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Shimazaki T, Tachikawa M. Theoretical study of short-range exchange interaction based on semiconductor dielectric function model toward time-dependent dielectric density functional theory. J Chem Phys 2024; 161:014107. [PMID: 38949277 DOI: 10.1063/5.0207751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Accepted: 06/12/2024] [Indexed: 07/02/2024] Open
Abstract
This study explores various models of semiconductor dielectric functions, with a specific emphasis on the large wavenumber spectrum and the derivation of the screened exchange interaction. Particularly, we discuss the short-range effect of the screened exchange potential. Our investigation reveals that the short-range effect originating from the high wavenumber spectrum is contingent upon the dielectric constant of the targeted system. To incorporate dielectric-dependent behaviors concerning the short-range aspect into the dielectric density functional theory (DFT) framework, we utilize the local Slater term and the Yukawa-type term, adjusting the ratio between these terms based on the dielectric constant. Additionally, we demonstrate the efficacy of the time-dependent dielectric DFT method in accurately characterizing the electronic structure of excited states in dyes and functional molecules. Several theoretical approaches have incorporated parameters dependent on the system to elucidate short-range exchange interactions. Our theoretical analysis and discussions will be useful for those studies.
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Affiliation(s)
- Tomomi Shimazaki
- Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-Ku, Yokohama 236-0026, Japan
| | - Masanori Tachikawa
- Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-Ku, Yokohama 236-0026, Japan
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2
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Liu P, Zhang Y, Li K, Li Y, Pu Y. Recent advances in 2D van der Waals magnets: Detection, modulation, and applications. iScience 2023; 26:107584. [PMID: 37664598 PMCID: PMC10470320 DOI: 10.1016/j.isci.2023.107584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023] Open
Abstract
The emergence of two-dimensional (2D) van der Waals magnets provides an exciting platform for exploring magnetism in the monolayer limit. Exotic quantum phenomena and significant potential for spintronic applications are demonstrated in 2D magnetic crystals and heterostructures, which offer unprecedented possibilities in advanced formation technology with low power and high efficiency. In this review, we summarize recent advances in 2D van der Waals magnetic crystals. We focus mainly on van der Waals materials of truly 2D nature with intrinsic magnetism. The detection methods of 2D magnetic materials are first introduced in detail. Subsequently, the effective strategies to modulate the magnetic behavior of 2D magnets (e.g., Curie temperature, magnetic anisotropy, magnetic exchange interaction) are presented. Then, we list the applications of 2D magnets in the spintronic devices. We also highlight current challenges and broad space for the development of 2D magnets in further studies.
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Affiliation(s)
- Ping Liu
- School of Science & New Energy Technology Engineering Laboratory of Jiangsu Province, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Ying Zhang
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei 230026, China
| | - Kehan Li
- School of Science & New Energy Technology Engineering Laboratory of Jiangsu Province, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Yongde Li
- School of Science & New Energy Technology Engineering Laboratory of Jiangsu Province, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Yong Pu
- School of Science & New Energy Technology Engineering Laboratory of Jiangsu Province, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
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Wu F, Gibertini M, Watanabe K, Taniguchi T, Gutiérrez-Lezama I, Ubrig N, Morpurgo AF. Magnetism-Induced Band-Edge Shift as the Mechanism for Magnetoconductance in CrPS 4 Transistors. NANO LETTERS 2023; 23:8140-8145. [PMID: 37610296 DOI: 10.1021/acs.nanolett.3c02274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Transistors realized on the 2D antiferromagnetic semiconductor CrPS4 exhibit large magnetoconductance due to magnetic-field-induced changes in the magnetic state. The microscopic mechanism coupling the conductance and magnetic state is not understood. We identify it by analyzing the evolution of the parameters determining the transistor behavior─carrier mobility and threshold voltage─with temperature and magnetic field. For temperatures T near the Néel temperature TN, the magnetoconductance originates from a mobility increase due to the applied magnetic field that reduces spin fluctuation induced disorder. For T ≪ TN, instead, what changes is the threshold voltage, so that increasing the field at fixed gate voltage increases the density of accumulated electrons. The phenomenon is explained by a conduction band-edge shift correctly predicted by the ab initio calculations. Our results demonstrate that the band structure of CrPS4 depends on its magnetic state and reveal a mechanism for magnetoconductance that had not been identified earlier.
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Affiliation(s)
- Fan Wu
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland
| | - Marco Gibertini
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, University of Modena and Reggio Emilia, IT-41125 Modena, Italy
- Centro S3, CNR Istituto Nanoscienze, IT-41125 Modena, Italy
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Ignacio Gutiérrez-Lezama
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland
| | - Nicolas Ubrig
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland
| | - Alberto F Morpurgo
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland
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Yao F, Multian V, Wang Z, Ubrig N, Teyssier J, Wu F, Giannini E, Gibertini M, Gutiérrez-Lezama I, Morpurgo AF. Multiple antiferromagnetic phases and magnetic anisotropy in exfoliated CrBr 3 multilayers. Nat Commun 2023; 14:4969. [PMID: 37591960 PMCID: PMC10435511 DOI: 10.1038/s41467-023-40723-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 08/08/2023] [Indexed: 08/19/2023] Open
Abstract
In twisted two-dimensional (2D) magnets, the stacking dependence of the magnetic exchange interaction can lead to regions of ferromagnetic and antiferromagnetic interlayer order, separated by non-collinear, skyrmion-like spin textures. Recent experimental searches for these textures have focused on CrI3, known to exhibit either ferromagnetic or antiferromagnetic interlayer order, depending on layer stacking. However, the very strong uniaxial anisotropy of CrI3 disfavors smooth non-collinear phases in twisted bilayers. Here, we report the experimental observation of three distinct magnetic phases-one ferromagnetic and two antiferromagnetic-in exfoliated CrBr3 multilayers, and reveal that the uniaxial anisotropy is significantly smaller than in CrI3. These results are obtained by magnetoconductance measurements on CrBr3 tunnel barriers and Raman spectroscopy, in conjunction with density functional theory calculations, which enable us to identify the stackings responsible for the different interlayer magnetic couplings. The detection of all locally stable magnetic states predicted to exist in CrBr3 and the excellent agreement found between theory and experiments, provide complete information on the stacking-dependent interlayer exchange energy and establish twisted bilayer CrBr3 as an ideal system to deterministically create non-collinear magnetic phases.
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Affiliation(s)
- Fengrui Yao
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.
| | - Volodymyr Multian
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
- Advanced Materials Nonlinear Optical Diagnostics lab, Institute of Physics, NAS of Ukraine, 46 Nauky pr., 03028, Kyiv, Ukraine
| | - Zhe Wang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Advanced Materials and Mesoscopic Physics, School of Physics, Xi'an Jiaotong University, Xi'an, 710049, China.
| | - Nicolas Ubrig
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Jérémie Teyssier
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Fan Wu
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Enrico Giannini
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Marco Gibertini
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, University of Modena and Reggio Emilia, IT-41125, Modena, Italy
- Centro S3, CNR-Istituto Nanoscienze, IT-41125, Modena, Italy
| | - Ignacio Gutiérrez-Lezama
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Alberto F Morpurgo
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.
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Tomarchio L, Mosesso L, Macis S, Nguyen LT, Grilli A, Romani M, Cestelli Guidi M, Cava RJ, Lupi S. Phonon Anharmonicity and Spin-Phonon Coupling in CrI 3. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4909. [PMID: 37512184 PMCID: PMC10381855 DOI: 10.3390/ma16144909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 07/01/2023] [Accepted: 07/06/2023] [Indexed: 07/30/2023]
Abstract
We report on the far-infrared, temperature-dependent optical properties of a CrI3 transition metal halide single crystal, a van der Waals ferromagnet (FM) with a Curie temperature of 61 K. In addition to the expected phonon modes determined by the crystalline symmetry, the optical reflectance and transmittance spectra of CrI3 single crystals show many other excitations as a function of temperature as a consequence of the combination of a strong lattice anharmonicity and spin-phonon coupling. This complex vibrational spectrum highlights the presence of entangled interactions among the different degrees of freedom in CrI3.
