1
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Wang X, Wang D, Zou Y, Wang T, Li Y, Niu X, Song G, Wang B, Liu Y. Quantum States Induced by Strong Interface Coupling in a 2D VSe 2/Bi 2Se 3 Heterostructure. ACS NANO 2024. [PMID: 39185922 DOI: 10.1021/acsnano.4c03139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
We have successfully fabricated single-layer (SL) 1T-VSe2/Bi2Se3 heterostructures using molecular beam epitaxy (MBE), which exhibits uniform moiré patterns on the heterostructure surface. Scanning tunneling microscopy/spectroscopy (STM/STS) reveals a notable quantum state near the Fermi energy, robust across the entire moiré lattice. This quantum state peak shifts slightly across different domain ranges, suggesting an elastic strain dependence in SL VSe2, confirmed by geometric phase analysis (GPA) simulations. Density functional theory (DFT) calculations indicate that the enhanced quantum state results from charge redistribution between the substrate and the epifilm with the orbitals of Se atoms in the deformed VSe2 playing a dominant role.
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Affiliation(s)
- Xin Wang
- College of Chemistry, Beijing Normal University, Beijing 100875, PR China
| | - Donghui Wang
- College of Chemistry, Beijing Normal University, Beijing 100875, PR China
| | - Yuxiao Zou
- Kunming Institute of Physics, Kunming 650223, PR China
| | - Tao Wang
- State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, PR China
| | - Yunliang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, PR China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Xiaobin Niu
- School of materials and Energy, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, PR China
| | - Guofeng Song
- Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, PR China
- College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Bin Wang
- State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, PR China
| | - Ying Liu
- College of Chemistry, Beijing Normal University, Beijing 100875, PR China
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2
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Ozguven Y, Guler HE, Billur AA, Mogulkoc A, Modarresi M. Robust ferromagnetism in two-dimensional GeC/CrN heterobilayers. Phys Chem Chem Phys 2023; 25:22370-22379. [PMID: 37580987 DOI: 10.1039/d3cp01731a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
We have investigated the electronic and finite temperature magnetic properties of germanium carbide (GeC) and ferromagnetic chromium nitride (CrN) heterobilayers by using first-principles calculations based on density functional theory with Hubbard U correction and an effective anisotropic Heisenberg spin model. The dynamical stability of different stacking formations of heterobilayers is ensured by considering the phonon spectra. All the stacking patterns show half-metallicity with an out-of-plane easy-axis ferromagnetic ground state. We find a high Curie temperature for GeC/CrN heterobilayers within the random phase approximation (RPA). In addition to the symmetric stackings, i.e., AA and AB, the electronic properties of non-symmetric stackings at three different twist angles are also analyzed. The electronic structure analysis of twisted structures demonstrates that the half-metallicity of the GeC/CrN heterobilayer is stack independent. Furthermore, we have investigated the electronic properties, magnetic anisotropy energy, Curie temperature, and spin wave spectrum in the presence of biaxial strain. It is shown that the compressive strain dramatically reduces the magnetic anisotropy energy of the GeC/CrN heterobilayer and Curie temperature, but the Curie temperature still remains well above room temperature for all strain values. The increasing values of tensile strain reduce the magnetic exchange while it increases the magnetic anisotropy energy of the heterobilayer system which enhances the Curie temperature of the structures. The monolayer CrN on the GeC with a wide band gap and commensurate lattice together with a high Tc value can be a feasible candidate for future spintronic applications.
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Affiliation(s)
- Y Ozguven
- Department of Metallurgical and Materials Engineering, Sivas Cumhuriyet University, 58140, Sivas, Turkey
| | - H E Guler
- Department of Physics, Faculty of Sciences, Ankara University, 06100 Tandogan, Ankara, Turkey.
| | - A A Billur
- Department of Physics, Sivas Cumhuriyet University, 58140 Sivas, Turkey
| | - A Mogulkoc
- Department of Physics, Faculty of Sciences, Ankara University, 06100 Tandogan, Ankara, Turkey.
