2system and is a good example demonstrating the essential role of substrates in two-dimensional transition metal dichalcogenides.
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Affiliation(s)
- Ganbat Duvjir
- Department of Physics, and EHSRC, University of Ulsan, Ulsan 44610, Republic of Korea
| | - Byoung Ki Choi
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - Trinh Thi Ly
- Department of Physics, and EHSRC, University of Ulsan, Ulsan 44610, Republic of Korea
| | - Nguyen Huu Lam
- Department of Physics, and EHSRC, University of Ulsan, Ulsan 44610, Republic of Korea
| | - Kyuha Jang
- Radiation Center for Ultrafast Science, Korea Atomic Energy Research Institute, Daejeon 34057, Republic of Korea
| | - Dang Duc Dung
- Hanoi University of Science and Technology, Hanoi 10000, Vietnam
| | - Young Jun Chang
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
- Department of Smart Cities, University of Seoul, Seoul 02504, Republic of Korea
| | - Jungdae Kim
- Department of Physics, and EHSRC, University of Ulsan, Ulsan 44610, Republic of Korea
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26
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Park TG, Choi BK, Park J, Kim J, Chang YJ, Rotermund F. Interlayer Coupling and Ultrafast Hot Electron Transfer Dynamics in Metallic VSe 2/Graphene van der Waals Heterostructures. ACS NANO 2021; 15:7756-7764. [PMID: 33761743 DOI: 10.1021/acsnano.1c01723] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Atomically thin vanadium diselenide (VSe2) is a two-dimensional transition metal dichalcogenide exhibiting attractive properties due to its metallic 1T phase. With the recent development of methods to manufacture high-quality monolayer VSe2 on van der Waals materials, the outstanding properties of VSe2-based heterostructures have been widely studied for diverse applications. Dimensional reduction and interlayer coupling with a van der Waals substrate lead to its distinguishable characteristics from its bulk counterparts. However, only a few fundamental studies have investigated the interlayer coupling effects and hot electron transfer dynamics in VSe2 heterostructures. In this work, we reveal ultrafast and efficient interlayer hot electron transfer and interlayer coupling effects in VSe2/graphene heterostructures. Femtosecond time-resolved reflectivity measurements showed that hot electrons in VSe2 were transferred to graphene within a 100 fs time scale with high efficiency. Besides, coherent acoustic phonon dynamics indicated interlayer coupling in VSe2/graphene heterostructures and efficient thermal energy transfer to three-dimensional substrates. Our results provide valuable insights into the intriguing properties of metallic transition metal dichalcogenide heterostructures and motivate designing optoelectronic and photonic devices with tailored properties.
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Affiliation(s)
- Tae Gwan Park
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Byoung Ki Choi
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - Junho Park
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Jungdae Kim
- Department of Physics, University of Ulsan, Ulsan 44610, Republic of Korea
| | - Young Jun Chang
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
- Department of Smart Cities, University of Seoul, Seoul 02504, Republic of Korea
| | - Fabian Rotermund
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
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27
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Su J, Liu G, Liu L, Chen J, Hu X, Li Y, Li H, Zhai T. Recent Advances in 2D Group VB Transition Metal Chalcogenides. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2005411. [PMID: 33694286 DOI: 10.1002/smll.202005411] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/25/2020] [Indexed: 06/12/2023]
Abstract
2D materials have received considerable research interest owing to their abundant material systems and remarkable properties. Among them, 2D group VB transition metal chalcogenides (GVTMCs) stand out as emerging 2D metallic materials and significantly broaden the research scope of 2D materials. 2D GVTMCs have great advantages in electrical transport, 2D magnetism, charge density wave, sensing, catalysis, and charge storage, making them attractive in the fields of functional devices and energy chemistry. In this review, the recent progress of 2D GVTMCs is summarized systematically from fundamental properties, growth methodologies to potential applications. The challenges and prospects are also discussed for future research in this field.
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Affiliation(s)
- Jianwei Su
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Guiheng Liu
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Lixin Liu
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Jiazhen Chen
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Xiaozong Hu
- Green Catalysis Center, and College of Chemistry, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Yuan Li
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Huiqiao Li
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Tianyou Zhai
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
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28
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King PDC, Picozzi S, Egdell RG, Panaccione G. Angle, Spin, and Depth Resolved Photoelectron Spectroscopy on Quantum Materials. Chem Rev 2021; 121:2816-2856. [PMID: 33346644 DOI: 10.1021/acs.chemrev.0c00616] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The role of X-ray based electron spectroscopies in determining chemical, electronic, and magnetic properties of solids has been well-known for several decades. A powerful approach is angle-resolved photoelectron spectroscopy, whereby the kinetic energy and angle of photoelectrons emitted from a sample surface are measured. This provides a direct measurement of the electronic band structure of crystalline solids. Moreover, it yields powerful insights into the electronic interactions at play within a material and into the control of spin, charge, and orbital degrees of freedom, central pillars of future solid state science. With strong recent focus on research of lower-dimensional materials and modified electronic behavior at surfaces and interfaces, angle-resolved photoelectron spectroscopy has become a core technique in the study of quantum materials. In this review, we provide an introduction to the technique. Through examples from several topical materials systems, including topological insulators, transition metal dichalcogenides, and transition metal oxides, we highlight the types of information which can be obtained. We show how the combination of angle, spin, time, and depth-resolved experiments are able to reveal "hidden" spectral features, connected to semiconducting, metallic and magnetic properties of solids, as well as underlining the importance of dimensional effects in quantum materials.
