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Chang Y, Zhang Z, Deng L, Wu Y, Zhang X. Ferrovalley and Quantum Anomalous Hall Effect in Janus TiTeCl Monolayer. MATERIALS (BASEL, SWITZERLAND) 2024; 17:3331. [PMID: 38998413 PMCID: PMC11243056 DOI: 10.3390/ma17133331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Revised: 06/30/2024] [Accepted: 07/03/2024] [Indexed: 07/14/2024]
Abstract
Ferrovalley materials are garnering significant interest for their potential roles in advancing information processing and enhancing data storage capabilities. This study utilizes first-principles calculations to determine that the Janus monolayer TiTeCl exhibits the properties of a ferrovalley semiconductor. This material demonstrates valley polarization with a notable valley splitting of 80 meV. Additionally, the Berry curvature has been computed across the first Brillouin zone of the monolayer TiTeCl. The research also highlights that topological phase transitions ranging from ferrovalley and half-valley metals to quantum anomalous Hall effect states can occur in monolayer TiTeCl under compressive strains ranging from -1% to 0%. Throughout these strain changes, monolayer TiTeCl maintains its ferromagnetic coupling. These characteristics make monolayer TiTeCl a promising candidate for the development of new valleytronic and topological devices.
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Affiliation(s)
- Yufang Chang
- Public Basic Department, Shenyang Conservatory of Music, Shenyang 110818, China;
| | - Zhijun Zhang
- School of Electrical and Automation Engineering, Liaoning Institute of Science and Technology, Benxi 117004, China;
| | - Li Deng
- School of Material Science and Engineering, Northeastern University, Shenyang 110819, China; (L.D.); (Y.W.)
| | - Yanzhao Wu
- School of Material Science and Engineering, Northeastern University, Shenyang 110819, China; (L.D.); (Y.W.)
| | - Xianmin Zhang
- School of Material Science and Engineering, Northeastern University, Shenyang 110819, China; (L.D.); (Y.W.)
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Liu Z, Zhou B, Wang X. Two-dimensional multiferroic RuClF/AgBiP 2S 6 van der Waals heterostructures with valley splitting properties and controllable magnetic anisotropy. Phys Chem Chem Phys 2024; 26:17869-17881. [PMID: 38887794 DOI: 10.1039/d4cp01059k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
The investigation of new properties in two-dimensional (2D) multiferroic heterostructures is significant. In this work, the electronic properties and magnetic anisotropy energies (MAEs) of 2D multiferroic RuClF/AgBiP2S6 van der Waals (vdW) heterostructures are systematically studied by first principles calculations based on density functional theory (DFT). The Hubbard on-site Coulomb parameter (U) of Ru atoms is necessary to account for the strong correlation among the three-dimensional electrons of Ru. RuClF/AgBiP2S6 heterostructures in different polarizations (RuClF/AgBiP2S6-P↑ and RuClF/AgBiP2S6-P↓) are ferromagnetic semiconductors with stable structures. Valley polarizations are present in the band structures of RuClF/AgBiP2S6 heterostructures with spin-orbit coupling (SOC), the valley splitting energies of which are 279 meV and 263 meV, respectively. The MAEs of RuClF/AgBiP2S6 heterostructures indicate perpendicular magnetic anisotropy (PMA), which are primarily attributed to the differences in matrix elements within Ru (dyz, dz2) orbitals. In addition, valley splittings and MAEs of RuClF/AgBiP2S6 heterostructures are modified at different biaxial strains. Specifically, the highest valley splittings are 283 meV and 287 meV at ε = 2%, while they disappear at ε = -6%. The PMA of RuClF/AgBiP2S6-P↑ is gradually decreased at biaxial strains of -6% to 2%, and MAE is transformed into in-plane magnetic anisotropy (IMA) at ε = 4%. RuClF/AgBiP2S6-P↓ maintains PMA at different strains. The study of non-volatile electrical control of valley splitting phenomena in multiferroic RuClF/AgBiP2S6 heterostructures is crucial in the field of valleytronic devices, which has important theoretical significance.