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Affiliation(s)
- Luca Tomarchio
- Department of Physics, Sapienza University, Piazzale Aldo Moro 5, 00185 Rome, Italy
- INFN Section of Rome, P.Le Aldo Moro, 2, 00185 Rome, Italy
| | - Lorenzo Mosesso
- Department of Physics, Sapienza University, Piazzale Aldo Moro 5, 00185 Rome, Italy
- INFN Section of Rome, P.Le Aldo Moro, 2, 00185 Rome, Italy
| | - Salvatore Macis
- Department of Physics, Sapienza University, Piazzale Aldo Moro 5, 00185 Rome, Italy
- INFN-Laboratori Nazionali di Frascati, Via Enrico Fermi 54, 00044 Rome, Italy
| | - Loi T Nguyen
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Antonio Grilli
- INFN-Laboratori Nazionali di Frascati, Via Enrico Fermi 54, 00044 Rome, Italy
| | - Martina Romani
- INFN-Laboratori Nazionali di Frascati, Via Enrico Fermi 54, 00044 Rome, Italy
| | | | - Robert J Cava
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Stefano Lupi
- Department of Physics, Sapienza University, Piazzale Aldo Moro 5, 00185 Rome, Italy
- INFN Section of Rome, P.Le Aldo Moro, 2, 00185 Rome, Italy
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Grzeszczyk M, Acharya S, Pashov D, Chen Z, Vaklinova K, van Schilfgaarde M, Watanabe K, Taniguchi T, Novoselov KS, Katsnelson MI, Koperski M. Strongly Correlated Exciton-Magnetization System for Optical Spin Pumping in CrBr 3 and CrI 3 . ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209513. [PMID: 36787625 DOI: 10.1002/adma.202209513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 01/13/2023] [Indexed: 05/17/2023]
Abstract
Ferromagnetism in van der Waals systems, preserved down to a monolayer limit, attracted attention to a class of materials with general composition CrX3 (X=I, Br, and Cl), which are treated now as canonical 2D ferromagnets. Their diverse magnetic properties, such as different easy axes or varying and controllable character of in-plane or interlayer ferromagnetic coupling, make them promising candidates for spintronic, photonic, optoelectronic, and other applications. Still, significantly different magneto-optical properties between the three materials have been presenting a challenging puzzle for researchers over the last few years. Herewith, it is demonstrated that despite similar structural and magnetic configurations, the coupling between excitons and magnetization is qualitatively different in CrBr3 and CrI3 films. Through a combination of the optical spin pumping experiments with the state-of-the-art theory describing bound excitonic states in the presence of magnetization, we concluded that the hole-magnetization coupling has the opposite sign in CrBr3 and CrI3 and also between the ground and excited exciton state. Consequently, efficient spin pumping capabilities are demonstrated in CrBr3 driven by magnetization via spin-dependent absorption, and the different origins of the magnetic hysteresis in CrBr3 and CrI3 are unraveled.
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Affiliation(s)
- M Grzeszczyk
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
| | - S Acharya
- Institute for Molecules and Materials, Radboud University, AJ Nijmegen, NL-6525, The Netherlands
- National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - D Pashov
- King's College London, Theory and Simulation of Condensed Matter, The Strand, London, WC2R 2LS, UK
| | - Z Chen
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
| | - K Vaklinova
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
| | - M van Schilfgaarde
- National Renewable Energy Laboratory, Golden, CO, 80401, USA
- King's College London, Theory and Simulation of Condensed Matter, The Strand, London, WC2R 2LS, UK
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, 305-0044, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, 305-0044, Japan
| | - K S Novoselov
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - M I Katsnelson
- Institute for Molecules and Materials, Radboud University, AJ Nijmegen, NL-6525, The Netherlands
| | - M Koperski
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
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7
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Basak K, Ghosh M, Chowdhury S, Jana D. Theoretical studies on electronic, magnetic and optical properties of two dimensional transition metal trihalides. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:233001. [PMID: 36854185 DOI: 10.1088/1361-648x/acbffb] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
Two dimensional transition metal trihalides have drawn attention over the years due to their intrinsic ferromagnetism and associated large anisotropy at nanoscale. The interactions involved in these layered structures are of van der Waals types which are important for exfoliation to different thin samples. This enables one to compare the journey of physical properties from bulk structures to monolayer counterpart. In this topical review, the modulation of electronic, magnetic and optical properties by strain engineering, alloying, doping, defect engineering etc have been discussed extensively. The results obtained by first principle density functional theory calculations are verified by recent experimental observations. The relevant experimental synthesis of different morphological transition metal trihalides are highlighted. The feasibility of such routes may indicate other possible heterostructures. Apart from spintronics based applications, transition metal trihalides are potential candidates in sensing and data storage. Moreover, high thermoelectric figure of merit of chromium trihalides at higher temperatures leads to the possibility of multi-purpose applications. We hope this review will give important directions to further research in transition metal trihalide systems having tunable band gap with reduced dimensionalities.
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Affiliation(s)
- Krishnanshu Basak
- Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Mainak Ghosh
- Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Suman Chowdhury
- S.N. Bose National Centre for Basic Sciences, JD-III Salt Lake City, Kolkata 700098, India
- Department of Physics, Shiv Nadar University, Greater Noida, Uttar Pradesh 201314, India
| | - Debnarayan Jana
- Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009, India
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Li X, Wang A, Chen H, Tao W, Chen Z, Zhang C, Li Y, Zhang Y, Shang H, Weng YX, Zhao J, Zhu H. Ultrafast Spontaneous Localization of a Jahn-Teller Exciton Polaron in Two-Dimensional Semiconducting CrI 3 by Symmetry Breaking. NANO LETTERS 2022; 22:8755-8762. [PMID: 36305523 DOI: 10.1021/acs.nanolett.2c03689] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The excited state species and properties in low-dimensional semiconductors can be completely redefined by electron-lattice coupling or a polaronic effect. Here, by combining ultrafast broadband pump-probe spectroscopy and first-principles GW and Bethe-Salpeter equation calculations, we show semiconducting CrI3 as a prototypical 2D polaronic system with characteristic Jahn-Teller exciton polaron induced by symmetry breaking. A photogenerated electron and hole in CrI3 localize spontaneously in ∼0.9 ps and pair geminately to a Jahn-Teller exciton polaron with elongated Cr-I octahedra, large binding energy, and an unprecedentedly small exciton-exciton annihilation rate constant (∼10-20 cm3 s-1). Coherent phonon dynamics indicates the localization is mainly triggered by the coherent nuclear vibration of the I-Cr-I out-of-plane stretch mode at 128.5 ± 0.1 cm-1. The excited state Jahn-Teller exciton polaron in CrI3 broadens the realm of 2D polaron systems and reveals the decisive role of coupled electron-lattice motion on excited state properties and exciton physics in 2D semiconductors.
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Affiliation(s)
- Xufeng Li
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang310027, China
| | - Aolei Wang
- Department of Physics, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and ICQD/Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui230026, China
| | - Hailong Chen
- Beijing National Laboratory for Condensed Matter Physics, The Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
| | - Weijian Tao
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang310027, China
| | - Zeng Chen
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang310027, China
| | - Chi Zhang
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang310027, China
| | - Yujie Li
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang310027, China
| | - Yiran Zhang
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang310027, China
| | - Honghui Shang
- Department of Physics, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and ICQD/Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui230026, China
| | - Yu-Xiang Weng
- Beijing National Laboratory for Condensed Matter Physics, The Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
| | - Jin Zhao
- Department of Physics, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and ICQD/Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui230026, China
| | - Haiming Zhu
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang310027, China
- ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, Zhejiang311200, China
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Nikitin SE, Fåk B, Krämer KW, Fennell T, Normand B, Läuchli AM, Rüegg C. Thermal Evolution of Dirac Magnons in the Honeycomb Ferromagnet CrBr_{3}. PHYSICAL REVIEW LETTERS 2022; 129:127201. [PMID: 36179160 DOI: 10.1103/physrevlett.129.127201] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 08/17/2022] [Indexed: 06/16/2023]
Abstract
CrBr_{3} is an excellent realization of the two-dimensional honeycomb ferromagnet, which offers a bosonic equivalent of graphene with Dirac magnons and topological character. We perform inelastic neutron scattering measurements using state-of-the-art instrumentation to update 50-year-old data, thereby enabling a definitive comparison both with recent experimental claims of a significant gap at the Dirac point and with theoretical predictions for thermal magnon renormalization. We demonstrate that CrBr_{3} has next-neighbor J_{2} and J_{3} interactions approximately 5% of J_{1}, an ideal Dirac magnon dispersion at the K point, and the associated signature of isospin winding. The magnon lifetime and the thermal band renormalization show the universal T^{2} evolution expected from an interacting spin-wave treatment, but the measured dispersion lacks the predicted van Hove features, pointing to the need for more sophisticated theoretical analysis.
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Affiliation(s)
- S E Nikitin
- Quantum Criticality and Dynamics Group, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
| | - B Fåk
- Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, F-38042 Grenoble Cedex 9, France
| | - K W Krämer
- Department of Chemistry, Biochemistry and Pharmacy, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - T Fennell
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - B Normand
- Laboratory for Theoretical and Computational Physics, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - A M Läuchli
- Laboratory for Theoretical and Computational Physics, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Ch Rüegg
- Quantum Criticality and Dynamics Group, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute for Quantum Electronics, ETH Zürich, CH-8093 Hönggerberg, Switzerland
- Department of Quantum Matter Physics, University of Geneva, CH-1211 Geneva, Switzerland
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10
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Shimazaki T, Tachikawa M. Theoretical study of the effect of nonlocal short-range exchange on calculations of molecular excitation energies in the dielectric screened-exchange method. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Tenasini G, Soler-Delgado D, Wang Z, Yao F, Dumcenco D, Giannini E, Watanabe K, Taniguchi T, Moulsdale C, Garcia-Ruiz A, Fal'ko VI, Gutiérrez-Lezama I, Morpurgo AF. Band Gap Opening in Bilayer Graphene-CrCl 3/CrBr 3/CrI 3 van der Waals Interfaces. NANO LETTERS 2022; 22:6760-6766. [PMID: 35930625 DOI: 10.1021/acs.nanolett.2c02369] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We report experimental investigations of transport through bilayer graphene (BLG)/chromium trihalide (CrX3; X = Cl, Br, I) van der Waals interfaces. In all cases, a large charge transfer from BLG to CrX3 takes place (reaching densities in excess of 1013 cm-2), and generates an electric field perpendicular to the interface that opens a band gap in BLG. We determine the gap from the activation energy of the conductivity and find excellent agreement with the latest theory accounting for the contribution of the σ bands to the BLG dielectric susceptibility. We further show that for BLG/CrCl3 and BLG/CrBr3 the band gap can be extracted from the gate voltage dependence of the low-temperature conductivity, and use this finding to refine the gap dependence on the magnetic field. Our results allow a quantitative comparison of the electronic properties of BLG with theoretical predictions and indicate that electrons occupying the CrX3 conduction band are correlated.