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Affiliation(s)
- Phil D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Silvia Picozzi
- Consiglio Nazionale delle Ricerche, CNR-SPIN, Via dei Vestini 31, Chieti 66100, Italy
| | - Russell G Egdell
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Giancarlo Panaccione
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
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29
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Biswas D, Jones AJH, Majchrzak P, Choi BK, Lee TH, Volckaert K, Feng J, Marković I, Andreatta F, Kang CJ, Kim HJ, Lee IH, Jozwiak C, Rotenberg E, Bostwick A, Sanders CE, Zhang Y, Karras G, Chapman RT, Wyatt AS, Springate E, Miwa JA, Hofmann P, King PDC, Chang YJ, Lanatà N, Ulstrup S. Ultrafast Triggering of Insulator-Metal Transition in Two-Dimensional VSe 2. NANO LETTERS 2021; 21:1968-1975. [PMID: 33600187 DOI: 10.1021/acs.nanolett.0c04409] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The transition-metal dichalcogenide VSe2 exhibits an increased charge density wave transition temperature and an emerging insulating phase when thinned to a single layer. Here, we investigate the interplay of electronic and lattice degrees of freedom that underpin these phases in single-layer VSe2 using ultrafast pump-probe photoemission spectroscopy. In the insulating state, we observe a light-induced closure of the energy gap, which we disentangle from the ensuing hot carrier dynamics by fitting a model spectral function to the time-dependent photoemission intensity. This procedure leads to an estimated time scale of 480 fs for the closure of the gap, which suggests that the phase transition in single-layer VSe2 is driven by electron-lattice interactions rather than by Mott-like electronic effects. The ultrafast optical switching of these interactions in SL VSe2 demonstrates the potential for controlling phase transitions in 2D materials with light.
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Affiliation(s)
- Deepnarayan Biswas
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Alfred J H Jones
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Paulina Majchrzak
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Byoung Ki Choi
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - Tsung-Han Lee
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08856, United States
| | - Klara Volckaert
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Jiagui Feng
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, U.K
- Suzhou Institute of Nano-Tech. and Nanobionics (SINANO), CAS, 398 Ruoshui Road, SEID, SIP, Suzhou 215123, China
| | - Igor Marković
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, U.K
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Federico Andreatta
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Chang-Jong Kang
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08856, United States
| | - Hyuk Jin Kim
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - In Hak Lee
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - Chris Jozwiak
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Eli Rotenberg
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Aaron Bostwick
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Charlotte E Sanders
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Yu Zhang
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Gabriel Karras
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Richard T Chapman
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Adam S Wyatt
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Emma Springate
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Jill A Miwa
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Philip Hofmann
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Phil D C King
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, U.K
| | - Young Jun Chang
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
- Department of Smart Cities, University of Seoul, Seoul, 02504, Republic of Korea
| | - Nicola Lanatà
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
- Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, 10691 Stockholm, Sweden
| | - Søren Ulstrup
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
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30
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Lin MK, He T, Hlevyack JA, Chen P, Mo SK, Chou MY, Chiang TC. Coherent Electronic Band Structure of TiTe 2/TiSe 2 Moiré Bilayer. ACS NANO 2021; 15:3359-3364. [PMID: 33570920 DOI: 10.1021/acsnano.0c10352] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A van der Waals bonded moiré bilayer formed by sequential growth of TiSe2 and TiTe2 monolayers exhibits emergent electronic structure as evidenced by angle-resolved photoemission band mapping. The two monolayers adopt the same lattice orientation but incommensurate lattice constants. Despite the lack of translational symmetry, sharp dispersive bands are observed. The dispersion relations appear distinct from those for the component monolayers alone. Theoretical calculations illustrate the formation of composite bands by coherent electronic coupling despite the weak interlayer bonding, which leads to band renormalization and energy shifts.
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Affiliation(s)
- Meng-Kai Lin
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Tao He
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Joseph A Hlevyack
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Peng Chen
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, and Shanghai Center for Complex Physics, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Mei-Yin Chou
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - T-C Chiang
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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31
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van der Waals driven anharmonic melting of the 3D charge density wave in VSe 2. Nat Commun 2021; 12:598. [PMID: 33500397 PMCID: PMC7838422 DOI: 10.1038/s41467-020-20829-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 12/22/2020] [Indexed: 11/24/2022] Open
Abstract
Understanding of charge-density wave (CDW) phases is a main challenge in condensed matter due to their presence in high-Tc superconductors or transition metal dichalcogenides (TMDs). Among TMDs, the origin of the CDW in VSe2 remains highly debated. Here, by means of inelastic x-ray scattering and first-principles calculations, we show that the CDW transition is driven by the collapse at 110 K of an acoustic mode at qCDW = (2.25 0 0.7) r.l.u. The softening starts below 225 K and expands over a wide region of the Brillouin zone, identifying the electron-phonon interaction as the driving force of the CDW. This is supported by our calculations that determine a large momentum-dependence of the electron-phonon matrix-elements that peak at the CDW wave vector. Our first-principles anharmonic calculations reproduce the temperature dependence of the soft mode and the TCDW onset only when considering the out-of-plane van der Waals interactions, which reveal crucial for the melting of the CDW phase. The nature of the charge density wave transition in VSe2 is still debated. Here, the authors demonstrate that the transition is mainly driven by electron-phonon interactions, despite the presence of the Fermi-surface nesting, and that Wan-der-Waals forces are responsible for melting of the charge density wave order.