| | - M Modarresi
- Department of Physics, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
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3
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Yang F, Hu P, Yang FF, Chen B, Yin F, Sun R, Hao K, Zhu F, Wang K, Yin Z. Emerging Enhancement and Regulation Strategies for Ferromagnetic 2D Transition Metal Dichalcogenides. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023:e2300952. [PMID: 37178366 PMCID: PMC10375142 DOI: 10.1002/advs.202300952] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 04/18/2023] [Indexed: 05/15/2023]
Abstract
Two-dimensional transition metal dichalcogenides (2D TMDs) present promising applications in various fields such as electronics, optoelectronics, memory devices, batteries, superconductors, and hydrogen evolution reactions due to their regulable energy band structures and unique properties. For emerging spintronics applications, materials with excellent room-temperature ferromagnetism are required. Although most transition metal compounds do not possess room-temperature ferromagnetism on their own, they are widely modified by researchers using the emerging strategies to engineer or modulate their intrinsic properties. This paper reviews recent enhancement approaches to induce magnetism in 2D TMDs, mainly using doping, vacancy defects, composite of heterostructures, phase modulation, and adsorption, and also by electron irradiation induction, O plasma treatment, etc. On this basis, the produced effects of these methods for the introduction of magnetism into 2D TMDs are compressively summarized and constructively discussed. For perspective, research on magnetic doping techniques for 2D TMDs materials should be directed toward more reliable and efficient directions, such as exploring advanced design strategies to combine dilute magnetic semiconductors, antiferromagnetic semiconductors, and superconductors to develop new types of heterojunctions; and advancing experimentation strategies to fabricate the designed materials and enable their functionalities with simultaneously pursuing the upscalable growth methods for high-quality monolayers to multilayers.
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Affiliation(s)
- Fan Yang
- School of Metallurgy Engineering, State Local Joint Engineering Research Center for Functional Materials Processing, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Ping Hu
- School of Metallurgy Engineering, State Local Joint Engineering Research Center for Functional Materials Processing, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Fairy Fan Yang
- School of Metallurgy Engineering, State Local Joint Engineering Research Center for Functional Materials Processing, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Bo Chen
- School of Metallurgy Engineering, State Local Joint Engineering Research Center for Functional Materials Processing, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Fei Yin
- School of Metallurgy Engineering, State Local Joint Engineering Research Center for Functional Materials Processing, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Ruiyan Sun
- School of Metallurgy Engineering, State Local Joint Engineering Research Center for Functional Materials Processing, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Ke Hao
- School of Metallurgy Engineering, State Local Joint Engineering Research Center for Functional Materials Processing, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Fei Zhu
- School of Metallurgy Engineering, State Local Joint Engineering Research Center for Functional Materials Processing, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Kuaishe Wang
- School of Metallurgy Engineering, State Local Joint Engineering Research Center for Functional Materials Processing, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Zongyou Yin
- Research School of Chemistry, The Australian National University, Canberra, ACT 2601, Australia
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4
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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: 2] [Impact Index Per Article: 2.0] [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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5
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Wu C, Zhao Y, Zhang G, Liu C. Giant thermal switching in ferromagnetic VSe 2 with programmable switching temperature. NANOSCALE HORIZONS 2023; 8:202-210. [PMID: 36484168 DOI: 10.1039/d2nh00429a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Active and reversible modulation of thermal conductivity can realize efficient heat energy management in many applications such as thermoelectrics. Using first-principles calculations, this study reports a giant thermal switching ratio of 12, much higher than previously reported values, in monolayer 2H-VSe2 above room temperature. Detailed analysis indicates that the high thermal switching ratio is dominated by the ferromagnetic ordering induced phonon bandgap, which significantly suppresses the phonon-phonon scattering phase space across the entire vibration spectrum. The thermal switching in bulk 2H-VSe2 is also investigated and the thermal switching ratio reaches 9.2 at the magnetic transition temperature. Both the phonon-phonon scattering space phase and phonon anharmonicity are responsible for the 9.2-fold thermal switching. This study advances the understanding of heat energy transport in two-dimensional ferromagnets, and also provides new insight into heat energy control and conversion.
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Affiliation(s)
- Chao Wu
- Micro- and Nano-scale Thermal Measurement and Thermal Management Laboratory, School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, 210023, P. R. China.
- Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing, 211100, P. R. China
| | - Yunshan Zhao
- NNU-SULI Thermal Energy Research Center (NSTER) & Center for Quantum Transport and Thermal Energy Science (CQTES), School of Physics and Technology, Nanjing Normal University, Nanjing 210023, P. R. China
| | - Gang Zhang
- Institute of High Performance Computing, Agency for Science, Technology and Research, 138632, Singapore.
| | - Chenhan Liu
- Micro- and Nano-scale Thermal Measurement and Thermal Management Laboratory, School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, 210023, P. R. China.
