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Yao T, Qubie WL, Kumar P, Bai X, Hu S, Xue D, Zhang J. Critical behaviors of van der Waals itinerant ferromagnet Fe 3.8GaTe 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:345801. [PMID: 38759671 DOI: 10.1088/1361-648x/ad4d48] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 05/17/2024] [Indexed: 05/19/2024]
Abstract
The critical behavior of the van der Waals ferromagnet Fe3.8GaTe2was systematically studied through measurements of isothermal magnetization, with the magnetic field applied along thec-axis. Fe3.8GaTe2undergoes a non-continuous paramagnetic to ferromagnetic phase transition at the Curie temperatureTc∼ 355 K. A comprehensive analysis of isotherms aroundTcutilizing the modified Arrott diagram, the Kouvel-Fisher method, the Widom scaling law, and the critical isotherm analysis yielded the critical exponent ofβ= 0.411,γ= 1.246, andδ= 3.99. These critical exponents are found to be self-consistent and align well with the scaling equation at high magnetic fields, underscoring the reliability and intrinsic nature of these parameters. However, the low-field data deviates from the scaling relation, exhibiting a vertical trend whenT
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Affiliation(s)
- Tianyang Yao
- School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - W L Qubie
- School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - Pushpendra Kumar
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Xu Bai
- School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - Shixin Hu
- School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - Desheng Xue
- School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - Junli Zhang
- School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, People's Republic of China
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2
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Stepanova AV, Mironov AV, Bogach AV, Azarevich AN, Presniakov IA, Sobolev AV, Pankratov DA, Zayakhanov VA, Starchikov SS, Verchenko VY, Shevelkov AV. Bulk ferromagnetism in cleavable van der Waals telluride NbFeTe 2. Chem Commun (Camb) 2024; 60:5518-5521. [PMID: 38693880 DOI: 10.1039/d4cc01160k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2024]
Abstract
A van der Waals telluride, NbFeTe2, has been synthesized using chemical vapor transport reactions. The optimized synthetic conditions yield high-quality single crystals with a novel monoclinic crystal structure. Monoclinic NbFeTe2 demonstrates a (100) cleavage plane, bulk ferromagnetism below 87 K, and a metallic ground state-the necessary prerequisites for needed spintronics technologies.
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Affiliation(s)
- Anna V Stepanova
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
| | - Andrei V Mironov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
| | - Alexey V Bogach
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Andrey N Azarevich
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Igor A Presniakov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
- MSU-BIT University, Shenzhen, 517182 Guangdong Province, P. R. China
| | - Alexey V Sobolev
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
- MSU-BIT University, Shenzhen, 517182 Guangdong Province, P. R. China
| | - Denis A Pankratov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
| | | | | | - Valeriy Yu Verchenko
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
| | - Andrei V Shevelkov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
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3
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Eguchi R, Sekhar H, Kimura K, Masai H, Happo N, Ikeda M, Yamamoto Y, Utsumi M, Goto H, Takabayashi Y, Tajiri H, Hayashi K, Kubozono Y. Superstructure of Fe 5-xGeTe 2 Determined by Te K-Edge Extended X-ray Absorption Fine Structure and Te Kα X-ray Fluorescence Holography. ACS OMEGA 2024; 9:21287-21297. [PMID: 38764676 PMCID: PMC11097380 DOI: 10.1021/acsomega.4c01395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 04/12/2024] [Accepted: 04/19/2024] [Indexed: 05/21/2024]
Abstract
The local structure of the two-dimensional van der Waals material, Fe5-xGeTe2, which exhibits unique structural/magnetic phase transitions, was investigated by Te K-edge extended X-ray absorption fine structure (EXAFS) and Te Kα X-ray fluorescence holography (XFH) over a wide temperature range. The formation of a trimer of Te atoms at low temperatures has been fully explored using these methods. An increase in the Te-Fe distance at approximately 150 K was suggested by EXAFS and presumably indicates the formation of a Te trimer. Moreover, XFH displayed clear atomic images of Te atoms. Additionally, the distance between the Te atoms shortened, as confirmed from the atomic images reconstructed from XFH, indicating the formation of a trimer of Te atoms, i.e., a charge-ordered superstructure. Furthermore, Te Kα XFH provided unambiguous atomic images of Fe atoms occupying the Fe1 site; the images were not clearly observed in the Ge Kα XFH that was previously reported because of the low occupancy of Fe and Ge atoms. In this study, EXAFS and XFH clearly showed the local structure around the Te atom; in particular, the formation of Te trimers caused by charge-ordered phase transitions was clearly confirmed. The charge-ordered phase transition is fully discussed based on the structural variation at low temperatures, as established from EXAFS and XFH.
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Affiliation(s)
- Ritsuko Eguchi
- Research
Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Halubai Sekhar
- Department
of Physical Science and Technology, Nagoya
Institute of Technology, Nagoya 466-8585, Japan
| | - Koji Kimura
- Department
of Physical Science and Technology, Nagoya
Institute of Technology, Nagoya 466-8585, Japan
- Research
Center for Advanced Measurement and Characterization, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
- Japan
Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo 679-5198, Japan
| | - Hirokazu Masai
- Department
of Materials and Chemistry, National Institute
of Advanced Industrial Science and Technology (AIST), Osaka 563-8577, Japan
| | - Naohisa Happo
- Graduate
School of Information Sciences, Hiroshima
City University, Hiroshima 731-3194, Japan
| | - Mitsuki Ikeda
- Research
Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Yuki Yamamoto
- Research
Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Masaki Utsumi
- Research
Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Hidenori Goto
- Research
Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Yasuhiro Takabayashi
- Department
of Physical Science and Technology, Nagoya
Institute of Technology, Nagoya 466-8585, Japan
| | - Hiroo Tajiri
- Japan
Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo 679-5198, Japan
| | - Koichi Hayashi
- Department
of Physical Science and Technology, Nagoya
Institute of Technology, Nagoya 466-8585, Japan
- Japan
Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo 679-5198, Japan
| | - Yoshihiro Kubozono
- Research
Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
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4
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Eguchi R, Ikeda M, Yamamoto Y, Goto H, Happo N, Kimura K, Hayashi K, Kubozono Y. Observation of the Superstructure in Fe 5-xGeTe 2 by X-ray Fluorescence Holography. Inorg Chem 2024; 63:947-953. [PMID: 38157480 DOI: 10.1021/acs.inorgchem.3c02254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Fe5-xGeTe2 is a two-dimensional van der Waals material that exhibits ferromagnetic order with a high Curie temperature (TC) of around room temperature. In addition to TC, two magnetic transitions occur with decreasing temperature, and a charge-ordered state is observed at low temperatures. We employed Ge Kα X-ray fluorescence holography (XFH) for Fe5-xGeTe2 to directly investigate the local structure in the charge-ordered state, i.e., the 3 × 3 superstructure. The Ge Kα XFH results revealed local atomic structures around the Ge atom, thus clarifying the simultaneous locations and arrangements of the Te, Fe, and Ge atoms. The atomic positions relative to the Ge atom are useful for understanding the coexistence of the ideal 1 × 1 structure and 3 × 3 superstructure found in the charge-ordered state.