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32
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Lin MK, Hlevyack JA, Chen P, Liu RY, Mo SK, Chiang TC. Charge Instability in Single-Layer TiTe_{2} Mediated by van der Waals Bonding to Substrates. PHYSICAL REVIEW LETTERS 2020; 125:176405. [PMID: 33156647 DOI: 10.1103/physrevlett.125.176405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 09/10/2020] [Indexed: 06/11/2023]
Abstract
Single layers of transition metal dichalcogenides are of interest for emergent properties; an often-neglected issue is substrate effects. Our experiments show that the charge density wave in a single-layer TiTe_{2} grown on PtTe_{2} films is strongly suppressed by increasing the PtTe_{2} substrate thickness. Given that the interfacial bonding remains of the weak incommensurate van der Waals type, the observed changes are correlated with a thickness-dependent metallicity transformation in the PtTe_{2} substrate. The results illustrate the crucial role of the substrate in single-layer physics.
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Affiliation(s)
- Meng-Kai Lin
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Joseph A Hlevyack
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Peng Chen
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science and Shanghai Center for Complex Physics, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ro-Ya Liu
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Institute of Physics, Academia Sinica, Taipei 10617, Taiwan
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - T-C Chiang
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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33
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Boukhvalov DW, Politano A. Unveiling the origin of room-temperature ferromagnetism in monolayer VSe 2: the role of extrinsic effects. NANOSCALE 2020; 12:20875-20882. [PMID: 33047776 DOI: 10.1039/d0nr04663a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Room-temperature ferromagnetism in monolayer vanadium diselenide (VSe2) on graphite is the object of a controversial debate. Herein, we unveil the contribution from extrinsic factors to the magnetic properties of monolayer VSe2 by means of density functional theory. Specifically, we demonstrate that either intrinsic defects or the adsorption of molecules enhances ferromagnetic interactions. The expansion of the VSe2 lattice increases the magnetic moment on vanadium ions, whereas both compression and out-of-plane distortion withdraw magnetic moments. The exchange interactions between vanadium ions and magnetic defects (vacancies and impurities) in the surface and subsurface layers of the substrate are able to turn the unstable two-dimensional (2D) ferromagnetism into stable three-dimensional (3D) ferromagnetism. Definitely, the combination of effects related to chemisorption, substrate-induced distortion and magnetic defects of the substrate could enhance or suppress ferromagnetism in monolayer VSe2.
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Affiliation(s)
- Danil W Boukhvalov
- College of Science, Institute of Materials Physics and Chemistry, Nanjing Forestry University, Nanjing 210037, P. R. China. and Institute of Physics and Technology, Ural Federal University, Mira Street 19, 620002 Yekaterinburg, Russia
| | - Antonio Politano
- Department of Physical and Chemical Sciences, University of L'Aquila, via Vetoio, 67100 L'Aquila, AQ, Italy and CNR-IMM Istituto per la Microelettronica e Microsistemi, VIII strada 5, I-95121 Catania, Italy
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Lasek K, Coelho PM, Zberecki K, Xin Y, Kolekar SK, Li J, Batzill M. Molecular Beam Epitaxy of Transition Metal (Ti-, V-, and Cr-) Tellurides: From Monolayer Ditellurides to Multilayer Self-Intercalation Compounds. ACS NANO 2020; 14:8473-8484. [PMID: 32584543 DOI: 10.1021/acsnano.0c02712] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Material growth by van der Waals epitaxy has the potential to isolate monolayer (ML) materials and synthesize ultrathin films not easily prepared by exfoliation or other growth methods. Here, the synthesis of the early transition metal (Ti, V, and Cr) tellurides by molecular beam epitaxy (MBE) in the mono- to few-layer regime is investigated. The layered ditellurides of these materials are known for their intriguing quantum- and layer dependent- properties. Here we show by a combination of in situ sample characterization and comparison with computational predictions that ML ditellurides with octahedral 1T structure are readily grown, but for multilayers, the transition metal dichalcogenide (TMDC) formation competes with self-intercalated compounds. CrTe2, a TMDC that is known to be metastable in bulk and easily decomposes into intercalation compounds, has been synthesized successfully in the ML regime at low growth temperatures. At elevated growth temperatures or for multilayers, only the intercalation compound, equivalent to a bulk Cr3Te4, could be obtained. ML VTe2 is more stable and can be synthesized at higher growth temperatures in the ML regime, but multilayers also convert to a bulk-equivalent V3Te4 compound. TiTe2 is the most stable of the TMDCs studied; nevertheless, a detailed analysis of multilayers also indicates the presence of intercalated metals. Computation suggests that the intercalation-induced distortion of the TMDC-layers is much reduced in Ti-telluride compared to V-, and Cr-telluride. This makes the identification of intercalated materials by scanning tunneling microscopy more challenging for Ti-telluride. The identification of self-intercalation compounds in MBE grown multilayer chalcogenides may explain observed lattice distortions in previously reported MBE grown early transition metal chalcogenides. On the other hand, these intercalation compounds in their ultrathin limit can be considered van der Waals materials in their own right. This class of materials is only accessible by direct growth methods but may be used as "building blocks" in MBE-grown van der Waals heterostructures. Controlling their growth is an important step for understanding and studying the properties of these materials.