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Affiliation(s)
| | | | - Zhe Wang
- MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Advanced Materials and Mesoscopic Physics, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | | | | | | | - Kenji Watanabe
- Research Center for Functional Materials, NIMS, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, NIMS, 1-1 Namiki, Tsukuba 305-0044, Japan
| | | | | | - Vladimir I Fal'ko
- Henry Royce Institute for Advanced Materials, Manchester M13 9PL, U.K
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12
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Wang G, Kincaid B, Zhou H, Annaberdiyev A, Bennett MC, Krogel JT, Mitas L. A new generation of effective core potentials from correlated and spin-orbit calculations: selected heavy elements. J Chem Phys 2022; 157:054101. [DOI: 10.1063/5.0087300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We introduce new correlation consistent effective core potentials (ccECPs) for the elements I, Te, Bi, Ag, Au, Pd, Ir, Mo, and W with $4d$, $5d$, $6s$ and $6p$ valence spaces. These ccECPs are given as a sum of spin-orbit averaged relativistic effective potential (AREP) and effective spin-orbit (SO) terms. The construction involves several steps with increasing refinements from more simple to fully correlated methods. The optimizations are carried out with objective functions that include weighted many-body atomic spectra, norm-conservation criteria, and spin-orbit splittings. Transferability tests involve molecular binding curves of corresponding hydride and oxide dimers. The constructed ccECPs are systematically better and in a few cases on par with previous effective core potential (ECP) tables on all tested criteria and provide a significant increase in accuracy for valence-only calculations with these elements. Our study confirms the importance of the AREP part in determining the overall quality of the ECP even in the presence of sizable spin-orbit effects. The subsequent quantum Monte Carlo (QMC) calculations point out the importance of accurate trial wave functions which in some cases (mid series transition elements) require treatment well beyond single-reference.
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Affiliation(s)
| | | | - Haihan Zhou
- NC State University, United States of America
| | | | | | - Jaron T. Krogel
- Materials Science and Technology Division, Oak Ridge National Laboratory, United States of America
| | - Lubos Mitas
- North Carolina State University, United States of America
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13
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Wang QH, Bedoya-Pinto A, Blei M, Dismukes AH, Hamo A, Jenkins S, Koperski M, Liu Y, Sun QC, Telford EJ, Kim HH, Augustin M, Vool U, Yin JX, Li LH, Falin A, Dean CR, Casanova F, Evans RFL, Chshiev M, Mishchenko A, Petrovic C, He R, Zhao L, Tsen AW, Gerardot BD, Brotons-Gisbert M, Guguchia Z, Roy X, Tongay S, Wang Z, Hasan MZ, Wrachtrup J, Yacoby A, Fert A, Parkin S, Novoselov KS, Dai P, Balicas L, Santos EJG. The Magnetic Genome of Two-Dimensional van der Waals Materials. ACS NANO 2022; 16:6960-7079. [PMID: 35442017 PMCID: PMC9134533 DOI: 10.1021/acsnano.1c09150] [Citation(s) in RCA: 68] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 02/23/2022] [Indexed: 05/23/2023]
Abstract
Magnetism in two-dimensional (2D) van der Waals (vdW) materials has recently emerged as one of the most promising areas in condensed matter research, with many exciting emerging properties and significant potential for applications ranging from topological magnonics to low-power spintronics, quantum computing, and optical communications. In the brief time after their discovery, 2D magnets have blossomed into a rich area for investigation, where fundamental concepts in magnetism are challenged by the behavior of spins that can develop at the single layer limit. However, much effort is still needed in multiple fronts before 2D magnets can be routinely used for practical implementations. In this comprehensive review, prominent authors with expertise in complementary fields of 2D magnetism (i.e., synthesis, device engineering, magneto-optics, imaging, transport, mechanics, spin excitations, and theory and simulations) have joined together to provide a genome of current knowledge and a guideline for future developments in 2D magnetic materials research.
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Affiliation(s)
- Qing Hua Wang
- Materials
Science and Engineering, School for Engineering of Matter, Transport
and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Amilcar Bedoya-Pinto
- NISE
Department, Max Planck Institute of Microstructure
Physics, 06120 Halle, Germany
- Instituto
de Ciencia Molecular (ICMol), Universitat
de València, 46980 Paterna, Spain
| | - Mark Blei
- Materials
Science and Engineering, School for Engineering of Matter, Transport
and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Avalon H. Dismukes
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Assaf Hamo
- Department
of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Sarah Jenkins
- Twist
Group,
Faculty of Physics, University of Duisburg-Essen, Campus Duisburg, 47057 Duisburg, Germany
| | - Maciej Koperski
- Institute
for Functional Intelligent Materials, National
University of Singapore, 117544 Singapore
| | - Yu Liu
- Condensed
Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Qi-Chao Sun
- Physikalisches
Institut, University of Stuttgart, 70569 Stuttgart, Germany
| | - Evan J. Telford
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
- Department
of Physics, Columbia University, New York, New York 10027, United States
| | - Hyun Ho Kim
- School
of Materials Science and Engineering, Department of Energy Engineering
Convergence, Kumoh National Institute of
Technology, Gumi 39177, Korea
| | - Mathias Augustin
- Institute
for Condensed Matter Physics and Complex Systems, School of Physics
and Astronomy, The University of Edinburgh, Edinburgh, EH9 3FD, United Kingdom
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain
| | - Uri Vool
- Department
of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- John Harvard
Distinguished Science Fellows Program, Harvard
University, Cambridge, Massachusetts 02138, United States
| | - Jia-Xin Yin
- Laboratory
for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, New Jersey 08544, United States
| | - Lu Hua Li
- Institute
for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Waurn Ponds, Victoria 3216, Australia
| | - Alexey Falin
- Institute
for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Waurn Ponds, Victoria 3216, Australia
| | - Cory R. Dean
- Department
of Physics, Columbia University, New York, New York 10027, United States
| | - Fèlix Casanova
- CIC nanoGUNE
BRTA, 20018 Donostia - San Sebastián, Basque
Country, Spain
- IKERBASQUE,
Basque Foundation for Science, 48013 Bilbao, Basque Country, Spain
| | - Richard F. L. Evans
- Department
of Physics, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Mairbek Chshiev
- Université
Grenoble Alpes, CEA, CNRS, Spintec, 38000 Grenoble, France
- Institut
Universitaire de France, 75231 Paris, France
| | - Artem Mishchenko
- Department
of Physics and Astronomy, University of
Manchester, Manchester, M13 9PL, United Kingdom
- National
Graphene Institute, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Cedomir Petrovic
- Condensed
Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Rui He
- Department
of Electrical and Computer Engineering, Texas Tech University, 910 Boston Avenue, Lubbock, Texas 79409, United
States
| | - Liuyan Zhao
- Department
of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109, United States
| | - Adam W. Tsen
- Institute
for Quantum Computing and Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Brian D. Gerardot
- SUPA, Institute
of Photonics and Quantum Sciences, Heriot-Watt
University, Edinburgh EH14 4AS, United Kingdom
| | - Mauro Brotons-Gisbert
- SUPA, Institute
of Photonics and Quantum Sciences, Heriot-Watt
University, Edinburgh EH14 4AS, United Kingdom
| | - Zurab Guguchia
- Laboratory
for Muon Spin Spectroscopy, Paul Scherrer
Institute, CH-5232 Villigen PSI, Switzerland
| | - Xavier Roy
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Sefaattin Tongay
- Materials
Science and Engineering, School for Engineering of Matter, Transport
and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Ziwei Wang
- Department
of Physics and Astronomy, University of
Manchester, Manchester, M13 9PL, United Kingdom
- National
Graphene Institute, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - M. Zahid Hasan
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Princeton
Institute for Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Joerg Wrachtrup
- Physikalisches
Institut, University of Stuttgart, 70569 Stuttgart, Germany
- Max Planck
Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Amir Yacoby
- Department
of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- John A.
Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Albert Fert
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain
- Unité
Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767 Palaiseau, France
- Department
of Materials Physics UPV/EHU, 20018 Donostia - San Sebastián, Basque Country, Spain
| | - Stuart Parkin
- NISE
Department, Max Planck Institute of Microstructure
Physics, 06120 Halle, Germany
| | - Kostya S. Novoselov
- Institute
for Functional Intelligent Materials, National
University of Singapore, 117544 Singapore
| | - Pengcheng Dai
- Department
of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
| | - Luis Balicas
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
- Department
of Physics, Florida State University, Tallahassee, Florida 32306, United States
| | - Elton J. G. Santos
- Institute
for Condensed Matter Physics and Complex Systems, School of Physics
and Astronomy, The University of Edinburgh, Edinburgh, EH9 3FD, United Kingdom
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain
- Higgs Centre
for Theoretical Physics, The University
of Edinburgh, Edinburgh EH9 3FD, United Kingdom
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14
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Degradation Effect and Magnetoelectric Transport Properties in CrBr 3 Devices. MATERIALS 2022; 15:ma15093007. [PMID: 35591342 PMCID: PMC9104061 DOI: 10.3390/ma15093007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 04/14/2022] [Accepted: 04/19/2022] [Indexed: 02/04/2023]
Abstract
Two-dimensional (2D) magnetic materials exhibiting unique 2D-limit magnetism have attracted great attention due to their potential applications in ultrathin spintronic devices. These 2D magnetic materials and their heterostructures provide a unique platform for exploring physical effect and exotic phenomena. However, the degradation of most 2D magnetic materials at ambient conditions has so far hindered their characterization and integration into ultrathin devices. Furthermore, the effect of degradation on magnetoelectric transport properties, which is measured for the demonstration of exotic phenomena and device performance, has remained unexplored. Here, the first experimental investigation of the degradation of CrBr3 flakes and its effect on magnetoelectric transport behavior in devices is reported. The extra magnetic compounds derived from oxidation-related degradation play a significant role in the magnetoelectric transport in CrBr3 devices, greatly affecting the magnetoresistance and conductivity. This work has important implications for studies concerning 2D magnetic materials measured, stored, and integrated into devices at ambient conditions.
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15
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Wu F, Gutiérrez-Lezama I, López-Paz SA, Gibertini M, Watanabe K, Taniguchi T, von Rohr FO, Ubrig N, Morpurgo AF. Quasi-1D Electronic Transport in a 2D Magnetic Semiconductor. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2109759. [PMID: 35191570 DOI: 10.1002/adma.202109759] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/18/2022] [Indexed: 06/14/2023]
Abstract
Electronic transport through exfoliated multilayers of CrSBr, a 2D semiconductor of interest because of its magnetic properties, is investigated. An extremely pronounced anisotropy manifesting itself in qualitative and quantitative differences of all quantities measured along the in-plane a and b crystallographic directions is found. In particular, a qualitatively different dependence of the conductivities σa and σb on temperature and gate voltage, accompanied by orders of magnitude differences in their values (σb /σa ≈ 3 × 102 to 105 at low temperature and negative gate voltage) are observed, together with a different behavior of the longitudinal magnetoresistance in the two directions and the complete absence of the Hall effect in transverse resistance measurements. These observations appear not to be compatible with a description in terms of conventional band transport of a 2D doped semiconductor. The observed phenomenology-and unambiguous signatures of a 1D van Hove singularity detected in energy-resolved photocurrent measurements-indicate that electronic transport through CrSBr multilayers is better interpreted by considering the system as formed by weakly and incoherently coupled 1D wires, than by conventional 2D band transport. It is concluded that CrSBr is the first 2D semiconductor to show distinctly quasi-1D electronic transport properties.
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Affiliation(s)
- Fan Wu
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
| | - Ignacio Gutiérrez-Lezama
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
| | - Sara A López-Paz
- Department of Chemistry, University of Zurich, Zurich, CH-8057, Switzerland
| | - Marco Gibertini
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, University of Modena and Reggio Emilia, Modena, IT-41125, Italy
- Centro S3, CNR Istituto Nanoscienze, Modena, IT-41125, Italy
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Fabian O von Rohr
- Department of Chemistry, University of Zurich, Zurich, CH-8057, Switzerland
| | - Nicolas Ubrig
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
| | - Alberto F Morpurgo
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
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16
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Abstract
We report on the optical properties from terahertz (THz) to Near-Infrared (NIR) of the layered magnetic compound CrI3 at various temperatures, both in the paramagnetic and ferromagnetic phase. In the NIR spectral range, we observe an insulating electronic gap around 1.1 eV which strongly hardens with decreasing temperature. The blue shift observed represents a record in insulating materials and it is a fingerprint of a strong electron-phonon interaction. Moreover, a further gap hardening is observed below the Curie temperature, indicating the establishment of an effective interaction between electrons and magnetic degrees of freedom in the ferromagnetic phase. Similar interactions are confirmed by the disappearance of some phonon modes in the same phase, as expected from a spin-lattice interaction theory. Therefore, the optical properties of CrI3 reveal a complex interaction among electronic, phononic and magnetic degrees of freedom, opening many possibilities for its use in 2-Dimensional heterostructures.
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17
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Wang Z, Gutiérrez-Lezama I, Dumcenco D, Ubrig N, Taniguchi T, Watanabe K, Giannini E, Gibertini M, Morpurgo AF. Magnetization dependent tunneling conductance of ferromagnetic barriers. Nat Commun 2021; 12:6659. [PMID: 34795253 PMCID: PMC8602639 DOI: 10.1038/s41467-021-26973-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 10/29/2021] [Indexed: 11/13/2022] Open
Abstract
Recent experiments on van der Waals antiferromagnets have shown that measuring the temperature (T) and magnetic field (H) dependence of the conductance allows their magnetic phase diagram to be mapped. Similarly, experiments on ferromagnetic CrBr3 barriers enabled the Curie temperature to be determined at H = 0, but a precise interpretation of the magnetoconductance data at H ≠ 0 is conceptually more complex, because at finite H there is no well-defined phase boundary. Here we perform systematic transport measurements on CrBr3 barriers and show that the tunneling magnetoconductance depends on H and T exclusively through the magnetization M(H, T) over the entire temperature range investigated. The phenomenon is reproduced by the spin-dependent Fowler–Nordheim model for tunneling, and is a direct manifestation of the spin splitting of the CrBr3 conduction band. Our analysis unveils a new approach to probe quantitatively different properties of atomically thin ferromagnetic insulators related to their magnetization by performing simple conductance measurements. Many standard techniques for investigating magnetic properties in the bulk are ill suited to atomically thin van der Waals materials. Here, Wang et al take a prototypical van der Waals ferromagnet, Chromium Bromide, and show how tunneling conductance can elucidate the material magnetic properties.
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Affiliation(s)
- Zhe Wang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Advanced Materials and Mesoscopic Physics, School of Physics, Xi'an Jiaotong University, Xi'an, 710049, China. .,Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.
| | - Ignacio Gutiérrez-Lezama
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.,Group of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Dumitru Dumcenco
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Nicolas Ubrig
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.,Group of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Enrico Giannini
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Marco Gibertini
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, University of Modena and Reggio Emilia, IT-41125, Modena, Italy.,Centro S3, CNR-Istituto Nanoscienze, IT-41125, Modena, Italy
| | - Alberto F Morpurgo
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland. .,Group of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.
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18
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Bikaljević D, González-Orellana C, Peña-Díaz M, Steiner D, Dreiser J, Gargiani P, Foerster M, Niño MÁ, Aballe L, Ruiz-Gomez S, Friedrich N, Hieulle J, Jingcheng L, Ilyn M, Rogero C, Pascual JI. Noncollinear Magnetic Order in Two-Dimensional NiBr 2 Films Grown on Au(111). ACS NANO 2021; 15:14985-14995. [PMID: 34491033 PMCID: PMC8482757 DOI: 10.1021/acsnano.1c05221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Indexed: 05/12/2023]
Abstract
Metal halides are a class of layered materials with promising electronic and magnetic properties persisting down to the two-dimensional limit. While most recent studies focused on the trihalide components of this family, the rather unexplored metal dihalides are also van der Waals layered systems with distinctive magnetic properties. Here we show that the dihalide NiBr2 grows epitaxially on a Au(111) substrate and exhibits semiconducting and magnetic behavior starting from a single layer. Through a combination of a low-temperature scanning-tunneling microscopy, low-energy electron diffraction, X-ray photoelectron spectroscopy, and photoemission electron microscopy, we identify two competing layer structures of NiBr2 coexisting at the interface and a stoichiometrically pure layer-by-layer growth beyond. Interestingly, X-ray absorption spectroscopy measurements revealed a magnetically ordered state below 27 K with in-plane magnetic anisotropy and zero-remanence in the single layer of NiBr2/Au(111), which we attribute to a noncollinear magnetic structure. The combination of such two-dimensional magnetic order with the semiconducting behavior down to the 2D limit offers the attractive perspective of using these films as ultrathin crystalline barriers in tunneling junctions and low-dimensional devices.