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Affiliation(s)
- Ritsuko Eguchi
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Mitsuki Ikeda
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Yuki Yamamoto
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Hidenori Goto
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Naohisa Happo
- Graduate School of Information Sciences, Hiroshima City University, Hiroshima 731-3194, Japan
| | - Koji Kimura
- Department of Physical Science and Technology, Nagoya Institute of Technology, Nagoya 466-8585, Japan
- Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, Tsukuba 305-0047, Japan
| | - Koichi Hayashi
- Department of Physical Science and Technology, Nagoya Institute of Technology, Nagoya 466-8585, Japan
| | - Yoshihiro Kubozono
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
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5
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Lee JE, Yan S, Oh S, Hwang J, Denlinger JD, Hwang C, Lei H, Mo SK, Park SY, Ryu H. Electronic Structure of Above-Room-Temperature van der Waals Ferromagnet Fe 3GaTe 2. NANO LETTERS 2023; 23:11526-11532. [PMID: 38079244 DOI: 10.1021/acs.nanolett.3c03203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Fe3GaTe2, a recently discovered van der Waals ferromagnet, demonstrates intrinsic ferromagnetism above room temperature, necessitating a comprehensive investigation of the microscopic origins of its high Curie temperature (TC). In this study, we reveal the electronic structure of Fe3GaTe2 in its ferromagnetic ground state using angle-resolved photoemission spectroscopy and density functional theory calculations. Our results establish a consistent correspondence between the measured band structure and theoretical calculations, underscoring the significant contributions of the Heisenberg exchange interaction (Jex) and magnetic anisotropy energy to the development of the high-TC ferromagnetic ordering in Fe3GaTe2. Intriguingly, we observe substantial modifications to these crucial driving factors through doping, which we attribute to alterations in multiple spin-splitting bands near the Fermi level. These findings provide valuable insights into the underlying electronic structure and its correlation with the emergence of high-TC ferromagnetic ordering in Fe3GaTe2.
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Affiliation(s)
- Ji-Eun Lee
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Max Planck POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Shaohua Yan
- Beijing Key Laboratory of Optoelectronic Functional Materials MicroNano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing 100872, China
| | - Sehoon Oh
- Department of Physics and Origin of Matter and Evolution of Galaxies (OMEG) Institute, Soongsil University, Seoul 06978, Korea
| | - Jinwoong Hwang
- Department of Physics, Kangwon National University, Chuncheon 24341, Korea
| | - Jonathan D Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Choongyu Hwang
- Department of Physics, Pusan National University, Busan 46241, Korea
- Quantum Matter Core Facility, Pusan National University, Busan 46241, Korea
| | - Hechang Lei
- Beijing Key Laboratory of Optoelectronic Functional Materials MicroNano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing 100872, China
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Se Young Park
- Department of Physics and Origin of Matter and Evolution of Galaxies (OMEG) Institute, Soongsil University, Seoul 06978, Korea
| | - Hyejin Ryu
- Center for Spintronics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
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6
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Chen J, Wang X, An Y, Gong SJ. Recent progress in 2D bipolar magnetic semiconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 36:083001. [PMID: 37956444 DOI: 10.1088/1361-648x/ad0bff] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 11/13/2023] [Indexed: 11/15/2023]
Abstract
Bipolar magnetic semiconductor (BMS) is a class of magnetic semiconductors, whose valence band maximum and conduction band minimum are fully spin-polarized with opposite spin directions. Due to the special energy band, half-metallicity can be easily obtained in BMS by gate voltage, and the spin polarization can be reversed between spin-up and down when the gate voltage switches from positive to negative. BMSs have great potential applications in spintronic devices, such as the field-effect spin valves, spin filters and spin transistors,etc. With the rapid progress of the two-dimensional (2D) magnetic materials, researchers have identified a series of potential intrinsic 2D BMS materials using high-throughput computational methods. Additionally, methods such as doping, application of external stress, introduction of external fields, stacking of interlayer antiferromagnetic semiconductors, and construction of Janus structures have endowed existing materials with BMS properties. This paper reviews the research progress of 2D BMS. These advancements provide crucial guidance for the design and synthesis of BMS materials and offer innovative pathways for the future development of spintronics.
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Affiliation(s)
- Ju Chen
- Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, People's Republic of China
| | - Xuening Wang
- Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, People's Republic of China
| | - Yipeng An
- School of Physics, Henan Normal University, Xinxiang 453007, People's Republic of China
| | - Shi-Jing Gong
- Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, People's Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 30006, People's Republic of China
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7
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Ren H, Lan M. Progress and Prospects in Metallic Fe xGeTe 2 (3 ≤ x ≤ 7) Ferromagnets. Molecules 2023; 28:7244. [PMID: 37959664 PMCID: PMC10649090 DOI: 10.3390/molecules28217244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/05/2023] [Accepted: 10/21/2023] [Indexed: 11/15/2023] Open
Abstract
Thermal fluctuations in two-dimensional (2D) isotropy systems at non-zero finite temperatures can destroy the long-range (LR) magnetic order due to the mechanisms addressed in the Mermin-Wanger theory. However, the magnetic anisotropy related to spin-orbit coupling (SOC) may stabilize magnetic order in 2D systems. Very recently, 2D FexGeTe2 (3 ≤ x ≤ 7) with a high Curie temperature (TC) has not only undergone significant developments in terms of synthetic methods and the control of ferromagnetism (FM), but is also being actively explored for applications in various devices. In this review, we introduce six experimental methods, ten ferromagnetic modulation strategies, and four spintronic devices for 2D FexGeTe2 materials. In summary, we outline the challenges and potential research directions in this field.
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Affiliation(s)
- Hongtao Ren
- School of Materials Science and Engineering, Liaocheng University, Liaocheng 252000, China
| | - Mu Lan
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China
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8
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Man P, Huang L, Zhao J, Ly TH. Ferroic Phases in Two-Dimensional Materials. Chem Rev 2023; 123:10990-11046. [PMID: 37672768 DOI: 10.1021/acs.chemrev.3c00170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Two-dimensional (2D) ferroics, namely ferroelectric, ferromagnetic, and ferroelastic materials, are attracting rising interest due to their fascinating physical properties and promising functional applications. A variety of 2D ferroic phases, as well as 2D multiferroics and the novel 2D ferrovalleytronics/ferrotoroidics, have been recently predicted by theory, even down to the single atomic layers. Meanwhile, some of them have already been experimentally verified. In addition to the intrinsic 2D ferroics, appropriate stacking, doping, and defects can also artificially regulate the ferroic phases of 2D materials. Correspondingly, ferroic ordering in 2D materials exhibits enormous potential for future high density memory devices, energy conversion devices, and sensing devices, among other applications. In this paper, the recent research progresses on 2D ferroic phases are comprehensively reviewed, with emphasis on chemistry and structural origin of the ferroic properties. In addition, the promising applications of the 2D ferroics for information storage, optoelectronics, and sensing are also briefly discussed. Finally, we envisioned a few possible pathways for the future 2D ferroics research and development. This comprehensive overview on the 2D ferroic phases can provide an atlas for this field and facilitate further exploration of the intriguing new materials and physical phenomena, which will generate tremendous impact on future functional materials and devices.
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Affiliation(s)
- Ping Man
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong 999077, P. R. China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, P. R. China
| | - Lingli Huang
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong 999077, P. R. China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, P. R. China
| | - Jiong Zhao
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong 999077, P. R. China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057, P. R. China
| | - Thuc Hue Ly
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong 999077, P. R. China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, P. R. China
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong 999077, P. R. China
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Liu C, Jiang J, Zhang C, Wang Q, Zhang H, Zheng D, Li Y, Ma Y, Algaidi H, Gao X, Hou Z, Mi W, Liu J, Qiu Z, Zhang X. Controllable Skyrmionic Phase Transition between Néel Skyrmions and Bloch Skyrmionic Bubbles in van der Waals Ferromagnet Fe 3-δ GeTe 2. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2303443. [PMID: 37505392 PMCID: PMC10520623 DOI: 10.1002/advs.202303443] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 07/05/2023] [Indexed: 07/29/2023]
Abstract
The van der Waals (vdW) ferromagnet Fe3-δ GeTe2 has garnered significant research interest as a platform for skyrmionic spin configurations, that is, skyrmions and skyrmionic bubbles. However, despite extensive efforts, the origin of the Dzyaloshinskii-Moriya interaction (DMI) in Fe3-δ GeTe2 remains elusive, making it challenging to acquire these skyrmionic phases in a controlled manner. In this study, it is demonstrated that the Fe content in Fe3-δ GeTe2 has a profound effect on the crystal structure, DMI, and skyrmionic phase. For the first time, a marked increase in Fe atom displacement with decreasing Fe content is observed, transforming the original centrosymmetric crystal structure into a non-centrosymmetric symmetry, leading to a considerable DMI. Additionally, by varying the Fe content and sample thickness, a controllable transition between Néel-type skyrmions and Bloch-type skyrmionic bubbles is achieved, governed by a delicate interplay between dipole-dipole interaction and the DMI. The findings offer novel insights into the variable skyrmionic phases in Fe3-δ GeTe2 and provide the impetus for developing vdW ferromagnet-based spintronic devices.