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Affiliation(s)
- Ziyu Liu
- Tianjin Key Laboratory of Film Electronic & Communicate Devices, School of Integrated Circuit Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
| | - Baozeng Zhou
- Tianjin Key Laboratory of Film Electronic & Communicate Devices, School of Integrated Circuit Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
| | - Xiaocha Wang
- Tianjin Key Laboratory of Film Electronic & Communicate Devices, School of Integrated Circuit Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
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Liu MY, Li GQ, He Y, Xiong K. Defect effects on the electronic, valley, and magnetic properties of the two-dimensional ferrovalley material VSi 2N 4. Dalton Trans 2024; 53:10603-10617. [PMID: 38855983 DOI: 10.1039/d4dt00856a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Due to their novel spin and valley properties, two-dimensional (2D) ferrovalley materials are expected to be promising candidates for next-generation spintronic and valleytronic devices. However, they are subject to various defects in practical applications. Therefore, the electronic, valley, and magnetic properties may be modified in the presence of the defects. In this work, utilizing first-principles calculations, we systematically studied the effects of defects on the electronic, valley, and magnetic properties of the 2D ferrovalley material VSi2N4. It has been found that C doping, O doping, and N vacancies result in the half-metallic feature, Si vacancies result in the metallic feature, and V vacancies result in a bipolar gapless semiconductor. These defect-induced electronic properties can be effectively tuned by changing defect concentration and layer thickness. Since the impurity bands do not affect the K and K' valleys, valley polarization is well maintained in O-doped and N-defective systems. Importantly, these defects play a crucial role in modifying the magnetic properties of the pristine VSi2N4, especially the magnitude of local magnetic moments and the magnetic anisotropy energy. Detailed analysis of the density of states demonstrates that the variations of the total magnetic moment and magnetic anisotropy energy with biaxial strain are determined by the electronic states near the Fermi level rather than the type of defect, which provides a new understanding of the effects of defects on the magnetic properties of 2D materials. Moreover, the layer thickness can affect the magnetic coupling between defects and surrounding V atoms. Our results offer insight into the electronic, valley, and magnetic properties of VSi2N4 in the presence of various point defects.
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Affiliation(s)
- Ming-Yang Liu
- Department of Physics and Electronic Science, Chuxiong Normal University, Chuxiong 675000, P. R. China.
| | - Guang-Qiang Li
- Department of Physics and Electronic Science, Chuxiong Normal University, Chuxiong 675000, P. R. China.
| | - Yao He
- Department of Physics, Yunnan University, Kunming 650091, P. R. China
| | - Kai Xiong
- Materials Genome Institute, School of Materials and Energy, Yunnan University, Kunming 650091, P. R. China
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Fan G, Wu Y, Tong J, Deng L, Yin X, Tian F, Zhang X. Influence of electronic correlation on the valley and topological properties of VSiGeP 4 monolayer. Phys Chem Chem Phys 2024; 26:9628-9635. [PMID: 38466239 DOI: 10.1039/d3cp04739c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Valley is used as a new degree of freedom for information encoding and storage. In this work, the valley and topological properties of the VSiGeP4 monolayer were studied by adjusting the U value based on first-principles calculations. The VSiGeP4 monolayer remains in a ferromagnetic ground state regardless of the change in the U value. The magnetic anisotropy of the VSiGeP4 monolayer is initially in-plane, and then turns out-of-plane with the increase in the U value. Moreover, a topological phase transition is observed in the present VSiGeP4 monolayer with the increase in U value from 0 to 3 eV, i.e., the VSiGeP4 monolayer behaves as a bipolar magnetic semiconductor, a ferrovalley semiconductor, a half-valley metal characteristic, and a quantum anomalous Hall state. The mechanism of the topological phase transition behavior of the VSiGeP4 monolayer was analyzed. It was found that the variation in U values would change the strength of the electronic correlation effect, resulting in the valley and topological properties. In addition, carrier doping was studied to design a valleytronic device using this VSiGeP4 monolayer. By doping 0.05 electrons per f.u., the VSiGeP4 monolayer with a U value of 3 eV exhibits 100% spin polarization. This study indicates that the VSiGeP4 monolayer has potential applications in spintronic, valleytronic, and topological electronic nanodevices.
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Affiliation(s)
- Guangxin Fan
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, China.
| | - Yanzhao Wu
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, China.
| | - Junwei Tong
- Department of Physics, Freie Universität Berlin, Berlin 14195, Germany
| | - Li Deng
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, China.
| | - Xiang Yin
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, China.
| | - Fubo Tian
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Xianmin Zhang
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, China.