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Affiliation(s)
- Kinga Lasek
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Paula Mariel Coelho
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Krzysztof Zberecki
- Faculty of Physics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw, Poland
| | - Yan Xin
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Sadhu K Kolekar
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Jingfeng Li
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Matthias Batzill
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
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Xue Y, Zhang Y, Wang H, Lin S, Li Y, Dai JY, Lau SP. Thickness-dependent magnetotransport properties in 1T VSe 2 single crystals prepared by chemical vapor deposition. NANOTECHNOLOGY 2020; 31:145712. [PMID: 31860893 DOI: 10.1088/1361-6528/ab6478] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Two-dimensional (2D) metallic transition metal dichalcogenides (TMDs) exhibit fascinating quantum effects, such as charge-density-wave (CDW) and weak antilocalization (WAL) effect. Herein, low temperature synthesis of 1T phase VSe2 single crystals with thickness ranging from 3 to 41 nm by chemical vapor deposition (CVD) is reported. The VSe2 shows a decreasing phase transition temperature of the CDW when the thickness is decreased. Moreover, low-temperature magnetotransport measurements demonstrate a linear positive and non-saturating magnetoresistance (MR) of 35% from a 35 nm thick VSe2 at 15 T and 2 K due to CDW induce mobility fluctuations. Surprisingly, Kohler's rule analysis of the MR reveals the non-applicability of Kohler's rule for temperature above 50 K indicating that the MR behavior cannot be described in terms of semiclassical transport on a single Fermi surface with a single scattering time. Furthermore, WAL effect is observed in the 4.2 nm thick VSe2 at low magnetic fields at 2 K, revealing the contribution of the quantum interference effect at the 2D limit. The phase coherence length [Formula: see text] and spin-orbit scattering length [Formula: see text] were determined to be 73 nm and 18 nm at 2 K, respectively. Our work opens new avenues to study the fundamental quantum phenomena in CVD-deposited TMDs.
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Affiliation(s)
- Yunzhou Xue
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, People's Republic of China
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36
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Lin MK, Villaos RAB, Hlevyack JA, Chen P, Liu RY, Hsu CH, Avila J, Mo SK, Chuang FC, Chiang TC. Dimensionality-Mediated Semimetal-Semiconductor Transition in Ultrathin PtTe_{2} Films. PHYSICAL REVIEW LETTERS 2020; 124:036402. [PMID: 32031832 DOI: 10.1103/physrevlett.124.036402] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Indexed: 06/10/2023]
Abstract
Platinum ditelluride (PtTe_{2}), a type-II Dirac semimetal, remains semimetallic in ultrathin films down to just two triatomic layers (TLs) with a negative gap of -0.36 eV. Further reduction of the film thickness to a single TL induces a Lifshitz electronic transition to a semiconductor with a large positive gap of +0.79 eV. This transition is evidenced by experimental band structure mapping of films prepared by layer-resolved molecular beam epitaxy, and by comparing the data to first-principles calculations using a hybrid functional. The results demonstrate a novel electronic transition at the two-dimensional limit through film thickness control.
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Affiliation(s)
- Meng-Kai Lin
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | | | - Joseph A Hlevyack
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Peng Chen
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Shanghai Center for Complex Physics, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ro-Ya Liu
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Institute of Physics, Academia Sinica, Taipei 10617, Taiwan
| | - Chia-Hsiu Hsu
- Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - José Avila
- Synchrotron SOLEIL and Universite Paris-Saclay, L'Orme des Merisiers, BP48, 91190 Saint-Aubin, France
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Feng-Chuan Chuang
- Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - T-C Chiang
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Sereika R, Park C, Kenney-Benson C, Bandaru S, English NJ, Yin Q, Lei H, Chen N, Sun CJ, Heald SM, Ren J, Chang J, Ding Y, Mao HK. Novel Superstructure-Phase Two-Dimensional Material 1 T-VSe 2 at High Pressure. J Phys Chem Lett 2020; 11:380-386. [PMID: 31821003 DOI: 10.1021/acs.jpclett.9b03247] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A superstructure can elicit versatile new properties in materials by breaking their original geometrical symmetries. It is an important topic in the layered graphene-like two-dimensional transition metal dichalcogenides, but its origin remains unclear. Using diamond-anvil cell techniques, synchrotron X-ray diffraction, X-ray absorption, and first-principles calculations, we show that the evolution from weak van der Waals bonding to Heisenberg covalent bonding between layers induces an isostructural transition in quasi-two-dimensional 1T-type VSe2 at high pressure. Furthermore, our results show that high pressure induces a novel superstructure at 15.5 GPa rather than suppresses it as it would normally, which is unexpected. It is driven by Fermi-surface nesting, enhanced by pressure-induced distortion. The results suggest that the superstructure not only appears in the two-dimensional structure but also can emerge in the pressure-tuned three-dimensional structure with new symmetry and develop superconductivity.