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Affiliation(s)
- Chen Liu
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Jiawei Jiang
- Tianjin Key Laboratory of Low‐Dimensional Materials Physics and Preparation Technology, School of ScienceTianjin UniversityTianjin300354China
| | - Chenhui Zhang
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Qingping Wang
- College of Electronic Information and AutomationAba Teachers UniversityPixian StreetSichuan623002China
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006China
| | - Huai Zhang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006China
| | - Dongxing Zheng
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Yan Li
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Yinchang Ma
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Hanin Algaidi
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Xingsen Gao
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006China
| | - Zhipeng Hou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006China
| | - Wenbo Mi
- Tianjin Key Laboratory of Low‐Dimensional Materials Physics and Preparation Technology, School of ScienceTianjin UniversityTianjin300354China
| | - Jun‐ming Liu
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006China
- Laboratory of Solid State Microstructures and Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing211102China
| | - Ziqiang Qiu
- Department of PhysicsUniversity of California at BerkeleyBerkeleyCA94720USA
| | - Xixiang Zhang
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
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10
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Dang N, Kozlenko DP, Lis ON, Kichanov SE, Lukin YV, Golosova NO, Savenko BN, Duong D, Phan T, Tran T, Phan M. High Pressure-Driven Magnetic Disorder and Structural Transformation in Fe 3 GeTe 2 : Emergence of a Magnetic Quantum Critical Point. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2206842. [PMID: 36698300 PMCID: PMC10037988 DOI: 10.1002/advs.202206842] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 01/06/2023] [Indexed: 06/17/2023]
Abstract
Among the recently discovered 2D intrinsic van der Waals (vdW) magnets, Fe3 GeTe2 (FGT) has emerged as a strong candidate for spintronics applications, due to its high Curie temperature (130 - 220 K) and magnetic tunability in response to external stimuli (electrical field, light, strain). Theory predicts that the magnetism of FGT can be significantly modulated by an external strain. However, experimental evidence is needed to validate this prediction and understand the underlying mechanism of strain-mediated vdW magnetism in this system. Here, the effects of pressure (0 - 20 GPa) are elucidated on the magnetic and structural properties of Fe3 GeTe2 by means of synchrotron Mössbauer source spectroscopy, X-ray powder diffraction and Raman spectroscopy over a wide temperature range of 10 - 290 K. A strong suppression of ferromagnetic ordering is observed with increasing pressure, and a paramagnetic ground state emerges when pressure exceeds a critical value, PPM ≈ 15 GPa. The anomalous pressure dependence of structural parameters and vibrational modes is observed at PC ≈ 7 GPa and attributed to an isostructural phase transformation. Density functional theory calculations complement these experimental findings. This study highlights pressure as a driving force for magnetic quantum criticality in layered vdW magnetic systems.
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Affiliation(s)
- Ngoc‐Toan Dang
- Institute of Research and DevelopmentDuy Tan UniversityDa Nang550000Vietnam
- Faculty of Environmental and Natural SciencesDuy Tan UniversityDa Nang550000Vietnam
| | | | - Olga N. Lis
- Frank Laboratory of Neutron PhysicsJINRMoscow Reg.Dubna141980Russia
- Kazan Federal UniversityKazan420008Russia
| | | | | | | | - Boris N. Savenko
- Frank Laboratory of Neutron PhysicsJINRMoscow Reg.Dubna141980Russia
| | - Dinh‐Loc Duong
- Center for Integrated Nanostructure PhysicsInstitute for Basic ScienceSuwon16419Republic of Korea
| | - The‐Long Phan
- Faculty of Engineering Physics and NanotechnologyVNU‐University of Engineering and Technology144 Xuan Thuy, Cau GiayHa Noi100000Vietnam
| | - Tuan‐Anh Tran
- Ho Chi Minh City University of Technology and EducationHo Chi Minh700000Vietnam
| | - Manh‐Huong Phan
- Department of PhysicsUniversity of South FloridaTampaFL33620USA
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11
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Koo HJ, Kremer RK, Whangbo MH. High-Spin Orbital Interactions Across van der Waals Gaps Controlling the Interlayer Ferromagnetism in van der Waals Ferromagnets. J Am Chem Soc 2022; 144:16272-16275. [PMID: 36044247 DOI: 10.1021/jacs.2c06741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We examined what interactions control the sign and strength of the interlayer coupling in van der Waals ferromagnets such as Fe3-xGeTe2, Cr2Ge2Te6, CrI3, and VI3 to find that high-spin orbital interactions across the van der Waals gaps are a key to understanding their ferromagnetism. Interlayer ferromagnetic coupling in Fe3-xGeTe2, Cr2Ge2Te6, and CrI3 is governed by the high-spin two-orbital two-electron destabilization, but that in VI3 by the high-spin four-orbital two-electron stabilization. These interactions explain a number of seemingly puzzling observations in van der Waals ferromagnets.
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Affiliation(s)
- Hyun-Joo Koo
- Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Reinhard K Kremer
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Myung-Hwan Whangbo
- Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 02447, Republic of Korea.,Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
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12
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Verchenko VY, Stepanova AV, Bogach AV, Mironov AV, Shevelkov AV. Fe-Rich Ferromagnetic Cleavable Van der Waals Telluride Fe 5AsTe 2. Inorg Chem 2022; 61:9224-9230. [PMID: 35658443 DOI: 10.1021/acs.inorgchem.2c00800] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Transition metal-based layered compounds with van der Waals gaps between the structural layers are a rich source of magnetic materials for spintronic applications. Bulk crystals can be cleaved, providing high-quality two-dimensional nanomaterials, which are promising for the manipulation of spins in spintronic devices and low power quantum logic interfaces. The layered van der Waals telluride Fe5AsTe2 can be synthesized by the high-temperature reaction of elements. In the crystal structure, Fe-rich structural layers with the composition of Fe4.58(4)AsTe2 are separated by the van der Waals gaps with no atoms in the interstitial region. Crystal growth employing chemical vapor transport reactions yields bulk cleavable crystals, which exhibit weak inherent ferromagnetism below the Curie temperature of TC = 48 K. In the ordered state, the magnetization shows a dual-slope behavior in low magnetic fields, indicating the compensated or canted nature of magnetism. Magnetic susceptibility and magnetization measurements reveal perpendicular magnetic anisotropy. The large Rhodes-Wohlfarth ratio of 4.6 indicates the itinerant nature of ferromagnetism in Fe5AsTe2.