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Liu Z, Zhou B, Wang X, Mi W. Band inversion and switchable magnetic properties of two-dimensional RuClF/WSe 2 van der Waals heterostructures. Phys Chem Chem Phys 2024; 26:1135-1147. [PMID: 38099407 DOI: 10.1039/d3cp05545k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Two-dimensional (2D) van der Waals (vdW) heterostructures have potential applications in new low-dimensional spintronic devices owing to their unique electronic properties and magnetic anisotropy energies (MAEs). The electronic structures and magnetic properties of RuClF/WSe2 heterostructure are calculated using first-principles calculations. The most stable RuClF/WSe2 heterostructure is selected for property analysis. RuClF/WSe2 heterostructure has half-metallicity. Considering spin-orbit coupling (SOC), band inversion is present in the RuClF/WSe2 heterostructure, which is also demonstrated by the weight of the energy contributions. The local density of states (LDOS) of the edge states can provide strong evidence that the RuClF/WSe2 heterostructure has topological properties. The MAE of RuClF/WSe2 heterostructure is in-plane magnetic anisotropy (IMA), which mainly originates from the contribution of matrix element difference in Ru (dxy, dx2-y2) orbitals. The electronic properties and MAE of RuClF/WSe2 heterostructure can be regulated by biaxial strains and electric fields. The band inversion phenomenon is enhanced at electric fields in the opposite direction, which is also modified at different biaxial strains. However, the band inversion phenomenon disappears at the biaxial strains of 6% and an electric field of 0.5 V Å-1. The MAE of RuClF/WSe2 heterostructure is transformed from IMA into perpendicular magnetic anisotropy (PMA) at certain compressive strains and positively directed electric fields. The above results indicate that the RuClF/WSe2 heterostructure has potential applications in spintronic devices.
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Affiliation(s)
- Ziyu Liu
- Tianjin Key Laboratory of Film Electronic & Communicate Devices, School of Integrated Circuit Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
| | - Baozeng Zhou
- Tianjin Key Laboratory of Film Electronic & Communicate Devices, School of Integrated Circuit Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
| | - Xiaocha Wang
- Tianjin Key Laboratory of Film Electronic & Communicate Devices, School of Integrated Circuit Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
| | - Wenbo Mi
- Department of Applied Physics, School of Science, Tianjin University, Tianjin 300354, China.
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Li YQ, Zhang X, Shang X, He QW, Tang DS, Wang XC, Duan CG. Magnetic and Ferroelectric Manipulation of Valley Physics in Janus Piezoelectric Materials. NANO LETTERS 2023; 23:10013-10020. [PMID: 37856232 DOI: 10.1021/acs.nanolett.3c03238] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
The realization of multiferroic materials offers the possibility of multifunctional electronic device design. However, the coupling between the multiferroicity and piezoelectricity in Janus materials is rarely reported. In this study, we propose a mechanism for manipulating valley physics by magnetization reversing and ferroelectric switching in multiferroic and piezoelectric material. The ferromagnetic VSiGeP4 monolayer exhibits a large valley polarization up to 100 meV, which can be effectively operated by reversing magnetization. Interestingly, the antiferromagnetic VSiGeP4 bilayers with AB and BA stacking configurations allow the coexistence of valley polarization and ferroelectricity, supporting the proposed strategy for manipulating valley physics via ferroelectric switching and interlayer sliding. In addition, the VSiGeP4 monolayer contains remarkable tunable piezoelectricity regulated by electron correlation U. This study proposes a feasible idea for regulating valley polarization and a general design idea for multifunctional devices with multiferroic and piezoelectric properties, facilitating the miniaturization and integration of nanodevices.