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Affiliation(s)
- Raimundas Sereika
- Center for High Pressure Science and Technology Advanced Research , Beijing 100094 , China
- Vytautas Magnus University , K. Donelaičio Street 58 , Kaunas 44248 , Lithuania
| | - Changyong Park
- High Pressure Collaborative Access Team, X-ray Science Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Curtis Kenney-Benson
- High Pressure Collaborative Access Team, X-ray Science Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Sateesh Bandaru
- School of Chemical and Bioprocess Engineering , University College Dublin , Belfield, Dublin 4 , Ireland
- College of Materials and Environmental Engineering, Institute for Advanced Magnetic Materials , Hangzhou Dianzi University , Hangzhou 310018 , China
| | - Niall J English
- School of Chemical and Bioprocess Engineering , University College Dublin , Belfield, Dublin 4 , Ireland
| | - Qiangwei Yin
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices , Renmin University of China , Beijing 100872 , China
| | - Hechang Lei
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices , Renmin University of China , Beijing 100872 , China
| | - Ning Chen
- Canadian Light Source , 44 Innovation Boulevard , Saskatoon , SK S7N 2V3 , Canada
| | - Cheng-Jun Sun
- X-ray Science Division , Advanced Photon Source, Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Steve M Heald
- X-ray Science Division , Advanced Photon Source, Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Jichang Ren
- Nano and Heterogeneous Materials Center, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , People's Republic of China
| | - Jun Chang
- College of Physics and Information Technology , Shaanxi Normal University , Xi'an 710119 , P. R. China
| | - Yang Ding
- Center for High Pressure Science and Technology Advanced Research , Beijing 100094 , China
| | - Ho-Kwang Mao
- Center for High Pressure Science and Technology Advanced Research , Beijing 100094 , China
- Geophysical Laboratory , Carnegie Institution of Washington , Washington, D.C. 20015 , United States
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Nakano M, Wang Y, Yoshida S, Matsuoka H, Majima Y, Ikeda K, Hirata Y, Takeda Y, Wadati H, Kohama Y, Ohigashi Y, Sakano M, Ishizaka K, Iwasa Y. Intrinsic 2D Ferromagnetism in V 5Se 8 Epitaxial Thin Films. NANO LETTERS 2019; 19:8806-8810. [PMID: 31714089 DOI: 10.1021/acs.nanolett.9b03614] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The discoveries of intrinsic ferromagnetism in atomically thin van der Waals crystals have opened a new research field enabling fundamental studies on magnetism at two-dimensional (2D) limit as well as development of magnetic van der Waals heterostructures. Currently, a variety of 2D ferromagnetism has been explored mainly by mechanically exfoliating "originally ferromagnetic (FM)" van der Waals crystals, while a bottom-up approach by thin-film growth technique has demonstrated emergent 2D ferromagnetism in a variety of "originally non-FM" van der Waals materials. Here we demonstrate that V5Se8 epitaxial thin films grown by molecular-beam epitaxy exhibit emergent 2D ferromagnetism with intrinsic spin polarization of the V 3d electrons despite that the bulk counterpart is "originally antiferromagnetic". Moreover, thickness-dependence measurements reveal that this newly developed 2D ferromagnet could be classified as an itinerant 2D Heisenberg ferromagnet with weak magnetic anisotropy, broadening a lineup of 2D magnets to those potentially beneficial for future spintronics applications.