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Affiliation(s)
- Valeriy Yu Verchenko
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.,National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia
| | - Anna V Stepanova
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Alexey V Bogach
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Andrei V Mironov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Andrei V Shevelkov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
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13
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Verchenko VY, Kanibolotskiy AV, Bogach AV, Znamenkov KO, Shevelkov AV. Ferromagnetic correlations in the layered van der Waals sulfide FeAl 2S 4. Dalton Trans 2022; 51:8454-8460. [PMID: 35593508 DOI: 10.1039/d2dt00671e] [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
Transition metal-based layered compounds with van der Waals gaps between the adjacent layers are a source of two-dimensional (2D) nanomaterials with nontrivial transport and magnetic properties. 2D ferromagnets, both metals and semiconductors, can be leveraged to produce spin-polarized current in spintronic devices with tailored functionalities. Here, we report on the synthesis, crystal growth, crystal and electronic structure, and magnetic properties of the Fe-based FeAl2S4 layered sulfide. In the crystal structure, Fe and Al atoms mix on octahedral and tetrahedral sites between hexagonal layers of S atoms, which are terminated by the van der Waals gaps. Band structure calculations reveal strong electronic correlations within the semiconducting ground state, which induce ferromagnetism with the magnetic moment of 0.12μB per formula unit for a Hubbard interaction U = 5 eV and Hund's rule coupling J = 0.8 eV. Crystal growth employing chemical vapor transport reactions results in bulk cleavable crystals, which show paramagnetic Curie-Weiss behavior at high temperatures with the Fe2+ magnetic centers. At low temperatures, an anomaly is observed on the magnetic susceptibility curve, below which the magnetization shows ferromagnetic hysteresis, indicating the presence of ferromagnetic correlations in FeAl2S4.
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Affiliation(s)
- Valeriy Yu Verchenko
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia. .,National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia
| | | | - Alexey V Bogach
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia
| | | | - Andrei V Shevelkov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
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14
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Chakraborty A, Srivastava AK, Sharma AK, Gopi AK, Mohseni K, Ernst A, Deniz H, Hazra BK, Das S, Sessi P, Kostanovskiy I, Ma T, Meyerheim HL, Parkin SSP. Magnetic Skyrmions in a Thickness Tunable 2D Ferromagnet from a Defect Driven Dzyaloshinskii-Moriya Interaction. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2108637. [PMID: 35048455 DOI: 10.1002/adma.202108637] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/15/2021] [Indexed: 06/14/2023]
Abstract
There is considerable interest in van der Waals (vdW) materials as potential hosts for chiral skyrmionic spin textures. Of particular interest is the ferromagnetic, metallic compound Fe3 GeTe2 (FGT), which has a comparatively high Curie temperature (150-220 K). Several recent studies have reported the observation of chiral Néel skyrmions in this compound, which is inconsistent with its presumed centrosymmetric structure. Here the observation of Néel type skyrmions in single crystals of FGT via Lorentz transmission electron microscopy (LTEM) is reported. It is shown from detailed X-ray diffraction structure analysis that FGT lacks an inversion symmetry as a result of an asymmetric distribution of Fe vacancies. This vacancy-induced breaking of the inversion symmetry of this compound is a surprising and novel observation and is a prerequisite for a Dzyaloshinskii-Moriya vector exchange interaction which accounts for the chiral Néel skyrmion phase. This phenomenon is likely to be common to many 2D vdW materials and suggests a path to the preparation of many such acentric compounds. Furthermore, it is found that the skyrmion size in FGT is strongly dependent on its thickness: the skyrmion size increases from ≈100 to ≈750 nm as the thickness of the lamella is increased from ≈90 nm to ≈2 µm. This extreme size tunability is a feature common to many low symmetry ferro- and ferri-magnetic compounds.
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Affiliation(s)
- Anirban Chakraborty
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Abhay K Srivastava
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Ankit K Sharma
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Ajesh K Gopi
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Katayoon Mohseni
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Arthur Ernst
- Johannes Kepler University, Altenbergerstrβe 69, Linz, 4040, Austria
| | - Hakan Deniz
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Binoy Krishna Hazra
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Souvik Das
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Paolo Sessi
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Ilya Kostanovskiy
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Tianping Ma
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Holger L Meyerheim
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
| | - Stuart S P Parkin
- Department for Nano-Systems from Ions, Spins, and Electrons (NISE), Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120, Halle(Saale), Germany
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15
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Zhao M, Chen BB, Xi Y, Zhao Y, Xu H, Zhang H, Cheng N, Feng H, Zhuang J, Pan F, Xu X, Hao W, Li W, Zhou S, Dou SX, Du Y. Kondo Holes in the Two-Dimensional Itinerant Ising Ferromagnet Fe 3GeTe 2. NANO LETTERS 2021; 21:6117-6123. [PMID: 34279960 DOI: 10.1021/acs.nanolett.1c01661] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Heavy Fermion (HF) states emerge in correlated quantum materials due to the intriguing interplay between localized magnetic moments and itinerant electrons but rarely appear in 3d-electron systems due to high itinerancy of d-electrons. Here, an anomalous enhancement of Kondo screening is observed at the Kondo hole of local Fe vacancies in Fe3GeTe2 which is a recently discovered 3d-HF system featuring Kondo lattice and two-dimensional itinerant ferromagnetism. An itinerant Kondo-Ising model is established to reproduce the experimental results and provides insight into the competition between Ising ferromagnetism and Kondo screening. Our work explains the microscopic origin of the d-electron HF states in Fe3GeTe2 and inspires future studies of the enriched quantum many-body effects with Kondo holes.
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Affiliation(s)
- Mengting Zhao
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
| | - Bin-Bin Chen
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
| | - Yilian Xi
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
| | - Yanyan Zhao
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024, China
| | - Hang Xu
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
| | - Hongrun Zhang
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
| | - Ningyan Cheng
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, 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, China
| | - Haifeng Feng
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
| | - Jincheng Zhuang
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
| | - Feng Pan
- Research Institute for Frontier Science, Beihang University, Beijing 100191, China
| | - Xun Xu
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
| | - Weichang Hao
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
| | - Wei Li
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
- International Research Institute of Multidisciplinary Science, Beihang University, Beijing 100191, China
| | - Si Zhou
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024, China
| | - Shi Xue Dou
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
| | - Yi Du
- BUAA-UOW Joint Research Centre and School of Physics, Beihang University, Beijing 100191, China
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
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16
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Hopkinson DG, Seki T, Clark N, Chen R, Zou Y, Kimura A, Gorbachev RV, Thomson T, Shibata N, Haigh SJ. Nanometre imaging of Fe 3GeTe 2 ferromagnetic domain walls. NANOTECHNOLOGY 2021; 32:205703. [PMID: 33624615 DOI: 10.1088/1361-6528/abe32b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Fe3GeTe2 is a layered crystal which has recently been shown to maintain its itinerant ferromagnetic properties even when atomically thin. Here, differential phase contrast scanning transmission electron microscopy is used to investigate the domain structure in a Fe3GeTe2 cross-sectional lamella at temperatures ranging from 95 to 250 K and at nanometre spatial resolution. Below the experimentally determined Curie temperature (T C) of 191 K, stripe domains magnetised along 〈0001〉, bounded with 180◦ Bloch type domain walls, are observed, transitioning to mixed Bloch-Néel type where the cross-sectional thickness is reduced below 50 nm. When warming towards T C, these domains undergo slight restructuring towards uniform size, before abruptly fading at T C. Localised loss of ferromagnetic order is seen over time, hypothesised to be a frustration of ferromagnetic order from ambient oxidation and basal cracking, which could enable selective modification of the magnetic properties for device applications.