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Affiliation(s)
- Yun-Qin Li
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science and Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai 200241, China
| | - Xian Zhang
- Henan Key Laboratory of Photoelectric Energy Storage Materials and Applications, School of Physics and Engineering, Henan University of Science and Technology, Luoyang 471023, China
| | - Xiao Shang
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
| | - Qi-Wen He
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
| | - Dai-Song Tang
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
| | - Xiao-Chun Wang
- School of Physics Science and Information Technology, Liaocheng University, Liaocheng 252000, China
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
| | - Chun-Gang Duan
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science and Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai 200241, China
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Liu Z, Zhou B, Wang X, Mi W. Two dimensional Janus RuXY (X, Y = Br, Cl, F, I, X ≠ Y) monolayers: ferromagnetic semiconductors with spontaneous valley polarization and tunable magnetic anisotropy. Phys Chem Chem Phys 2023; 25:25146-25156. [PMID: 37712230 DOI: 10.1039/d3cp02916f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/16/2023]
Abstract
Two-dimensional (2D) ferromagnetic (FM) materials with valley polarization are highly desirable for use in valleytronic devices. The 2D Janus materials have fascinating physical properties due to their asymmetrical structures. In this work, the electronic structure and magnetic properties of Janus RuXY (X, Y = Br, Cl, F, I, X ≠ Y) monolayers are systematically studied using first-principles calculations. RuBrCl, RuBrF, and RuClF monolayers are all FM semiconductors. The valley polarization is present in the band structure and this is determined by the spin orbit coupling (SOC). The valley splitting energy of the RuClF monolayer is as large as 204 meV, with a perpendicular magnetic anisotropy (PMA) energy of 1.918 mJ m-2 and a Curie temperature of 316 K. Therefore, spontaneous valley polarization at room temperature will be seen in the RuClF monolayer. The Curie temperature of the RuBrF monolayer is higher than that of the RuClF, but the magnetic anisotropy energy (MAE) is in-plane magnetic anisotropy (IMA). The valley splitting energy of the RuBrCl monolayer is higher and the PMA energy is lower than that of the RuClF monolayer. The Curie temperature was only 197 K. The valley polarization was modulated in the RuXY monolayers at different biaxial strains, during which the semiconductor properties are still maintained. The PMA of the RuClF and RuBrCl monolayers is enhanced by the biaxial compressive strains, which are mainly attributed to the variation of the (dyz, d2z) orbital matrix elements of the Ru atoms. The MAE of the RuBrF monolayer is tuned from IMA into PMA at a biaxial strain of -6%. These results show an example of a 2D Janus ferrovalley material.
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Affiliation(s)
- Ziyu Liu
- Tianjin Key Laboratory of Film Electronic & Communication Devices, School of Integrated Circuit Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
| | - Baozeng Zhou
- Tianjin Key Laboratory of Film Electronic & Communication Devices, School of Integrated Circuit Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
| | - Xiaocha Wang
- Tianjin Key Laboratory of Film Electronic & Communication Devices, School of Integrated Circuit Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
| | - Wenbo Mi
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, School of Science, Tianjin University, Tianjin 300354, China.
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Sheng K, Zhang B, Wang ZY. Piezoelectricity and valley polarization in a semilithiated 2H-TiTe 2 monolayer with near room-temperature ferromagnetism. Phys Chem Chem Phys 2023; 25:23738-23745. [PMID: 37615079 DOI: 10.1039/d3cp02532b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Two-dimensional ferromagnetic semiconductors with coupled valley physics and piezoelectric responses offer unprecedented opportunities to miniaturize low-power multifunctional integrated devices. Prompted by epitaxial fabrication of nonmagnetic 2H-TiTe2 monolayer on the Au(111) substrate, we predict through both density functional theory and Monte Carlo simulations that the semilithiated 2H-TiTe2 monolayer (Li@2H-TiTe2) is a stable near room-temperature semiconducting ferromagnet. Under an out-of-plane magnetization, Li@2H-TiTe2 exhibits a clean valley polarization up to 160 meV in its conduction band and a valley-contrasting Berry curvature due to the broken inversion and time-reversal symmetries, in favor of achievable anomalous valley Hall effect. Alternatively, the simultaneous charge, spin, valley Hall currents can be realized as well in the ferromagnetic system with circularly polarized light. Furthermore, the missing mirror symmetry generates a scarce vertical piezoelectricity as large as 0.89 pm V-1. These findings indicate that asymmetric surface functionalization by Li deposition on the 2H-TiTe2 monolayer opens up a vital avenue to predesign superior and tailored multifunctional materials.
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Affiliation(s)
- Kang Sheng
- School of Physical Science and Technology, Southwest University, Chongqing 400715, China
- Chongqing Key Laboratory of Micro-Nano Structure Optoelectronics, Chongqing 400715, China.
| | - Bokai Zhang
- School of Physical Science and Technology, Southwest University, Chongqing 400715, China
- Chongqing Key Laboratory of Micro-Nano Structure Optoelectronics, Chongqing 400715, China.
| | - Zhi-Yong Wang
- School of Physical Science and Technology, Southwest University, Chongqing 400715, China
- Chongqing Key Laboratory of Micro-Nano Structure Optoelectronics, Chongqing 400715, China.
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