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Affiliation(s)
- Masaki Nakano
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
- RIKEN Center for Emergent Matter Science , Wako 351-0198 , Japan
| | - Yue Wang
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Satoshi Yoshida
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Hideki Matsuoka
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Yuki Majima
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Keisuke Ikeda
- Department of Physics , the University of Tokyo , Tokyo 113-0033 , Japan
| | - Yasuyuki Hirata
- Department of Physics , the University of Tokyo , Tokyo 113-0033 , Japan
- The Institute for Solid State Physics , the University of Tokyo , Kashiwa 227-8581 , Japan
| | - Yukiharu Takeda
- Materials Sciences Research Center , Japan Atomic Energy Agency , Koto City 679-5148 , Hyogo , Japan
| | - Hiroki Wadati
- Department of Physics , the University of Tokyo , Tokyo 113-0033 , Japan
- The Institute for Solid State Physics , the University of Tokyo , Kashiwa 227-8581 , Japan
| | - Yoshimitsu Kohama
- The Institute for Solid State Physics , the University of Tokyo , Kashiwa 227-8581 , Japan
| | - Yuta Ohigashi
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Masato Sakano
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Kyoko Ishizaka
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
- RIKEN Center for Emergent Matter Science , Wako 351-0198 , Japan
| | - Yoshihiro Iwasa
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
- RIKEN Center for Emergent Matter Science , Wako 351-0198 , Japan
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Duvjir G, Choi BK, Ly TT, Lam NH, Chun SH, Jang K, Soon A, Chang YJ, Kim J. Novel polymorphic phase of two-dimensional VSe 2: the 1T' structure and its lattice dynamics. NANOSCALE 2019; 11:20096-20101. [PMID: 31612892 DOI: 10.1039/c9nr06076f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Polymorphisms allowing multiple structural phases are among the most fascinating properties of transition metal dichalcogenides (TMDs). Herein, the polymorphic 1T' phase and its lattice dynamics for bilayer VSe2 grown on epitaxial bilayer graphene are investigated via low temperature scanning tunneling microscopy (STM). The 1T' structure, mostly observed in group-6 TMDs, is unexpected in VSe2, which is a group-5 TMD. Emergence of the 1T' structure in bilayer VSe2 suggests the important roles of interface and layer configurations, providing new possibilities regarding the polymorphism of TMDs. Detailed topographical analysis elucidates the microscopic nature of the 1T' structure, confirming that Se-like and V-like surfaces can be resolved depending on the polarity of the sample bias. In addition, bilayer VSe2 can transit from a static state of the 1T' phase to a dynamic state consisting of lattice vibrations, triggered by tunneling current from the STM tip. Topography also shows hysteretic behavior during the static-dynamic transition, which is attributed to latent energy existing between the two states. The observed lattice dynamics involve vibrational motion of the Se atoms and the middle V atoms. Our observations will provide important information to establish in-depth understanding of the microscopic nature of 1T' structures and the polymorphism of two-dimensional TMDs.
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Affiliation(s)
- Ganbat Duvjir
- Department of Physics, BRL, and EHSRC, University of Ulsan, Ulsan 44610, Republic of Korea.
| | - Byoung Ki Choi
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea.
| | - Trinh Thi Ly
- Department of Physics, BRL, and EHSRC, University of Ulsan, Ulsan 44610, Republic of Korea.
| | - Nguyen Huu Lam
- Department of Physics, BRL, and EHSRC, University of Ulsan, Ulsan 44610, Republic of Korea.
| | - Seung-Hyun Chun
- Department of Physics, Sejong University, Seoul 05006, Korea
| | - Kyuha Jang
- Radiation Center for Ultrafast Science, Korea Atomic Energy Research Institute, Daejeon 34057, Korea
| | - Aloysius Soon
- Department of Materials Science and Engineering and Center for Artificial Synesthesia Materials Discovery, Yonsei University, Seoul 03722, Korea
| | - Young Jun Chang
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea.
| | - Jungdae Kim
- Department of Physics, BRL, and EHSRC, University of Ulsan, Ulsan 44610, Republic of Korea.
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Coelho PM, Lasek K, Nguyen Cong K, Li J, Niu W, Liu W, Oleynik II, Batzill M. Monolayer Modification of VTe 2 and Its Charge Density Wave. J Phys Chem Lett 2019; 10:4987-4993. [PMID: 31411022 DOI: 10.1021/acs.jpclett.9b01949] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Interlayer interactions in layered transition metal dichalcogenides are known to be important for describing their electronic properties. Here, we demonstrate that the absence of interlayer coupling in monolayer VTe2 also causes their structural modification from a distorted 1T' structure in bulk and multilayer samples to a hexagonal 1T structure in the monolayer. X-ray photoemission spectroscopy indicates that this structural transition is associated with electron transfer from the vanadium d bands to the tellurium atoms for the monolayer. This charge transfer may reduce the in-plane d orbital hybridization and thus favor the undistorted 1T structure. Phonon-dispersion calculations show that, in contrast to the 1T' structure, the 1T structure exhibits imaginary phonon modes that lead to a charge density wave (CDW) instability, which is also observed by low-temperature scanning tunneling microscopy as a 4 × 4 periodic lattice distortion. Thus, this work demonstrates a novel CDW material, whose properties are tuned by interlayer interactions.
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Affiliation(s)
- Paula Mariel Coelho
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Kinga Lasek
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Kien Nguyen Cong
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Jingfeng Li
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Wei Niu
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, U.K
- New Energy Technology Engineering Laboratory of Jiangsu Provence and School of Science, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Wenqing Liu
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, U.K
| | - Ivan I Oleynik
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Matthias Batzill
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
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Zhang W, Zhang L, Wong PKJ, Yuan J, Vinai G, Torelli P, van der Laan G, Feng YP, Wee ATS. Magnetic Transition in Monolayer VSe 2 via Interface Hybridization. ACS NANO 2019; 13:8997-9004. [PMID: 31306576 DOI: 10.1021/acsnano.9b02996] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Magnetism in monolayer (ML) VSe2 has attracted broad interest in spintronics, while existing reports have not reached consensus. Using element-specific X-ray magnetic circular dichroism, a magnetic transition in ML VSe2 has been demonstrated at the contamination-free interface between Co and VSe2. Through interfacial hybridization with a Co atomic overlayer, a magnetic moment of about 0.4 μB per V atom in ML VSe2 is revealed, approaching values predicted by previous theoretical calculations. Promotion of the ferromagnetism in ML VSe2 is accompanied by its antiferromagnetic coupling to Co and a reduction in the spin moment of Co. In comparison to the absence of this interface-induced ferromagnetism at the Fe/ML MoSe2 interface, these findings at the Co/ML VSe2 interface provide clear proof that the ML VSe2, initially with magnetic disorder, is on the verge of magnetic transition.