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Affiliation(s)
- David G Hopkinson
- National Graphene Institute, The University of Manchester, M13 9PL, United Kingdom
- Department of Materials, The University of Manchester, M13 9PL, United Kingdom
| | - Takehito Seki
- Institute of Engineering Innovation, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
| | - Nicholas Clark
- National Graphene Institute, The University of Manchester, M13 9PL, United Kingdom
- Department of Materials, The University of Manchester, M13 9PL, United Kingdom
| | - Runze Chen
- Department of Computer Science, The University of Manchester, M13 9PL, United Kingdom
| | - Yichao Zou
- Department of Materials, The University of Manchester, M13 9PL, United Kingdom
| | - Ayumi Kimura
- Institute of Engineering Innovation, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
| | - Roman V Gorbachev
- National Graphene Institute, The University of Manchester, M13 9PL, United Kingdom
- Department of Physics & Astronomy, The University of Manchester, M13 9PL, United Kingdom
| | - Thomas Thomson
- Department of Computer Science, The University of Manchester, M13 9PL, United Kingdom
| | - Naoya Shibata
- Institute of Engineering Innovation, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramic Center, Atsuta, Nagoya 456-8587, Japan
| | - Sarah J Haigh
- National Graphene Institute, The University of Manchester, M13 9PL, United Kingdom
- Department of Materials, The University of Manchester, M13 9PL, United Kingdom
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17
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Khalaniya RA, Sobolev AV, Verchenko VY, Tsirlin AA, Senyshyn A, Damay F, Presniakov IA, Shevelkov AV. Magnetic structures of Fe 32+δGe 33As 2 and Fe 32+δ'Ge 35-xP x intermetallic compounds: a neutron diffraction and 57Fe Mössbauer spectroscopy study. Dalton Trans 2021; 50:2210-2220. [PMID: 33502418 DOI: 10.1039/d0dt03923c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fe32+δGe33As2 and Fe32+δ'Ge35-xPx are quasi-binary intermetallic compounds that possess a rare variant of intergrowth-type crystal structure, which is a combination of the column shaped Co2Al5 and MgFe6Ge6 structure type blocks. The compounds are antiferromagnets with the Néel temperatures around 125 K. Neutron powder diffraction experiments on the samples with δ≈ 0.1, δ'≈ 0.5 and x≈ 3 reveal commensurate magnetic ordering of low symmetry in both compounds and a non-monotonic change in the intensities of magnetic reflections. On the other hand, temperature dependence of the hyperfine fields obtained from 57Fe Mössbauer spectroscopy indicates a gradual, monotonic increase in local magnetic fields upon cooling. We interpret these results as a spin reorientation within the Co2Al5-type block of the crystal structure, with the possible formation of a non-collinear magnetic order at low temperatures. Between the compounds, the reorientation occurs at significantly different temperatures, however the resulting magnetic structures themselves are similar as well as the average values of the magnetic moments and the hyperfine fields.
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Affiliation(s)
- R A Khalaniya
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia.
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18
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Liu N, Gallaro CM, Shayan K, Mukherjee A, Kim B, Hone J, Vamivakas N, Strauf S. Antiferromagnetic proximity coupling between semiconductor quantum emitters in WSe 2 and van der Waals ferromagnets. NANOSCALE 2021; 13:832-841. [PMID: 33351877 DOI: 10.1039/d0nr06632j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
van der Waals ferromagnets have gained significant interest due to their unique ability to provide magnetic response even at the level of a few monolayers. Particularly in combination with 2D semiconductors, such as the transition metal dichalcogenide WSe2, one can create heterostructures that feature unique magneto-optical response in the exciton emission through the magnetic proximity effect. Here we use 0D quantum emitters in WSe2 to probe for the ferromagnetic response in heterostructures with Fe3GT and Fe5GT ferromagnets through an all-optical read-out technique that does not require electrodes. The spectrally narrow spin-doublet of the WSe2 quantum emitters allowed to fully resolve the hysteretic magneto-response in the exciton emission, revealing the characteristic signature of both ferro- and antiferromagnetic proximity coupling that originates from the interplay among Fe3GT or Fe5GT, a thin surface oxide, and the spin doublets of the quantum emitters. Our work highlights the utility of 0D quantum emitters for probing interface magnetic dipoles in vdW heterostructures with high precision. The observed hysteretic magneto response in the exciton emission of quantum emitters adds further new degrees of freedom for spin and g-factor manipulation of quantum states.
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Affiliation(s)
- Na Liu
- Department of Physics, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA. and Center for Quantum Science and Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA
| | - Cosmo M Gallaro
- Department of Physics, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA. and Center for Quantum Science and Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA
| | - Kamran Shayan
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA and Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA
| | - Arunabh Mukherjee
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA and Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA
| | - Bumho Kim
- Department of Mechanical Engineering, Columbia University, New York 10027, USA
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York 10027, USA
| | - Nick Vamivakas
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA and Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA and Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
| | - Stefan Strauf
- Department of Physics, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA. and Center for Quantum Science and Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA
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19
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Yang S, Zhang T, Jiang C. van der Waals Magnets: Material Family, Detection and Modulation of Magnetism, and Perspective in Spintronics. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2002488. [PMID: 33511010 PMCID: PMC7816723 DOI: 10.1002/advs.202002488] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/09/2020] [Indexed: 06/02/2023]
Abstract
van der Waals (vdW) materials exhibit great potential in spintronics, arising from their excellent spin transportation, large spin-orbit coupling, and high-quality interfaces. The recent discovery of intrinsic vdW antiferromagnets and ferromagnets has laid the foundation for the construction of all-vdW spintronic devices, and enables the study of low-dimensional magnetism, which is of both technical and scientific significance. In this review, several representative families of vdW magnets are introduced, followed by a comprehensive summary of the methods utilized in reading out the magnetic states of vdW magnets. Thereafter, it is shown that various electrical, mechanical, and chemical approaches are employed to modulate the magnetism of vdW magnets. Finally, the perspective of vdW magnets in spintronics is discussed and an outlook of future development direction in this field is also proposed.
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Affiliation(s)
- Shengxue Yang
- School of Materials Science and EngineeringBeihang UniversityBeijing100191P. R. China
| | - Tianle Zhang
- School of Materials Science and EngineeringBeihang UniversityBeijing100191P. R. China
| | - Chengbao Jiang
- School of Materials Science and EngineeringBeihang UniversityBeijing100191P. R. China
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20
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Jang SW, Yoon H, Jeong MY, Ryee S, Kim HS, Han MJ. Origin of ferromagnetism and the effect of doping on Fe 3GeTe 2. NANOSCALE 2020; 12:13501-13506. [PMID: 32555905 DOI: 10.1039/c9nr10171c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recent experimental findings of two dimensional ferromagnetism in Fe3GeTe2, whose critical temperature can reach room temperature by gating, has attracted great research interest. Here we performed elaborate ab initio studies using density functional theory, dynamical mean-field theory and magnetic force response theory. In contrast to the conventional wisdom, it is unambiguously shown that Fe3GeTe2 is not ferromagnetic but is antiferromagnetic, carrying zero net moment in its stoichiometric phase. Fe defect and hole doping are the keys to make this material ferromagnetic as supported by previously disregarded experiments. Furthermore, we found that electron doping also induces the antiferro- to ferro-magnetic transition. It is crucial to understand the notable recent experiments on gate-controlled ferromagnetism. Our results not only reveal the origin of ferromagnetism of this material but also show how it can be manipulated with defects and doping.
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Affiliation(s)
- Seung Woo Jang
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
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21
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Ding B, Li Z, Xu G, Li H, Hou Z, Liu E, Xi X, Xu F, Yao Y, Wang W. Observation of Magnetic Skyrmion Bubbles in a van der Waals Ferromagnet Fe 3GeTe 2. NANO LETTERS 2020; 20:868-873. [PMID: 31869236 DOI: 10.1021/acs.nanolett.9b03453] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Two-dimensional (2D) van der Waals (vdW) magnetic materials have recently been introduced as a new horizon in materials science, and they enable potential applications for next-generation spintronic devices. Here, in this communication, the observations of stable Bloch-type magnetic skyrmions in single crystals of 2D vdW Fe3GeTe2 (FGT) are reported by using in situ Lorentz transmission electron microscopy (TEM). We find the ground-state magnetic stripe domains in FGT transform into skyrmion bubbles when an external magnetic field is applied perpendicularly to the (001) thin plate with temperatures below the Curie temperature TC. Most interestingly, a hexagonal lattice of skyrmion bubbles is obtained via field-cooling manipulation with magnetic field applied along the [001] direction. Owing to their topological stability, the skyrmion bubble lattices are stable to large field-cooling tilted angles and further reproduced by utilizing the micromagnetic simulations. These observations directly demonstrate that the 2D vdW FGT possesses a rich variety of topological spin textures, being of great promise for future applications in the field of spintronics.