- Jiangsu Key Laboratory for Numerical Simulation of Large-Scale Complex Systems, Nanjing Normal University, Nanjing, 210023, P. R. China
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6
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You J, Pan J, Shang SL, Xu X, Liu Z, Li J, Liu H, Kang T, Xu M, Li S, Kong D, Wang W, Gao Z, Zhou X, Zhai T, Liu ZK, Kim JK, Luo Z. Salt-Assisted Selective Growth of H-phase Monolayer VSe 2 with Apparent Hole Transport Behavior. NANO LETTERS 2022; 22:10167-10175. [PMID: 36475688 DOI: 10.1021/acs.nanolett.2c04133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Vanadium diselenide (VSe2) exhibits versatile electronic and magnetic properties in the trigonal prismatic (H-) and octahedral (T-) phases. Compared to the metallic T-phase, the H-phase with a tunable semiconductor property is predicted to be a ferrovalley material with spontaneous valley polarization. Herein we report an epitaxial growth of the monolayer 2D VSe2 on a mica substrate via the chemical vapor deposition (CVD) method by introducing salt in the precursor. Our first-principles calculations suggest that the monolayer H-phase VSe2 with a large lateral size is thermodynamically favorable. The honeycomb-like structure and the broken symmetry are directly observed by spherical aberration-corrected scanning transmission electron microscopy (STEM) and confirmed by giant second harmonic generation (SHG) intensity. The p-type transport behavior is further evidenced by the temperature-dependent resistance and field-effect device study. The present work introduces a new phase-stable 2D transition metal dichalcogenide, opening the prospect of novel electronic and spintronics device design.
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Affiliation(s)
- Jiawen You
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong999777, P. R. China
| | - Jie Pan
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong999777, P. R. China
| | - Shun-Li Shang
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania16802, United States
| | - Xiang Xu
- School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan430074, P. R. China
| | - Zhenjing Liu
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong999777, P. R. China
| | - Jingwei Li
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong999777, P. R. China
| | - Hongwei Liu
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong999777, P. R. China
| | - Ting Kang
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong999777, P. R. China
| | - Mengyang Xu
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong999777, P. R. China
| | - Shaobo Li
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong999777, P. R. China
- State Key Laboratory of Luminescent Materials and Devices, Department of Electronic Materials, School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Deqi Kong
- State Key Laboratory of Luminescent Materials and Devices, Department of Electronic Materials, School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Wenliang Wang
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong999777, P. R. China
- State Key Laboratory of Luminescent Materials and Devices, Department of Electronic Materials, School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Zhaoli Gao
- Department of Biomedical Engineering, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong999777, P. R. China
- CUHK Shenzhen Research Institute, No.10, second, Yuexing Road, Nanshan, Shenzhen518057, P. R. China
| | - Xing Zhou
- School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan430074, P. R. China
| | - Tianyou Zhai
- School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan430074, P. R. China
| | - Zi-Kui Liu
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania16802, United States
| | - Jang-Kyo Kim
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong999777, P. R. China
| | - Zhengtang Luo
- Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong999777, P. R. China
- The Hong Kong University of Science and Technology Shenzhen Research Institute, No. 9 Yuexing first RD, South Area Hi-tech Park, Nanshan, Shenzhen518057, China
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7
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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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8
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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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9
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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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10
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Najafi L, Oropesa-Nuñez R, Bellani S, Martín-García B, Pasquale L, Serri M, Drago F, Luxa J, Sofer Z, Sedmidubský D, Brescia R, Lauciello S, Zappia MI, Shinde DV, Manna L, Bonaccorso F. Topochemical Transformation of Two-Dimensional VSe 2 into Metallic Nonlayered VO 2 for Water Splitting Reactions in Acidic and Alkaline Media. ACS NANO 2022; 16:351-367. [PMID: 34939404 DOI: 10.1021/acsnano.1c06662] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The engineering of the structural and morphological properties of nanomaterials is a fundamental aspect to attain desired performance in energy storage/conversion systems and multifunctional composites. We report the synthesis of room temperature-stable metallic rutile VO2 (VO2 (R)) nanosheets by topochemically transforming liquid-phase exfoliated VSe2 in a reductive Ar-H2 atmosphere. The as-produced VO2 (R) represents an example of two-dimensional (2D) nonlayered materials, whose bulk counterparts do not have a layered structure composed by layers held together by van der Waals force or electrostatic forces between charged layers and counterbalancing ions amid them. By pretreating the VSe2 nanosheets by O2 plasma, the resulting 2D VO2 (R) nanosheets exhibit a porous morphology that increases the material specific surface area while introducing defective sites. The as-synthesized porous (holey)-VO2 (R) nanosheets are investigated as metallic catalysts for the water splitting reactions in both acidic and alkaline media, reaching a maximum mass activity of 972.3 A g-1 at -0.300 V vs RHE for the hydrogen evolution reaction (HER) in 0.5 M H2SO4 (faradaic efficiency = 100%, overpotential for the HER at 10 mA cm-2 = 0.184 V) and a mass activity (calculated for a non 100% faradaic efficiency) of 745.9 A g-1 at +1.580 V vs RHE for the oxygen evolution reaction (OER) in 1 M KOH (overpotential for the OER at 10 mA cm-2 = 0.209 V). By demonstrating proof-of-concept electrolyzers, our results show the possibility to synthesize special material phases through topochemical conversion of 2D materials for advanced energy-related applications.