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Affiliation(s)
- Djuro Bikaljević
- CIC
nanoGUNE-BRTA, 20018 Donostia-San Sebastián, Spain
- Institute
of Physical Chemistry, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
| | | | - Marina Peña-Díaz
- Centro
de Física de Materiales (CSIC/UPV-EHU), 20018 Donostia-San
Sebastián, Spain
| | - Dominik Steiner
- Institute
of Physical Chemistry, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
| | - Jan Dreiser
- Paul
Scherrer Institut, Forschungsstrasse
111, CH-5232 Villigen, PSI, Switzerland
| | - Pierluigi Gargiani
- ALBA
Synchrotron Light Source, Carrer de la Llum, 2-26, 08290 Barcelona, Spain
| | - Michael Foerster
- ALBA
Synchrotron Light Source, Carrer de la Llum, 2-26, 08290 Barcelona, Spain
| | - Miguel Ángel Niño
- ALBA
Synchrotron Light Source, Carrer de la Llum, 2-26, 08290 Barcelona, Spain
| | - Lucía Aballe
- ALBA
Synchrotron Light Source, Carrer de la Llum, 2-26, 08290 Barcelona, Spain
| | - Sandra Ruiz-Gomez
- ALBA
Synchrotron Light Source, Carrer de la Llum, 2-26, 08290 Barcelona, Spain
| | | | | | - Li Jingcheng
- CIC
nanoGUNE-BRTA, 20018 Donostia-San Sebastián, Spain
| | - Maxim Ilyn
- Centro
de Física de Materiales (CSIC/UPV-EHU), 20018 Donostia-San
Sebastián, Spain
| | - Celia Rogero
- Centro
de Física de Materiales (CSIC/UPV-EHU), 20018 Donostia-San
Sebastián, Spain
- Donostia
International Physics Center DIPC, 20018 Donostia-San Sebastián, Spain
| | - José Ignacio Pascual
- CIC
nanoGUNE-BRTA, 20018 Donostia-San Sebastián, Spain
- Ikerbasque,
Basque Foundation for Science, 48013 Bilbao, Spain
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19
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Mastrippolito D, Ottaviano L, Wang J, Yang J, Gao F, Ali M, D'Olimpio G, Politano A, Palleschi S, Kazim S, Gunnella R, Di Cicco A, Sgarlata A, Strychalska-Nowak J, Klimczuk T, Cava RJ, Lozzi L, Profeta G. Emerging oxidized and defective phases in low-dimensional CrCl 3. NANOSCALE ADVANCES 2021; 3:4756-4766. [PMID: 36134325 PMCID: PMC9419748 DOI: 10.1039/d1na00401h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 06/23/2021] [Indexed: 06/16/2023]
Abstract
Two-dimensional (2D) magnets such as chromium trihalides CrX3 (X = I, Br, Cl) represent a frontier for spintronics applications and, in particular, CrCl3 has attracted research interest due its relative stability under ambient conditions without rapid degradation, as opposed to CrI3. Herein, mechanically exfoliated CrCl3 flakes are characterized at the atomic scale and the electronic structures of pristine, oxidized, and defective monolayer CrCl3 phases are investigated employing density functional theory (DFT) calculations, scanning tunneling spectroscopy (STS), core level X-ray photoemission spectroscopy (XPS), and valence band XPS and ultraviolet photoemission spectroscopy (UPS). As revealed by atomically resolved transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis, the CrCl3 flakes show spontaneous surface oxidation upon air exposure with an extrinsic long-range ordered oxidized O-CrCl3 structure and amorphous chromium oxide formation on the edges of the flakes. XPS proves that CrCl3 is thermally stable up to 200 °C having intrinsically Cl vacancy-defects whose concentration is tunable via thermal annealing up to 400 °C. DFT calculations, supported by experimental valence band analysis, indicate that pure monolayer (ML) CrCl3 is an insulator with a band gap of 2.6 eV, while the electronic structures of oxidized and Cl defective phases of ML CrCl3, extrinsically emerging in exfoliated CrCl3 flakes, show in-gap spin-polarized states and relevant modifications of the electronic band structures.
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Affiliation(s)
- Dario Mastrippolito
- Department of Physical and Chemical Sciences, University of L'Aquila Via Vetoio 10 67100 L'Aquila Italy
| | - Luca Ottaviano
- Department of Physical and Chemical Sciences, University of L'Aquila Via Vetoio 10 67100 L'Aquila Italy
- CNR-SPIN L'Aquila Via Vetoio 10 67100 L'Aquila Italy
| | - Jing Wang
- Key Laboratory of Applied Chemistry, Yanshan University Qinhuangdao 066004 P. R. China
| | - Jinjin Yang
- Key Laboratory of Applied Chemistry, Yanshan University Qinhuangdao 066004 P. R. China
| | - Faming Gao
- Key Laboratory of Applied Chemistry, Yanshan University Qinhuangdao 066004 P. R. China
| | - Mushtaq Ali
- Department of Physical and Chemical Sciences, University of L'Aquila Via Vetoio 10 67100 L'Aquila Italy
| | - Gianluca D'Olimpio
- Department of Physical and Chemical Sciences, University of L'Aquila Via Vetoio 10 67100 L'Aquila Italy
| | - Antonio Politano
- Department of Physical and Chemical Sciences, University of L'Aquila Via Vetoio 10 67100 L'Aquila Italy
- CNR-IMM Institute for Microelectronics and Microsystems VIII Strada 5 95121 Catania Italy
| | - Stefano Palleschi
- Department of Physical and Chemical Sciences, University of L'Aquila Via Vetoio 10 67100 L'Aquila Italy
| | - Shafaq Kazim
- School of Science and Technology Physics Division, University of Camerino Italy
| | - Roberto Gunnella
- School of Science and Technology Physics Division, University of Camerino Italy
| | - Andrea Di Cicco
- School of Science and Technology Physics Division, University of Camerino Italy
| | - Anna Sgarlata
- Department of Physics, Tor Vergata University of Rome Via Della Ricerca Scientifica 1 00133 Roma Italy
| | | | - Tomasz Klimczuk
- Faculty of Applied Physics and Mathematics, Gdansk University of Technology Gdansk Poland
| | | | - Luca Lozzi
- Department of Physical and Chemical Sciences, University of L'Aquila Via Vetoio 10 67100 L'Aquila Italy
| | - Gianni Profeta
- Department of Physical and Chemical Sciences, University of L'Aquila Via Vetoio 10 67100 L'Aquila Italy
- CNR-SPIN L'Aquila Via Vetoio 10 67100 L'Aquila Italy
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20
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Xu C, Zhang J, Guo Z, Zhang S, Yuan X, Wang L. A first-principles study on the electronic property and magnetic anisotropy of ferromagnetic CrOF and CrOCl monolayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:195804. [PMID: 33561851 DOI: 10.1088/1361-648x/abe477] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 02/09/2021] [Indexed: 06/12/2023]
Abstract
Two-dimensional ferromagnetic materials with large perpendicular magnetic anisotropy (PMA) hold great potential in realizing low critical switching current, high thermal stability and high density nonvolatile storage in magnetic random-access memories. Our first-principles calculations reveal that CrOF and CrOCl monolayers (MLs) are two-dimensional (2D) ferromagnetic semiconductors with out-of-plane magnetic easy axis, and PMAs of CrOF and CrOCl MLs are mainly contributed by Cr atoms. The magnetic anisotropy of CrOF and CrOCl MLs can be controlled and enhanced by applying biaxial strain. Tensile strain can further enhance PMAs of CrOF and CrOCl MLs by 82.9% and 161.0% higher than those of unstrained systems, respectively. In addition, appropriate compressive strain can switch the magnetic easy axis of CrOF and CrOCl MLs from out-of-plane direction to in-plane direction. The semiconductor natures of CrOF and CrOCl MLs robust against biaxial strain, the band gaps of these systems under biaxial strain are in the range of 1.26 eV to 2.40 eV. By applying biaxial strain, the Curie temperatures of CrOF and CrOCl MLs increase up to 282 K and 163 K, respectively. These tunable properties suggest that CrOF and CrOCl MLs have great application potentials for magnetic data storage.
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Affiliation(s)
- Chunyan Xu
- Institute for Interdisciplinary Quantum Information Technology, Jilin Engineering Normal University, Jilin Engineering Laboratory for Quantum Information Technology, Changchun 130052, People's Republic of China
| | - Jing Zhang
- Institute for Interdisciplinary Quantum Information Technology, Jilin Engineering Normal University, Jilin Engineering Laboratory for Quantum Information Technology, Changchun 130052, People's Republic of China
| | - Zexuan Guo
- Institute for Interdisciplinary Quantum Information Technology, Jilin Engineering Normal University, Jilin Engineering Laboratory for Quantum Information Technology, Changchun 130052, People's Republic of China
| | - Siqi Zhang
- Institute for Interdisciplinary Quantum Information Technology, Jilin Engineering Normal University, Jilin Engineering Laboratory for Quantum Information Technology, Changchun 130052, People's Republic of China
| | - Xiaoxi Yuan
- Institute for Interdisciplinary Quantum Information Technology, Jilin Engineering Normal University, Jilin Engineering Laboratory for Quantum Information Technology, Changchun 130052, People's Republic of China
| | - Lingrui Wang
- Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450052, People's Republic of China
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21
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Lei C, Chittari BL, Nomura K, Banerjee N, Jung J, MacDonald AH. Magnetoelectric Response of Antiferromagnetic CrI 3 Bilayers. NANO LETTERS 2021; 21:1948-1954. [PMID: 33600723 DOI: 10.1021/acs.nanolett.0c04242] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We predict that layer antiferromagnetic bilayers formed from van der Waals (vdW) materials with weak interlayer versus intralayer exchange coupling have strong magnetoelectric response that can be detected in dual-gated devices where internal displacement fields and carrier densities can be varied independently. We illustrate this strong temperature-dependent magnetoelectric response in bilayer CrI3 at charge neutrality by calculating the gate voltage-dependent total magnetization through Monte Carlo simulations and mean-field solutions of the anisotropic Heisenberg model informed from density functional theory and experimental data and present a simple model for electrical control of magnetism by electrostatic doping.