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Affiliation(s)
- Bei Ding
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Zefang Li
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Guizhou Xu
- School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Hang Li
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Zhipeng Hou
- South China Academy of Advanced Optoelectronics , South China Normal University , Guangzhou 510006 , China
| | - Enke Liu
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
| | - Xuekui Xi
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
| | - Feng Xu
- School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Yuan Yao
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
| | - Wenhong Wang
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
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22
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Abstract
We present a comprehensive study on anisotropic magnetocaloric porperties of the van der Waals weak-itinerant ferromagnet Fe3−xGeTe2 that features gate-tunable room-temperature ferromagnetism in few-layer device. Intrinsic magnetocrystalline anisotropy is observed to be temperature-dependent and most likely favors the long-range magnetic order in thin Fe3−xGeTe2 crsytal. The magnetic entropy change ΔSM also reveals an anisotropic characteristic between H//ab and H//c, which could be well scaled into a universal curve. The peak value \documentclass[12pt]{minimal}
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\begin{document}$$-\Delta {S}_{M}^{{\max }}$$\end{document}−ΔSMmax of 1.20 J kg−1 K−1 and the corresponding adiabatic temperature change ΔTad of 0.66 K are deduced from heat capacity with out-of-plane field change of 5 T. By fitting of the field-dependent parameters of \documentclass[12pt]{minimal}
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\begin{document}$$-\Delta {S}_{M}^{{\max }}$$\end{document}−ΔSMmax and the relative cooling power RCP, it gives \documentclass[12pt]{minimal}
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\begin{document}$$-{\rm{\triangle }}{S}_{M}^{{\max }}$$\end{document}−∆SMmax ∝ Hn with n = 0.603(6) and RCP ∝ Hm with m = 1.20(1) when H//c. Given the high and tunable Tc, Fe3−xGeTe2 crystals are of interest for fabricating the heterostructure-based spintronics device.
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Alghamdi M, Lohmann M, Li J, Jothi PR, Shao Q, Aldosary M, Su T, Fokwa BPT, Shi J. Highly Efficient Spin-Orbit Torque and Switching of Layered Ferromagnet Fe 3GeTe 2. NANO LETTERS 2019; 19:4400-4405. [PMID: 31177784 DOI: 10.1021/acs.nanolett.9b01043] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Among van der Waals (vdW) layered ferromagnets, Fe3GeTe2 (FGT) is an excellent candidate material to form FGT/heavy metal heterostructures for studying the effect of spin-orbit torques (SOT). Its metallicity, strong perpendicular magnetic anisotropy built in the single atomic layers, relatively high Curie temperature (Tc ∼ 225 K), and electrostatic gate tunability offer a tantalizing possibility of achieving the ultimate high SOT limit in monolayer all-vdW nanodevices. In this study, we fabricate heterostructures of FGT/Pt with 5 nm of Pt sputtered onto the atomically flat surface of ∼15-23 nm exfoliated FGT flakes. The spin current generated in Pt exerts a damping-like SOT on FGT magnetization. At ∼2.5 × 1011 A/m2 current density, SOT causes the FGT magnetization to switch, which is detected by the anomalous Hall effect of FGT. To quantify the SOT effect, we measure the second harmonic Hall responses as the applied magnetic field rotates the FGT magnetization in the plane. Our analysis shows that the SOT efficiency is comparable with that of the best heterostructures containing three-dimensional (3D) ferromagnetic metals and much larger than that of heterostructures containing 3D ferrimagnetic insulators. Such large efficiency is attributed to the atomically flat FGT/Pt interface, which demonstrates the great potential of exploiting vdW heterostructures for highly efficient spintronic nanodevices.
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Affiliation(s)
- Mohammed Alghamdi
- Department of Physics and Astronomy , University of California , Riverside , California 92521 , United States
| | - Mark Lohmann
- Department of Physics and Astronomy , University of California , Riverside , California 92521 , United States
| | - Junxue Li
- Department of Physics and Astronomy , University of California , Riverside , California 92521 , United States
| | - Palani R Jothi
- Department of Chemistry , University of California , Riverside , California 92521 , United States
| | - Qiming Shao
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Mohammed Aldosary
- Department of Physics and Astronomy , University of California , Riverside , California 92521 , United States
| | - Tang Su
- Department of Physics and Astronomy , University of California , Riverside , California 92521 , United States
- International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , P.R. China
| | - Boniface P T Fokwa
- Department of Chemistry , University of California , Riverside , California 92521 , United States
| | - Jing Shi
- Department of Physics and Astronomy , University of California , Riverside , California 92521 , United States
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Li H, Ruan S, Zeng YJ. Intrinsic Van Der Waals Magnetic Materials from Bulk to the 2D Limit: New Frontiers of Spintronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1900065. [PMID: 31069896 DOI: 10.1002/adma.201900065] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 02/21/2019] [Indexed: 05/22/2023]
Abstract
2D van der Waals (vdW) magnets, which present intrinsic ferromagnetic/antiferromagnetic ground states at finite temperatures down to atomic-layer thicknesses, open a new horizon in materials science and enable the potential development of new spin-related applications. The layered structure of vdW magnets facilitates their atomic-layer cleavability and magnetic anisotropy, which counteracts spin fluctuations, thereby providing an ideal platform for theoretically and experimentally exploring magnetic phase transitions in the 2D limit. With reduced dimensions, the susceptibility of 2D magnets to a large variety of external stimuli also makes them more promising than their bulk counterpart in various device applications. Here, the current status of characterization and tuning of the magnetic properties of 2D vdW magnets, particularly the atomic-layer thickness, is presented. Various state-of-the-art optical and electrical techniques have been applied to reveal the magnetic states of 2D vdW magnets. Other emerging 2D vdW magnets and future perspectives on the stacking strategy are also given; it is believed that they will excite more intensive research and provide unprecedented opportunities in the field of spintronics.
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Affiliation(s)
- Hui Li
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
- Center for Advanced Material Diagnostic Technology, Shenzhen Technology University, Shenzhen, 518118, P. R. China
| | - Shuangchen Ruan
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Yu-Jia Zeng
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
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Kim D, Park S, Lee J, Yoon J, Joo S, Kim T, Min KJ, Park SY, Kim C, Moon KW, Lee C, Hong J, Hwang C. Antiferromagnetic coupling of van der Waals ferromagnetic Fe 3GeTe 2. NANOTECHNOLOGY 2019; 30:245701. [PMID: 30802888 DOI: 10.1088/1361-6528/ab0a37] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Among two-dimensional (2D) layered van der Waals materials, ferromagnetic 2D materials can be useful for compact low-power spintronic applications. One promising candidate material is Fe3GeTe2 (FGT), which has a strong perpendicular magnetic anisotropy and relatively high Curie temperature. In this study, we confirmed that an oxide layer (O-FGT) naturally forms on top of exfoliated FGT and that an antiferromagnetic coupling (AFC) exists between FGT and O-FGT layers. From a first-principles calculation, oxide formation at the interface of each layer induces an AFC between the layers. An AFC causes a tailed hysteresis loop, where two-magnetization reversal curves are included, and a negative remanence magnetization at a certain temperature range.