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Affiliation(s)
- Wen Zhang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
| | - Lei Zhang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
| | - Ping Kwan Johnny Wong
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546
| | - Jiaren Yuan
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
| | - Giovanni Vinai
- Laboratorio TASC , IOM-CNR , S.S. 14 km 163.5, Basovizza , 34149 Trieste , Italy
| | - Piero Torelli
- Laboratorio TASC , IOM-CNR , S.S. 14 km 163.5, Basovizza , 34149 Trieste , Italy
| | - Gerrit van der Laan
- Magnetic Spectroscopy Group , Diamond Light Source , Didcot OX11 0DE , United Kingdom
| | - Yuan Ping Feng
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
| | - Andrew T S Wee
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
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Shao Z, Fu ZG, Li S, Cao Y, Bian Q, Sun H, Zhang Z, Gedeon H, Zhang X, Liu L, Cheng Z, Zheng F, Zhang P, Pan M. Strongly Compressed Few-Layered SnSe 2 Films Grown on a SrTiO 3 Substrate: The Coexistence of Charge Ordering and Enhanced Interfacial Superconductivity. NANO LETTERS 2019; 19:5304-5312. [PMID: 31287705 DOI: 10.1021/acs.nanolett.9b01766] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
High pressure has been demonstrated to be a powerful approach of producing novel condensed-matter states, particularly in tuning the superconducting transition temperature (Tc) of the superconductivity in a clean fashion without involving the complexity of chemical doping. However, the challenge of high-pressure experiment hinders further in-depth research for underlying mechanisms. Here, we have successfully synthesized continuous layer-controllable SnSe2 films on SrTiO3 substrate using molecular beam epitaxy. By means of scanning tunneling microscopy/spectroscopy (STM/S) and Raman spectroscopy, we found that the strong compressive strain is intrinsically built in few-layers films, with a largest equivalent pressure up to 23 GPa in the monolayer. Upon this, unusual 2 × 2 charge ordering is induced at the occupied states in the monolayer, accompanied by prominent decrease in the density of states (DOS) near the Fermi energy (EF), resembling the gap states of CDW reported in transition metal dichalcogenide (TMD) materials. Subsequently, the coexistence of charge ordering and the interfacial superconductivity is observed in bilayer films as a result of releasing the compressive strain. In conjunction with spatially resolved spectroscopic study and first-principles calculation, we find that the enhanced interfacial superconductivity with an estimated Tc of 8.3 K is observed only in the 1 × 1 region. Such superconductivity can be ascribed to a combined effect of interfacial charge transfer and compressive strain, which leads to a considerable downshift of the conduction band minimum and an increase in the DOS at EF. Our results provide an attractive platform for further in-depth investigation of compression-induced charge ordering (monolayer) and the interplay between charge ordering and superconductivity (bilayer). Meanwhile, it has opened up a pathway to prepare strongly compressed two-dimensional materials by growing onto a SrTiO3 substrate, which is promising to induce superconductivity with a higher Tc.
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Affiliation(s)
- Zhibin Shao
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Zhen-Guo Fu
- Institute of Applied Physics and Computational Mathematics , Beijing 100088 , China
| | - Shaojian Li
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Yan Cao
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Qi Bian
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Haigen Sun
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Zongyuan Zhang
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Habakubaho Gedeon
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Xin Zhang
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Lijun Liu
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Zhengwang Cheng
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Fawei Zheng
- Institute of Applied Physics and Computational Mathematics , Beijing 100088 , China
| | - Ping Zhang
- Institute of Applied Physics and Computational Mathematics , Beijing 100088 , China
| | - Minghu Pan
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
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Liu H, Bao L, Zhou Z, Che B, Zhang R, Bian C, Ma R, Wu L, Yang H, Li J, Gu C, Shen CM, Du S, Gao HJ. Quasi-2D Transport and Weak Antilocalization Effect in Few-layered VSe 2. NANO LETTERS 2019; 19:4551-4559. [PMID: 31241975 DOI: 10.1021/acs.nanolett.9b01412] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
With strong spin-orbit coupling (SOC), ultrathin two-dimensional (2D) transitional metal chalcogenides (TMDs) are predicted to exhibit weak antilocalization (WAL) effect at low temperatures. The observation of WAL effect in VSe2 is challenging due to the relative weak SOC and three-dimensional (3D) transport nature in thick VSe2. Here, we report on the observation of quasi-2D transport and WAL effect in sublimed-salt-assisted low-temperature chemical vapor deposition (CVD) grown few-layered high-quality VSe2 nanosheets. The WAL magnitudes in magnetoconductance can be perfectly fitted by the 2D Hikami-Larkin-Nagaoka (HLN) equation in the presence of strong SOC, by which the spin-orbit scattering length lSO and phase coherence length lϕ have been extracted. The phase coherence length lϕ shows a power law dependence with temperature, lϕ∼ T-1/2, revealing an electron-electron interaction-dominated dephasing mechanism. Such sublimed-salt-assisted growth of high-quality few-layered VSe2 and the observation of WAL pave the way for future spintronic and valleytronic applications.