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Affiliation(s)
- Leyla Najafi
- BeDimensional S.p.A., Via Lungotorrente Secca 30R, 16163 Genova, Italy
- Graphene Labs, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Reinier Oropesa-Nuñez
- Department of Material Science and Engineering, Uppsala University, Box 35, 75103 Uppsala, Sweden
| | - Sebastiano Bellani
- BeDimensional S.p.A., Via Lungotorrente Secca 30R, 16163 Genova, Italy
- Graphene Labs, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | | | - Lea Pasquale
- Materials Characterization Facility, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Michele Serri
- Graphene Labs, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Filippo Drago
- Nanochemistry Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Jan Luxa
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Zdeněk Sofer
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - David Sedmidubský
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Rosaria Brescia
- Electron Microscopy Facility, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Simone Lauciello
- Electron Microscopy Facility, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Marilena I Zappia
- BeDimensional S.p.A., Via Lungotorrente Secca 30R, 16163 Genova, Italy
| | - Dipak V Shinde
- Nanochemistry Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Liberato Manna
- Nanochemistry Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Francesco Bonaccorso
- BeDimensional S.p.A., Via Lungotorrente Secca 30R, 16163 Genova, Italy
- Graphene Labs, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
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11
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Wang X, Li D, Li Z, Wu C, Che CM, Chen G, Cui X. Ferromagnetism in 2D Vanadium Diselenide. ACS NANO 2021; 15:16236-16241. [PMID: 34581581 DOI: 10.1021/acsnano.1c05232] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two-dimensional (2D) van der Waals ferromagnets carry the promise of ultimately miniature spintronics and information storage devices. Among the 2D ferromagnets, all inherit the magnetic ordering from their bulk ancestors. Here we report a 2D ferromagnetic semiconductor at room temperature, 2H-phase vanadium diselenide (VSe2), which shows ferromagnetic at the 2D form only. This 2D ferromagnetic semiconductor manifests an enhanced magnetic ordering owing to structural anisotropy at the 2D limit.
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Affiliation(s)
- Xiong Wang
- Physics Department, University of Hong Kong, Hong Kong 999077, People's Republic of China
| | - Dian Li
- Physics Department, University of Hong Kong, Hong Kong 999077, People's Republic of China
| | - Zejun Li
- Hefei National Laboratory for Physical Sciences at the Microscale, CAS Center for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Changzheng Wu
- Hefei National Laboratory for Physical Sciences at the Microscale, CAS Center for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Chi-Ming Che
- Department of Chemistry, State Key Laboratory of Synthetic Chemistry, HKU-CAS Joint Laboratory on New Materials, The University of Hong Kong, Pokfulam Road, Hong Kong 999077, People's Republic of China
| | - Gang Chen
- Physics Department, University of Hong Kong, Hong Kong 999077, People's Republic of China
| | - Xiaodong Cui
- Physics Department, University of Hong Kong, Hong Kong 999077, People's Republic of China
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12
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Topological Phase and Quantum Anomalous Hall Effect in Ferromagnetic Transition-Metal Dichalcogenides Monolayer 1T-VSe2. NANOMATERIALS 2021; 11:nano11081998. [PMID: 34443830 PMCID: PMC8401610 DOI: 10.3390/nano11081998] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/04/2022]
Abstract
Magnetic two-dimensional (2D) van der Waals materials have attracted tremendous attention because of their high potential in spintronics. In particular, the quantum anomalous Hall (QAH) effect in magnetic 2D layers shows a very promising prospect for hosting Majorana zero modes at the topologically protected edge states in proximity to superconductors. However, the QAH effect has not yet been experimentally realized in monolayer systems to date. In this work, we study the electronic structures and topological properties of the 2D ferromagnetic transition-metal dichalcogenides (TMD) monolayer 1T−VSe2 by first-principles calculations with the Heyd–Scuseria–Ernzerhof (HSE) functional. We find that the spin-orbit coupling (SOC) opens a continuous band gap at the magnetic Weyl-like crossing point hosting the quantum anomalous Hall effect with Chern number C=2. Moreover, we demonstrate the topologically protected edge states and intrinsic (spin) Hall conductivity in this magnetic 2D TMD system. Our results indicate that 1T−VSe2 monolayer serves as a stoichiometric quantum anomalous Hall material.
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13
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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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