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Affiliation(s)
- Dongseuk Kim
- Quantum Technology Institute, Korea Research Institute of Standards and Science, Daejeon 34113, Republic of Korea
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May AF, Ovchinnikov D, Zheng Q, Hermann R, Calder S, Huang B, Fei Z, Liu Y, Xu X, McGuire MA. Ferromagnetism Near Room Temperature in the Cleavable van der Waals Crystal Fe 5GeTe 2. ACS NANO 2019; 13:4436-4442. [PMID: 30865426 DOI: 10.1021/acsnano.8b09660] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Two-dimensional materials with intrinsic functionality are becoming increasingly important in exploring fundamental condensed matter science and for developing advanced technologies. Bulk crystals that can be exfoliated are particularly relevant to these pursuits as they provide the opportunity to study the role of physical dimensionality and explore device physics in highly crystalline samples and designer heterostructures in a routine manner. Magnetism is a key element in these endeavors; however, relatively few cleavable materials are magnetic and none possess magnetic order at ambient conditions. Here, we introduce Fe5- xGeTe2 as a cleavable material with ferromagnetic behavior at room temperature. We established intrinsic magnetic order at room temperature in bulk crystals ([Formula: see text] = 310 K) through magnetization measurements and in exfoliated, thin flakes ([Formula: see text] ≈ 280 K) using the anomalous Hall effect. Our work reveals Fe5GeTe2 as a prime candidate for incorporating intrinsic magnetism into functional van der Waals heterostructures and devices near room temperature.
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Affiliation(s)
- Andrew F May
- Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Dmitry Ovchinnikov
- Department of Physics , University of Washington , Seattle , Washington 98195 , United States
| | - Qiang Zheng
- Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Raphael Hermann
- Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Stuart Calder
- Neutron Scattering Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Bevin Huang
- Department of Physics , University of Washington , Seattle , Washington 98195 , United States
| | - Zaiyao Fei
- Department of Physics , University of Washington , Seattle , Washington 98195 , United States
| | - Yaohua Liu
- Neutron Scattering Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Xiaodong Xu
- Department of Physics , University of Washington , Seattle , Washington 98195 , United States
- Department of Materials Science and Engineering , University of Washington , Seattle , Washington 98195 , United States
| | - Michael A McGuire
- Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
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Likhanov MS, Verchenko VY, Kuznetsov AN, Shevelkov AV. ReGa 0.4Ge 0.6: Intermetallic Compound with Pronounced Covalency in the Bonding Pattern. Inorg Chem 2019; 58:2822-2832. [PMID: 30720267 DOI: 10.1021/acs.inorgchem.8b03468] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report synthesis, crystal and electronic structure, and transport properties of new intermetallic compound ReGa0.4Ge0.6, which was obtained by two-step ampule method from the elements. ReGa0.4Ge0.6 crystallizes in its own structure type (space group I4/ mmm, a = 2.89222(3) Å, c = 15.1663(3) Å, and Z = 4) which can be described as a sequential alternation of blocks of rhenium atoms and blocks of gallium and germanium atoms. Chemical bonding analysis reveals pronounced covalency of Re-Re, Re-E, and E-E (E = Ga and Ge) interactions and an interesting bonding pattern that includes many variations of localized bonding within a single compound, including pairwise homo- and heterometallic bonding, three-centered homometallic and four-centered bonding, and possibly even more delocalized bonding, which is not often encountered in such a simple intermetallic compound. Metallic behavior is confirmed by electronic structure calculations and by measurements of electrical resistivity.
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Affiliation(s)
- Maxim S Likhanov
- Department of Chemistry , Lomonosov Moscow State University , Moscow 119991 , Russia
| | - Valeriy Yu Verchenko
- Department of Chemistry , Lomonosov Moscow State University , Moscow 119991 , Russia.,National Institute for Chemical Physics and Biophysics , Tallinn 12618 , Estonia
| | - Alexey N Kuznetsov
- Department of Chemistry , Lomonosov Moscow State University , Moscow 119991 , Russia.,N. S. Kurnakov Institute of General and Inorganic Chemistry, RAS , Moscow 119991 , Russia
| | - Andrei V Shevelkov
- Department of Chemistry , Lomonosov Moscow State University , Moscow 119991 , Russia
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When two is enough: On the origin of diverse crystal structures and physical properties in the Fe-Ge system. J SOLID STATE CHEM 2019. [DOI: 10.1016/j.jssc.2018.10.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Liu J, Wang A, Pu K, Zhang S, Yang J, Musho T, Chen L. The effect of Fe vacancies and Cu adhesion on the magnetic properties of Fe3GeTe2. Phys Chem Chem Phys 2019; 21:7588-7593. [PMID: 30900706 DOI: 10.1039/c9cp00151d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The magnetic moment of FeI ions decreases significantly due to the presence of the FeII vacancies.
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Affiliation(s)
- Jia Liu
- Quzhou University
- Quzhou 324000
- P. R. China
| | | | - Kaisong Pu
- Quzhou University
- Quzhou 324000
- P. R. China
| | | | - Jianhui Yang
- Quzhou University
- Quzhou 324000
- P. R. China
- Ningbo Institute of Materials Technology and Engineering
- Chinese Academy of Sciences
| | - Terence Musho
- Department of Mechanical and Aerospace Engineering
- West Virginia University
- USA
| | - Liang Chen
- Ningbo Institute of Materials Technology and Engineering
- Chinese Academy of Sciences
- Zhejiang
- P. R. China
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Stahl J, Shlaen E, Johrendt D. The van der Waals Ferromagnets Fe5-δGeTe2and Fe5-δ-xNixGeTe2- Crystal Structure, Stacking Faults, and Magnetic Properties. Z Anorg Allg Chem 2018. [DOI: 10.1002/zaac.201800456] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Juliane Stahl
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstr. 5-13 (D) 81377 München Germany
| | - Evgeniya Shlaen
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstr. 5-13 (D) 81377 München Germany
| | - Dirk Johrendt
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstr. 5-13 (D) 81377 München Germany
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Deng Y, Yu Y, Song Y, Zhang J, Wang NZ, Sun Z, Yi Y, Wu YZ, Wu S, Zhu J, Wang J, Chen XH, Zhang Y. Gate-tunable room-temperature ferromagnetism in two-dimensional Fe3GeTe2. Nature 2018; 563:94-99. [DOI: 10.1038/s41586-018-0626-9] [Citation(s) in RCA: 1076] [Impact Index Per Article: 179.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 08/07/2018] [Indexed: 11/09/2022]
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Mao Q, Chen B, Yang J, Zhang Y, Wang H, Fang M. Critical properties of the quasi-two-dimensional metallic ferromagnet Fe 2.85GeTe 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:345802. [PMID: 30020086 DOI: 10.1088/1361-648x/aad43b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We have investigated the critical behavior of Fe2.85GeTe2 single crystals near the paramagnetic-ferromagnetic transition by bulk dc magnetization measurements. The critical exponents β, γ and δ, obtained from modified Arrott plot, Kouvel-Fisher method, and critical isothermal magnetization analysis, could fulfill the Widom scaling law. The self-consistency and reliability of these exponents are further verified by the magnetic state equations below and above the Curie temperature at high magnetic field. In addition, the exchange distance deduced from the susceptibility exponent is shown to decay as [Formula: see text]. Based on the observations, we suggest that the competition between direct magnetic exchange and Coulombic and/or RKKY interactions should be responsible for the intrinsic magnetism in this system.
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Affiliation(s)
- Qianhui Mao
- College of Science, Henan University of Engineering, Xinzheng 451191, People's Republic of China. Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
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Zhang Y, Lu H, Zhu X, Tan S, Feng W, Liu Q, Zhang W, Chen Q, Liu Y, Luo X, Xie D, Luo L, Zhang Z, Lai X. Emergence of Kondo lattice behavior in a van der Waals itinerant ferromagnet, Fe 3GeTe 2. SCIENCE ADVANCES 2018; 4:eaao6791. [PMID: 29349301 PMCID: PMC5770166 DOI: 10.1126/sciadv.aao6791] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/29/2017] [Indexed: 05/28/2023]
Abstract
Searching for heavy fermion (HF) states in non-f-electron systems becomes an interesting issue, especially in the presence of magnetism, and can help explain the physics of complex compounds. Using angle-resolved photoemission spectroscopy, scanning tunneling microscopy, physical properties measurements, and the first-principles calculations, we observe the HF state in a 3d-electron van der Waals ferromagnet, Fe3GeTe2. Upon entering the ferromagnetic state, a massive spectral weight transfer occurs, which results from the exchange splitting. Meanwhile, the Fermi surface volume and effective electron mass are both enhanced. When the temperature drops below a characteristic temperature T*, heavy electrons gradually emerge with further enhanced effective electron mass. The coexistence of ferromagnetism and HF state can be well interpreted by the dual properties (itinerant and localized) of 3d electrons. This work expands the limit of ferromagnetic HF materials from f- to d-electron systems and illustrates the positive correlation between ferromagnetism and HF state in the 3d-electron material, which is quite different from the f-electron systems.