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Affiliation(s)
- Hongtao Liu
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
| | - Lihong Bao
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , P. R. China
| | - Zhang Zhou
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
| | - Bingyu Che
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
| | - Ruizi Zhang
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
| | - Ce Bian
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
| | - Ruisong Ma
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
| | - Liangmei Wu
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
| | - Haifang Yang
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
| | - Junjie Li
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
| | - Changzhi Gu
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
| | - Cheng-Min Shen
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , P. R. China
| | - Shixuan Du
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , P. R. China
| | - Hong-Jun Gao
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing , 100190 , P. R. China
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Wong PKJ, Zhang W, Bussolotti F, Yin X, Herng TS, Zhang L, Huang YL, Vinai G, Krishnamurthi S, Bukhvalov DW, Zheng YJ, Chua R, N'Diaye AT, Morton SA, Yang CY, Ou Yang KH, Torelli P, Chen W, Goh KEJ, Ding J, Lin MT, Brocks G, de Jong MP, Castro Neto AH, Wee ATS. Evidence of Spin Frustration in a Vanadium Diselenide Monolayer Magnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1901185. [PMID: 30997712 DOI: 10.1002/adma.201901185] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 03/30/2019] [Indexed: 06/09/2023]
Abstract
Monolayer VSe2 , featuring both charge density wave and magnetism phenomena, represents a unique van der Waals magnet in the family of metallic 2D transition-metal dichalcogenides (2D-TMDs). Herein, by means of in situ microscopy and spectroscopic techniques, including scanning tunneling microscopy/spectroscopy, synchrotron X-ray and angle-resolved photoemission, and X-ray absorption, direct spectroscopic signatures are established, that identify the metallic 1T-phase and vanadium 3d1 electronic configuration in monolayer VSe2 grown on graphite by molecular-beam epitaxy. Element-specific X-ray magnetic circular dichroism, complemented with magnetic susceptibility measurements, further reveals monolayer VSe2 as a frustrated magnet, with its spins exhibiting subtle correlations, albeit in the absence of a long-range magnetic order down to 2 K and up to a 7 T magnetic field. This observation is attributed to the relative stability of the ferromagnetic and antiferromagnetic ground states, arising from its atomic-scale structural features, such as rotational disorders and edges. The results of this study extend the current understanding of metallic 2D-TMDs in the search for exotic low-dimensional quantum phenomena, and stimulate further theoretical and experimental studies on van der Waals monolayer magnets.
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Affiliation(s)
- Ping Kwan Johnny Wong
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Wen Zhang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Fabio Bussolotti
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*Star), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore
| | - Xinmao Yin
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Tun Seng Herng
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Lei Zhang
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Yu Li Huang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Giovanni Vinai
- Instituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S. Km 163.5, Trieste, I-34149, Italy
| | - Sridevi Krishnamurthi
- Computational Materials Science, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands
| | - Danil W Bukhvalov
- College of Science, Institute of Materials Physics and Chemistry, Nanjing Forestry University, Nanjing, 210037, P. R. China
- Institute of Physics and Technology, Ural Federal University, Mira Street 19, 620002, Yekaterinburg, Russia
| | - Yu Jie Zheng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Rebekah Chua
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Alpha T N'Diaye
- Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Simon A Morton
- Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Chao-Yao Yang
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Kui-Hon Ou Yang
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Piero Torelli
- Instituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S. Km 163.5, Trieste, I-34149, Italy
| | - Wei Chen
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Department of Chemistry, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Kuan Eng Johnson Goh
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*Star), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore
| | - Jun Ding
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Minn-Tsong Lin
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Geert Brocks
- Computational Materials Science, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands
| | - Michel P de Jong
- NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands
| | - Antonio H Castro Neto
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Andrew Thye Shen Wee
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
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45
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Pushkarev GV, Mazurenko VG, Mazurenko VV, Boukhvalov DW. Structural phase transitions in VSe2: energetics, electronic structure and magnetism. Phys Chem Chem Phys 2019; 21:22647-22653. [DOI: 10.1039/c9cp03726h] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
First principles calculations of the magnetic and electronic properties of VSe2 describing the transition between two structural phases (H,T) were performed.
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Affiliation(s)
| | | | | | - Danil W. Boukhvalov
- College of Science
- Institute of Materials Physics and Chemistry
- Nanjing Forestry University
- Nanjing 210037
- P. R. China
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