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Affiliation(s)
- Chao Lei
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Bheema L Chittari
- Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Kentaro Nomura
- Institute for Materials Research, Tohoku University, Sendai Aoba-ku 980-8577, Japan
| | - Nepal Banerjee
- Department of Physics, University of Seoul, Seoul 02504, Korea
- Department of Smart Cities, University of Seoul, Seoul 02504, Korea
| | - Jeil Jung
- Department of Physics, University of Seoul, Seoul 02504, Korea
- Department of Smart Cities, University of Seoul, Seoul 02504, Korea
| | - Allan H MacDonald
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, United States
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22
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Shao YC, Karki B, Huang W, Feng X, Sumanasekera G, Guo JH, Chuang YD, Freelon B. Spectroscopic Determination of Key Energy Scales for the Base Hamiltonian of Chromium Trihalides. J Phys Chem Lett 2021; 12:724-731. [PMID: 33400873 DOI: 10.1021/acs.jpclett.0c03476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The van der Waals (vdW) chromium trihalides (CrX3) exhibit field-tunable, two-dimensional magnetic orders that vary with the halogen species and the number of layers. Their magnetic ground states with proximity in energies are sensitive to the degree of ligand-metal (p-d) hybridization and relevant modulations in the Cr d-orbital interactions. We use soft X-ray absorption (XAS) and resonant inelastic X-ray scattering (RIXS) spectroscopy at Cr L-edge along with the atomic multiplet simulations to determine the key energy scales such as the crystal field 10 Dq and interorbital Coulomb interactions under different ligand metal charge transfer (LMCT) in CrX3 (X= Cl, Br, and I). Through this systematic study, we show that our approach compared to the literature has yielded a set of more reliably determined parameters for establishing a base Hamiltonian for CrX3.
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Affiliation(s)
- Y C Shao
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Physics, University of Houston, Houston, Texas 77204, United States
| | - B Karki
- Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40292, United States
| | - W Huang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and InformationTechnology, Chinese Academy of Sciences, Shanghai 200050, China
| | - X Feng
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - G Sumanasekera
- Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40292, United States
| | - J-H Guo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Y-D Chuang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - B Freelon
- Department of Physics, University of Houston, Houston, Texas 77204, United States
- Texas Center for Superconductivity, University of Houston, Houston Texas 77204, United States
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23
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Mukherjee A, Shayan K, Li L, Shan J, Mak KF, Vamivakas AN. Observation of site-controlled localized charged excitons in CrI 3/WSe 2 heterostructures. Nat Commun 2020; 11:5502. [PMID: 33127925 PMCID: PMC7599320 DOI: 10.1038/s41467-020-19262-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 09/30/2020] [Indexed: 11/09/2022] Open
Abstract
Isolated spins are the focus of intense scientific exploration due to their potential role as qubits for quantum information science. Optical access to single spins, demonstrated in III-V semiconducting quantum dots, has fueled research aimed at realizing quantum networks. More recently, quantum emitters in atomically thin materials such as tungsten diselenide have been demonstrated to host optically addressable single spins by means of electrostatic doping the localized excitons. Electrostatic doping is not the only route to charging localized quantum emitters and another path forward is through band structure engineering using van der Waals heterojunctions. Critical to this second approach is to interface tungsten diselenide with other van der Waals materials with relative band-alignments conducive to the phenomenon of charge transfer. In this work we show that the Type-II band-alignment between tungsten diselenide and chromium triiodide can be exploited to excite localized charged excitons in tungsten diselenide. Leveraging spin-dependent charge transfer in the device, we demonstrate spin selectivity in the preparation of the spin-valley state of localized single holes. Combined with the use of strain-inducing nanopillars to coordinate the spatial location of tungsten diselenide quantum emitters, we uncover the possibility of realizing large-scale deterministic arrays of optically addressable spin-valley holes in a solid state platform.
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Affiliation(s)
- Arunabh Mukherjee
- The Institute of Optics, University of Rochester, Rochester, NY, USA
| | - Kamran Shayan
- The Institute of Optics, University of Rochester, Rochester, NY, USA
| | - Lizhong Li
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.,Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA
| | - Jie Shan
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.,Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.,Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA
| | - Kin Fai Mak
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.,Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.,Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA
| | - A Nick Vamivakas
- The Institute of Optics, University of Rochester, Rochester, NY, USA. .,Materials Science, University of Rochester, Rochester, NY, USA. .,Department of Physics and Astronomy, University of Rochester, Rochester, NY, USA. .,Center for Coherence and Quantum Optics, University of Rochester, Rochester, NY, USA.
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24
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Yoon J, Lesne E, Sklarek K, Sheckelton J, Pasco C, Parkin SSP, McQueen TM, Ali MN. Anomalous thickness-dependent electrical conductivity in van der Waals layered transition metal halide, Nb 3Cl 8. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:304004. [PMID: 32213671 DOI: 10.1088/1361-648x/ab832b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Understanding the electronic transport properties of layered, van der Waals transition metal halides (TMHs) and chalcogenides is a highly active research topic today. Of particular interest is the evolution of those properties with changing thickness as the 2D limit is approached. Here, we present the electrical conductivity of exfoliated single crystals of the TMH, cluster magnet, Nb3Cl8, over a wide range of thicknesses both with and without hexagonal boron nitride (hBN) encapsulation. The conductivity is found to increase by more than three orders of magnitude when the thickness is decreased from 280 µm to 5 nm, at 300 K. At low temperatures and below ∼50 nm, the conductance becomes thickness independent, implying surface conduction is dominating. Temperature dependent conductivity measurements indicate Nb3Cl8 is an insulator, however, the effective activation energy decreases from a bulk value of 310 meV to 140 meV by 5 nm. X-ray photoelectron spectroscopy (XPS) shows mild surface oxidation in devices without hBN capping, however, no significant difference in transport is observed when compared to the capped devices, implying the thickness dependent transport behavior is intrinsic to the material. A conduction mechanism comprised of a higher conductivity surface channel in parallel with a lower conductivity interlayer channel is discussed.
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Affiliation(s)
- Jiho Yoon
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle 06120, Germany
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25
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Serri M, Cucinotta G, Poggini L, Serrano G, Sainctavit P, Strychalska-Nowak J, Politano A, Bonaccorso F, Caneschi A, Cava RJ, Sessoli R, Ottaviano L, Klimczuk T, Pellegrini V, Mannini M. Enhancement of the Magnetic Coupling in Exfoliated CrCl 3 Crystals Observed by Low-Temperature Magnetic Force Microscopy and X-ray Magnetic Circular Dichroism. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2000566. [PMID: 32390212 DOI: 10.1002/adma.202000566] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 03/21/2020] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
Magnetic crystals formed by 2D layers interacting by weak van der Waals forces are currently a hot research topic. When these crystals are thinned to nanometric size, they can manifest strikingly different magnetic behavior compared to the bulk form. This can be the result of, for example, quantum electronic confinement effects, the presence of defects, or pinning of the crystallographic structure in metastable phases induced by the exfoliation process. In this work, an investigation of the magnetism of micromechanically cleaved CrCl3 flakes with thickness >10 nm is performed. These flakes are characterized by superconducting quantum interference device magnetometry, surface-sensitive X-ray magnetic circular dichroism, and spatially resolved magnetic force microscopy. The results highlight an enhancement of the CrCl3 antiferromagnetic interlayer interaction that appears to be independent of the flake size when the thickness is tens of nanometers. The estimated exchange field is 9 kOe, representing an increase of ≈900% compared to the one of the bulk crystals. This effect can be attributed to the pinning of the high-temperature monoclinic structure, as recently suggested by polarized Raman spectroscopy investigations in thin (8-35 nm) CrCl3 flakes.