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Affiliation(s)
- Yun Zhang
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - Haiyan Lu
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Xiegang Zhu
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Shiyong Tan
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Wei Feng
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Qin Liu
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Wen Zhang
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Qiuyun Chen
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Yi Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
| | - Xuebing Luo
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Donghua Xie
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Lizhu Luo
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Zhengjun Zhang
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Xinchun Lai
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
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Critical behavior of the van der Waals bonded high T C ferromagnet Fe 3GeTe 2. Sci Rep 2017; 7:6184. [PMID: 28733606 PMCID: PMC5522457 DOI: 10.1038/s41598-017-06671-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 06/14/2017] [Indexed: 11/08/2022] Open
Abstract
Fe3GeTe2 is a promising candidate for van der Waals bonded ferromagnet because of its high Curie temperature and the prediction that its ferromagnetism can maintain upon exfoliating down to single layer. Here, we have reported the critical behavior to understand its ferromagnetic exchange. Based on various techniques including modified Arrott plot, Kouvel-Fisher plot, and critical isotherm analysis, a set of reliable critical exponents (β = 0.327 ± 0.003, γ = 1.079 ± 0.005, and δ = 4.261 ± 0.009) has been obtained. The critical behavior suggests a three-dimensional long-range magnetic coupling with the exchange distance decaying as J(r) ≈ r−4.6 in Fe3GeTe2. The possible origin of three-dimensional magnetic characteristics in van der Waals bonded magnets is discussed.
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Kuznetsov AN, Stroganova EA, Zakharova EY, Solopchenko AV, Sobolev AV, Presniakov IA, Kirdyankin DI, Novotortsev VM. Mixed nickel-gallium tellurides Ni 3−x GaTe 2 as a matrix for incorporating magnetic cations: A Ni 3−x Fe x GaTe 2 series. J SOLID STATE CHEM 2017. [DOI: 10.1016/j.jssc.2017.03.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Khalaniya RA, Mironov AV, Verchenko VY, Jesche A, Tsirlin AA, Shevelkov AV. Nontrivial Recurrent Intergrowth Structure and Unusual Magnetic Behavior of Intermetallic Compound Fe 32+δGe 33As 2. Inorg Chem 2016; 55:12953-12961. [PMID: 27989149 DOI: 10.1021/acs.inorgchem.6b02412] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new phase Fe32+δGe33As2 (δ ≤ 0.136) was obtained by two-step synthesis from the elements. Fe32+δGe33As2 crystallizes in its own structure type (space group P6/mmm, Z = 1, a = 11.919(3) Å, c = 7.558(4) Å) that can be described as a recurrent two-dimensional intergrowth of two intermetallic structure types, MgFe6Ge6 and Co2Al5. Their blocks are represented by infinite columns in the structure. No visible structural changes were observed in the temperature range from 10 to 300 K. At 125 K, Fe32+δGe33As2 undergoes an antiferromagnetic-like transition, while above 150 K it shows a typical Curie-Weiss paramagnetic behavior. Below the transition temperature, a peculiar field-dependent magnetic susceptibility, that shows a significant increase of the susceptibility upon increasing the magnetic field, and a change in transport properties have been observed. Above 140 K, Fe32+δGe33As2 reveals a metallic behavior, in agreement with electronic structure calculation, while below this point the resistivity nonmonotonically increases upon cooling. The Seebeck coefficient is positive, indicating that holes are the major charge carriers, and shows a broad maximum around 57 K.
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Affiliation(s)
- Roman A Khalaniya
- Department of Chemistry, Lomonosov Moscow State University , 119991 Moscow, Russia
| | - Andrei V Mironov
- Department of Chemistry, Lomonosov Moscow State University , 119991 Moscow, Russia
| | - Valeriy Yu Verchenko
- Department of Chemistry, Lomonosov Moscow State University , 119991 Moscow, Russia.,National Institute of Chemical Physics and Biophysics , 12618 Tallinn, Estonia
| | - Anton Jesche
- Experimental Physics VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg , 86135 Augsburg, Germany
| | - Alexander A Tsirlin
- Experimental Physics VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg , 86135 Augsburg, Germany
| | - Andrei V Shevelkov
- Department of Chemistry, Lomonosov Moscow State University , 119991 Moscow, Russia
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Verchenko VY, Sokolov SS, Tsirlin AA, Sobolev AV, Presniakov IA, Bykov MA, Kirsanova MA, Shevelkov AV. New Fe-based layered telluride Fe 3-δAs 1-yTe 2: synthesis, crystal structure and physical properties. Dalton Trans 2016; 45:16938-16947. [PMID: 27722484 DOI: 10.1039/c6dt02721k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new ternary telluride, Fe3-δAs1-yTe2, was synthesized from elements at 600 °C. It crystallizes in the hexagonal P63/mmc space group with the unit cell parameters a = 3.85091(9) Å and c = 17.1367(4) Å for δ = 0.3 and y = 0.04. Its layered crystal structure contains partially occupied intralayer and interlayer Fe positions, which give rise to significant nonstoichiometry: Fe3-δAs1-yTe2 was found to possess the homogeneity range of 0.25 < δ < 0.45 and y = 0.04. Regions of local vacancy ordering alternate with regions of randomly distributed vacancies, so that the ordering of Fe atoms and vacancies is not complete in the average structure. Clear evidence of the magnetic phase transition is obtained by thermodynamic measurements, Mössbauer spectroscopy, and neutron powder diffraction. Magnetic susceptibility measurements reveal weak ferromagnetism below TC = 123 K with a net moment of MS∼ 0.1μB/Fe at T = 2 K. This transition is confirmed by differential scanning calorimetry. Additionally, neutron powder diffraction indicates the onset of a complex AFM-like magnetic ordering below 100 K.
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Affiliation(s)
- Valeriy Yu Verchenko
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
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Effect of Transition Metal Substitution on the Structure and Properties of a Clathrate-Like Compound Eu₇Cu 44As 23. MATERIALS 2016; 9:ma9070587. [PMID: 28773714 PMCID: PMC5456878 DOI: 10.3390/ma9070587] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 07/06/2016] [Accepted: 07/14/2016] [Indexed: 11/30/2022]
Abstract
A series of substitutional solid solutions—Eu7Cu44−xTxAs23 (T = Fe, Co, Ni)—based on a recently discovered clathrate-like compound (Eu7Cu44As23) were synthesized from the elements at 800 °C. Almost up to 50% of Cu can be substituted by Ni, resulting in a linear decrease of the cubic unit cell parameter from a = 16.6707(1) Å for the ternary compound to a = 16.3719(1) Å for the sample with the nominal composition Eu7Cu24Ni20As23. In contrast, Co and Fe can only substitute less than 20% of Cu. Crystal structures of six samples of different composition were refined from powder diffraction data. Despite very small differences in scattering powers of Cu, Ni, Co, and Fe, we were able to propose a reasonable model of dopant distribution over copper sites based on the trends in interatomic distances as well as on Mössbauer spectra for the iron-substituted compound Eu7Cu36Fe8As23. Ni doping increases the Curie temperature to 25 K with respect to the parent compound, which is ferromagnetically ordered below 17.5 K, whereas Fe doping suppresses the ferromagnetic ordering in the Eu sublattice.
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