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Affiliation(s)
- Michele Serri
- Istituto Italiano di Tecnologia-Graphene Labs, via Morego 30, Genova, 16163, Italy
| | - Giuseppe Cucinotta
- Chemistry Department "U. Schiff" and INSTM RU, Università degli studi di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, 50019, Italy
| | - Lorenzo Poggini
- Chemistry Department "U. Schiff" and INSTM RU, Università degli studi di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, 50019, Italy
| | - Giulia Serrano
- Chemistry Department "U. Schiff" and INSTM RU, Università degli studi di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, 50019, Italy
- Department of Industrial Engineering DIEF, and INSTM RU, Università degli Studi di Firenze, Via di S. Marta 3, Firenze, 50139, Italy
| | - Philippe Sainctavit
- Institut de Mineralogie, de Physique des Materiaux et de Cosmochimie UMR 7590, CNRS, Sorbonne Université, MNHN, Paris, F-75005, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP 48, Gif-sur-Yvette, F-91192, France
| | - Judyta Strychalska-Nowak
- Faculty of Applied Physics and Mathematics, Advanced Materials Center Gdansk University of Technology, Gdansk, 80-233, Poland
| | - Antonio Politano
- Dipartimento di Scienze Fisiche e Chimiche (DSFC), Università dell'Aquila, Via Vetoio 10, L'Aquila, 67100, Italy
- CNR-IMM Istituto per la Microelettronica e Microsistemi, VIII strada 5, Catania, I-95121, Italy
| | - Francesco Bonaccorso
- Istituto Italiano di Tecnologia-Graphene Labs, via Morego 30, Genova, 16163, Italy
- BeDimensional Spa, Genoa, 16163, Italy
| | - Andrea Caneschi
- Department of Industrial Engineering DIEF, and INSTM RU, Università degli Studi di Firenze, Via di S. Marta 3, Firenze, 50139, Italy
| | - Robert J Cava
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Roberta Sessoli
- Chemistry Department "U. Schiff" and INSTM RU, Università degli studi di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, 50019, Italy
| | - Luca Ottaviano
- Dipartimento di Scienze Fisiche e Chimiche (DSFC), Università dell'Aquila, Via Vetoio 10, L'Aquila, 67100, Italy
- CNR-SPIN UoS L'Aquila, Via Vetoio 46, L'Aquila, 67100, Italy
| | - Tomasz Klimczuk
- Faculty of Applied Physics and Mathematics, Advanced Materials Center Gdansk University of Technology, Gdansk, 80-233, Poland
| | - Vittorio Pellegrini
- Istituto Italiano di Tecnologia-Graphene Labs, via Morego 30, Genova, 16163, Italy
- BeDimensional Spa, Genoa, 16163, Italy
| | - Matteo Mannini
- Chemistry Department "U. Schiff" and INSTM RU, Università degli studi di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, 50019, Italy
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26
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Albaridy R, Manchon A, Schwingenschlögl U. Tunable magnetic anisotropy in Cr-trihalide Janus monolayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:355702. [PMID: 32469846 DOI: 10.1088/1361-648x/ab8986] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 04/15/2020] [Indexed: 06/11/2023]
Abstract
Achieving a two-dimensional material with tunable magnetic anisotropy is highly desirable, especially if it is complemented with out-of-plane electric polarization, as this could provide a versatile platform for spintronic and multifunctional devices. Using first principles calculations, we demonstrate that the magnetic anisotropy of Cr-trihalides become highly sensitive to mechanical strain upon structural inversion symmetry breaking through the realization of Janus monolayers. This remarkable feature, absent in pristine Cr-trihalide monolayers, enables mechanical control of the direction of the easy axis: biaxial compressive/tensile strain supports in-plane/out-of-plane orientation of the easy axis. The magnetic exchange itself shows higher sensitivity to compressive than to tensile strain, while in general the Janus monolayers maintain ferromagnetic ordering in the studied range of strain.
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Affiliation(s)
- Rehab Albaridy
- Physical Sciences and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Aurelien Manchon
- Physical Sciences and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Udo Schwingenschlögl
- Physical Sciences and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
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27
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Herman TJ, Keogh JP, Ziurys LM. Millimeter/sub-mm spectroscopy of the CrBr radical in the high spin X 6Σ + state. J Chem Phys 2019; 151:194301. [DOI: 10.1063/1.5125013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- T. J. Herman
- Department of Chemistry and Biochemistry, Department of Astronomy, and Steward Observatory, University of Arizona, 1305 E. 4th Street, Tucson, Arizona 85719, USA
| | - J. P. Keogh
- Department of Chemistry and Biochemistry, Department of Astronomy, and Steward Observatory, University of Arizona, 1305 E. 4th Street, Tucson, Arizona 85719, USA
| | - L. M. Ziurys
- Department of Chemistry and Biochemistry, Department of Astronomy, and Steward Observatory, University of Arizona, 1305 E. 4th Street, Tucson, Arizona 85719, USA
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28
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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: 106] [Impact Index Per Article: 21.2] [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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29
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Gibertini M, Koperski M, Morpurgo AF, Novoselov KS. Magnetic 2D materials and heterostructures. NATURE NANOTECHNOLOGY 2019; 14:408-419. [PMID: 31065072 DOI: 10.1038/s41565-019-0438-6] [Citation(s) in RCA: 444] [Impact Index Per Article: 88.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 03/28/2019] [Indexed: 05/22/2023]
Abstract
The family of two-dimensional (2D) materials grows day by day, hugely expanding the scope of possible phenomena to be explored in two dimensions, as well as the possible van der Waals (vdW) heterostructures that one can create. Such 2D materials currently cover a vast range of properties. Until recently, this family has been missing one crucial member: 2D magnets. The situation has changed over the past 2 years with the introduction of a variety of atomically thin magnetic crystals. Here we will discuss the difference between magnetic states in 2D materials and in bulk crystals and present an overview of the 2D magnets that have been explored recently. We will focus on the case of the two most studied systems-semiconducting CrI3 and metallic Fe3GeTe2-and illustrate the physical phenomena that have been observed. Special attention will be given to the range of new van der Waals heterostructures that became possible with the appearance of 2D magnets, offering new perspectives in this rapidly expanding field.
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Affiliation(s)
- M Gibertini
- Department of Quantum Matter Physics, University of Geneva, Geneva, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - M Koperski
- School of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - A F Morpurgo
- Department of Quantum Matter Physics, University of Geneva, Geneva, Switzerland
- Group of Applied Physics, University of Geneva, Geneva, Switzerland
| | - K S Novoselov
- School of Physics and Astronomy, University of Manchester, Manchester, UK.
- National Graphene Institute, University of Manchester, Manchester, UK.
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30
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Paudel TR, Tsymbal EY. Spin Filtering in CrI 3 Tunnel Junctions. ACS APPLIED MATERIALS & INTERFACES 2019; 11:15781-15787. [PMID: 30964639 DOI: 10.1021/acsami.9b01942] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The recently discovered magnetism of two-dimensional (2D) van der Waals crystals has attracted a lot of attention. Among these materials is CrI3, a magnetic semiconductor, exhibiting transitions between ferromagnetic and antiferromagnetic orderings under the influence of an applied magnetic field. Here, using first-principles methods based on density functional theory, we explore spin-dependent transport in tunnel junctions formed of face-centered cubic Cu(111) electrodes and a CrI3 tunnel barrier. We find about 100% spin polarization of the tunneling current for a ferromagnetically ordered four-monolayer CrI3 and a tunneling magnetoresistance of about 3000% associated with a change of magnetic ordering in CrI3. This behavior is understood in terms of the spin and wave-vector-dependent evanescent states in CrI3, which control the tunneling conductance. We find a sizable charge transfer from Cu to CrI3, which adds new features to the mechanism of spin filtering in CrI3-based tunnel junctions. Our results elucidate the mechanisms of spin filtering in CrI3 tunnel junctions and provide important insights for the design of magnetoresistive devices based on 2D magnetic crystals.
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Affiliation(s)
- Tula R Paudel
- Department of Physics and Astronomy & Nebraska Center for Materials and Nanoscience , University of Nebraska , Lincoln , Nebraska 68588 , United States
| | - Evgeny Y Tsymbal
- Department of Physics and Astronomy & Nebraska Center for Materials and Nanoscience , University of Nebraska , Lincoln , Nebraska 68588 , United States
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31
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Chen L, Chung JH, Gao B, Chen T, Stone MB, Kolesnikov AI, Huang Q, Dai P. Topological Spin Excitations in Honeycomb Ferromagnet CrI 3 . PHYSICAL REVIEW. X 2018; 8:10.1103/PhysRevX.8.041028. [PMID: 38915421 PMCID: PMC11194793 DOI: 10.1103/physrevx.8.041028] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
In two-dimensional honeycomb ferromagnets, bosonic magnon quasiparticles (spin waves) may either behave as massless Dirac fermions or form topologically protected edge states. The key ingredient defining their nature is the next-nearest-neighbor Dzyaloshinskii-Moriya interaction that breaks the inversion symmetry of the lattice and discriminates chirality of the associated spin-wave excitations. Using inelastic neutron scattering, we find that spin waves of the insulating honeycomb ferromagnetCrI 3 (T C = 61 K ) have two distinctive bands of ferromagnetic excitations separated by a ∼4 meV gap at the Dirac points. These results can only be understood by considering a Heisenberg Hamiltonian with Dzyaloshinskii-Moriya interaction, thus providing experimental evidence that spin waves inCrI 3 can have robust topological properties potentially useful for dissipationless spintronic applications.
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Affiliation(s)
- Lebing Chen
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Jae-Ho Chung
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Department of Physics, Korea University, Seoul 02841, Korea
| | - Bin Gao
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Tong Chen
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Matthew B. Stone
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | | | - Qingzhen Huang
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
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32
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Kim HH, Yang B, Patel T, Sfigakis F, Li C, Tian S, Lei H, Tsen AW. One Million Percent Tunnel Magnetoresistance in a Magnetic van der Waals Heterostructure. NANO LETTERS 2018; 18:4885-4890. [PMID: 30001134 DOI: 10.1021/acs.nanolett.8b01552] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We report the observation of a very large negative magnetoresistance effect in a van der Waals tunnel junction incorporating a thin magnetic semiconductor, CrI3, as the active layer. At constant voltage bias, current increases by nearly one million percent upon application of a 2 T field. The effect arises from a change between antiparallel to parallel alignment of spins across the different CrI3 layers. Our results elucidate the nature of the magnetic state in ultrathin CrI3 and present new opportunities for spintronics based on two-dimensional materials.
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Affiliation(s)
- Hyun Ho Kim
- Institute for Quantum Computing , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
- Department of Chemistry , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
| | - Bowen Yang
- Institute for Quantum Computing , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
- Department of Physics and Astronomy , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
| | - Tarun Patel
- Institute for Quantum Computing , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
- Department of Physics and Astronomy , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
| | - Francois Sfigakis
- Institute for Quantum Computing , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
- Department of Chemistry , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
| | - Chenghe Li
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices , Renmin University of China , Beijing 100872 , China
| | - Shangjie Tian
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices , Renmin University of China , Beijing 100872 , China
| | - Hechang Lei
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices , Renmin University of China , Beijing 100872 , China
| | - Adam W Tsen
- Institute for Quantum Computing , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
- Department of Chemistry , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
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33
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Jiang S, Li L, Wang Z, Mak KF, Shan J. Controlling magnetism in 2D CrI 3 by electrostatic doping. NATURE NANOTECHNOLOGY 2018; 13:549-553. [PMID: 29736035 DOI: 10.1038/s41565-018-0135-x] [Citation(s) in RCA: 345] [Impact Index Per Article: 57.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 04/03/2018] [Indexed: 05/22/2023]
Abstract
The atomic thickness of two-dimensional materials provides a unique opportunity to control their electrical1 and optical2 properties as well as to drive the electronic phase transitions3 by electrostatic doping. The discovery of two-dimensional magnetic materials4-10 has opened up the prospect of the electrical control of magnetism and the realization of new functional devices11. A recent experiment based on the linear magneto-electric effect has demonstrated control of the magnetic order in bilayer CrI3 by electric fields12. However, this approach is limited to non-centrosymmetric materials11,13-16 magnetically biased near the antiferromagnet-ferromagnet transition. Here, we demonstrate control of the magnetic properties of both monolayer and bilayer CrI3 by electrostatic doping using CrI3-graphene vertical heterostructures. In monolayer CrI3, doping significantly modifies the saturation magnetization, coercive force and Curie temperature, showing strengthened/weakened magnetic order with hole/electron doping. Remarkably, in bilayer CrI3, the electron doping above ~2.5 × 1013 cm-2 induces a transition from an antiferromagnetic to a ferromagnetic ground state in the absence of a magnetic field. The result reveals a strongly doping-dependent interlayer exchange coupling, which enables robust switching of magnetization in bilayer CrI3 by small gate voltages.
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Affiliation(s)
- Shengwei Jiang
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA
| | - Lizhong Li
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Zefang Wang
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Department of Physics, Penn State University, University Park, PA, USA
| | - Kin Fai Mak
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
| | - Jie Shan
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
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Wang Z, Gutiérrez-Lezama I, Ubrig N, Kroner M, Gibertini M, Taniguchi T, Watanabe K, Imamoğlu A, Giannini E, Morpurgo AF. Very large tunneling magnetoresistance in layered magnetic semiconductor CrI 3. Nat Commun 2018; 9:2516. [PMID: 29955066 PMCID: PMC6023911 DOI: 10.1038/s41467-018-04953-8] [Citation(s) in RCA: 201] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 06/05/2018] [Indexed: 11/30/2022] Open
Abstract
Magnetic layered van der Waals crystals are an emerging class of materials giving access to new physical phenomena, as illustrated by the recent observation of 2D ferromagnetism in Cr2Ge2Te6 and CrI3. Of particular interest in semiconductors is the interplay between magnetism and transport, which has remained unexplored. Here we report magneto-transport measurements on exfoliated CrI3 crystals. We find that tunneling conduction in the direction perpendicular to the crystalline planes exhibits a magnetoresistance as large as 10,000%. The evolution of the magnetoresistance with magnetic field and temperature reveals that the phenomenon originates from multiple transitions to different magnetic states, whose possible microscopic nature is discussed on the basis of all existing experimental observations. This observed dependence of the conductance of a tunnel barrier on its magnetic state is a phenomenon that demonstrates the presence of a strong coupling between transport and magnetism in magnetic van der Waals semiconductors.
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Affiliation(s)
- Zhe Wang
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.
- Group of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.
| | - Ignacio Gutiérrez-Lezama
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
- Group of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Nicolas Ubrig
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
- Group of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Martin Kroner
- Institute of Quantum Electronics, ETH Zürich, CH-8093, Zürich, Switzerland
| | - Marco Gibertini
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
- Group of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Takashi Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Kenji Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Ataç Imamoğlu
- Institute of Quantum Electronics, ETH Zürich, CH-8093, Zürich, Switzerland
| | - Enrico Giannini
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Alberto F Morpurgo
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.
- Group of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.
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35
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Abramchuk M, Jaszewski S, Metz KR, Osterhoudt GB, Wang Y, Burch KS, Tafti F. Controlling Magnetic and Optical Properties of the van der Waals Crystal CrCl 3-x Br x via Mixed Halide Chemistry. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1801325. [PMID: 29719069 DOI: 10.1002/adma.201801325] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 03/29/2018] [Indexed: 06/08/2023]
Abstract
Magnetic van der Waals (vdW) materials are the centerpiece of atomically thin devices with spintronic and optoelectronic functions. Exploring new chemistry paths to tune their magnetic and optical properties enables significant progress in fabricating heterostructures and ultracompact devices by mechanical exfoliation. The key parameter to sustain ferromagnetism in 2D is magnetic anisotropy-a tendency of spins to align in a certain crystallographic direction known as easy-axis. In layered materials, two limits of easy-axis are in-plane (XY) and out-of-plane (Ising). Light polarization and the helicity of topological states can couple to magnetic anisotropy with promising photoluminescence or spin-orbitronic functions. Here, a unique experiment is designed to control the easy-axis, the magnetic transition temperature, and the optical gap simultaneously in a series of CrCl3-x Brx crystals between CrCl3 with XY and CrBr3 with Ising anisotropy. The easy-axis is controlled between the two limits by varying spin-orbit coupling with the Br content in CrCl3-x Brx . The optical gap, magnetic transition temperature, and interlayer spacing are all tuned linearly with x. This is the first report of controlling exchange anisotropy in a layered crystal and the first unveiling of mixed halide chemistry as a powerful technique to produce functional materials for spintronic devices.
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Affiliation(s)
- Mykola Abramchuk
- Departments of Physics and Chemistry, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA, 02467, USA
| | - Samantha Jaszewski
- Departments of Physics and Chemistry, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA, 02467, USA
| | - Kenneth R Metz
- Departments of Physics and Chemistry, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA, 02467, USA
| | - Gavin B Osterhoudt
- Departments of Physics and Chemistry, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA, 02467, USA
| | - Yiping Wang
- Departments of Physics and Chemistry, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA, 02467, USA
| | - Kenneth S Burch
- Departments of Physics and Chemistry, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA, 02467, USA
| | - Fazel Tafti
- Departments of Physics and Chemistry, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA, 02467, USA
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36
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Owerre SA. Dirac Magnon Nodal Loops in Quasi-2D Quantum Magnets. Sci Rep 2017; 7:6931. [PMID: 28761131 PMCID: PMC5537300 DOI: 10.1038/s41598-017-07276-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 06/23/2017] [Indexed: 11/10/2022] Open
Abstract
In this report, we propose a new concept of one-dimensional (1D) closed lines of Dirac magnon nodes in two-dimensional (2D) momentum space of quasi-2D quantum magnetic systems. They are termed "2D Dirac magnon nodal-line loops". We utilize the bilayer honeycomb ferromagnets with intralayer coupling J and interlayer coupling J L , which is realizable in the honeycomb chromium compounds CrX3 (X ≡ Br, Cl, and I). However, our results can also exist in other layered quasi-2D quantum magnetic systems. Here, we show that the magnon bands of the bilayer honeycomb ferromagnets overlap for J L ≠ 0 and form 1D closed lines of Dirac magnon nodes in 2D momentum space. The 2D Dirac magnon nodal-line loops are topologically protected by inversion and time-reversal symmetry. Furthermore, we show that they are robust against weak Dzyaloshinskii-Moriya interaction Δ DM < J L and possess chiral magnon edge modes.
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Affiliation(s)
- S A Owerre
- Perimeter Institute for Theoretical Physics, 31 Caroline St. N., Waterloo, Ontario, N2L 2Y5, Canada.
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37
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Crystal and Magnetic Structures in Layered, Transition Metal Dihalides and Trihalides. CRYSTALS 2017. [DOI: 10.3390/cryst7050121] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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