1
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Truc B, Usai P, Pennacchio F, Berruto G, Claude R, Madan I, Sala V, LaGrange T, Vanacore GM, Benhabib S, Carbone F. Ultrafast generation of hidden phases via energy-tuned electronic photoexcitation in magnetite. Proc Natl Acad Sci U S A 2024; 121:e2316438121. [PMID: 38900799 PMCID: PMC11214049 DOI: 10.1073/pnas.2316438121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 04/26/2024] [Indexed: 06/22/2024] Open
Abstract
Phase transitions occurring in nonequilibrium conditions can evolve through high-energy intermediate states inaccessible via equilibrium adiabatic conditions. Because of the subtle nature of such hidden phases, their direct observation is extremely challenging and requires simultaneous visualization of matter at subpicoseconds and subpicometer scales. Here, we show that a magnetite crystal in the vicinity of its metal-to-insulator transition evolves through different hidden states when controlled via energy-tuned ultrashort laser pulses. By directly monitoring magnetite's crystal structure with ultrafast electron diffraction, we found that upon near-infrared (800 nm) excitation, the trimeron charge/orbital ordering pattern is destroyed in favor of a phase-separated state made of cubic-metallic and monoclinic-insulating regions. On the contrary, visible light (400 nm) activates a photodoping charge transfer process that further promotes the long-range order of the trimerons by stabilizing the charge density wave fluctuations, leading to the reinforcement of the monoclinic insulating phase. Our results demonstrate that magnetite's structure can evolve through completely different metastable hidden phases that can be reached long after the initial excitation has relaxed, breaking ground for a protocol to control emergent properties of matter.
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Affiliation(s)
- B. Truc
- School of Basic Sciences, Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
| | - P. Usai
- School of Basic Sciences, Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
| | - F. Pennacchio
- School of Basic Sciences, Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
| | - G. Berruto
- School of Basic Sciences, Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
| | - R. Claude
- School of Basic Sciences, Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
| | - I. Madan
- School of Basic Sciences, Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
| | - V. Sala
- Dipartimento di Fisica, Politecnico di Milano, Milano20133, Italy
| | - T. LaGrange
- School of Basic Sciences, Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
| | - G. M. Vanacore
- School of Basic Sciences, Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
- Department of Materials Science, Laboratory of Ultrafast Microscopy for Nanoscale Dynamics, University of Milano-Bicocca, Milan20125, Italy
| | - S. Benhabib
- School of Basic Sciences, Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
- Centre national de la recherche scientifique, Laboratoire de Physique des Solides, Université Paris-Saclay, Orsay91405, France
| | - F. Carbone
- School of Basic Sciences, Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
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2
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Wang W, Li J, Liang Z, Wu L, Lozano PM, Komarek AC, Shen X, Reid AH, Wang X, Li Q, Yin W, Sun K, Robinson IK, Zhu Y, Dean MP, Tao J. Verwey transition as evolution from electronic nematicity to trimerons via electron-phonon coupling. SCIENCE ADVANCES 2023; 9:eadf8220. [PMID: 37294769 PMCID: PMC10256157 DOI: 10.1126/sciadv.adf8220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 05/04/2023] [Indexed: 06/11/2023]
Abstract
Understanding the driving mechanisms behind metal-insulator transitions (MITs) is a critical step toward controlling material's properties. Since the proposal of charge order-induced MIT in magnetite Fe3O4 in 1939 by Verwey, the nature of the charge order and its role in the transition have remained elusive. Recently, a trimeron order was found in the low-temperature structure of Fe3O4; however, the expected transition entropy change in forming trimeron is greater than the observed value, which arises a reexamination of the ground state in the high-temperature phase. Here, we use electron diffraction to unveil that a nematic charge order on particular Fe sites emerges in the high-temperature structure of bulk Fe3O4 and that, upon cooling, a competitive intertwining of charge and lattice orders arouses the Verwey transition. Our findings discover an unconventional type of electronic nematicity in correlated materials and offer innovative insights into the transition mechanism in Fe3O4 via the electron-phonon coupling.
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Affiliation(s)
- Wei Wang
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Jun Li
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Zhixiu Liang
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Lijun Wu
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Pedro M. Lozano
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800, USA
| | - Alexander C. Komarek
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Street 40, 01187 Dresden, Germany
| | - Xiaozhe Shen
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Alex H. Reid
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Xijie Wang
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Qiang Li
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800, USA
| | - Weiguo Yin
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Kai Sun
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ian K. Robinson
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA
- London Centre for Nanotechnology, University College, London WC1E 6BT, UK
| | - Yimei Zhu
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Mark P.M. Dean
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Jing Tao
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY 11973, USA
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3
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Wan K, Jiang B, Tan T, Wang H, Liang M. Surface-Mediated Production of Complexed •OH Radicals and FeO Species as a Mechanism for Iron Oxide Peroxidase-Like Nanozymes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2204372. [PMID: 36316230 DOI: 10.1002/smll.202204372] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 09/15/2022] [Indexed: 06/16/2023]
Abstract
Fe3 O4 nanoparticles (NPs) with intrinsic peroxidase-like properties have attracted significant interest, although limited information is available on the definite catalytic mechanism. Here, it is shown that both complexed hydroxyl radicals (•OH) and high-valent FeO species are attributed primarily to the peroxidase-like catalytic activity of Fe3 O4 NPs under acid conditions rather than only being caused by free •OH radicals generated through the iron-driven Fenton/Haber-Weiss reactions as previously thought. The low energy barrier of OO bond dissociation of H2 O2 /•OOH (0.14 eV) and the high oxidation activity of surface FeO (0 eV) due to the reduced state of Fe on the surface of Fe3 O4 NPs thermodynamically favor both the •OH and FeO pathways. By contrast, high-valent FeO species are the key intermediates in the catalytic cycles of natural peroxidase enzymes. Moreover, it is demonstrated that the enzyme-like activity of Fe3 O4 NPs can be rationally regulated by modulating the size, surface structure, and valence of active metal atoms in the light of this newly proposed nanozyme catalytic mechanism.
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Affiliation(s)
- Kaiwei Wan
- Experimental Center of Advanced Materials, School of Materials Science & Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
- Laboratory of Theoretical and Computational Nanoscience, CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, P. R. China
| | - Bing Jiang
- Experimental Center of Advanced Materials, School of Materials Science & Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Ting Tan
- Laboratory of Theoretical and Computational Nanoscience, CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Hui Wang
- Laboratory of Theoretical and Computational Nanoscience, CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, P. R. China
| | - Minmin Liang
- Experimental Center of Advanced Materials, School of Materials Science & Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
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4
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Zhang S, Li K, Ma Y, Guo F, Jiang C, Liang Z, Bu Y, Zhang J. Density Functional Studies on the Atomistic Structure and Properties of Iron Oxides: A Parametric Study. MATERIALS (BASEL, SWITZERLAND) 2022; 15:8316. [PMID: 36499813 PMCID: PMC9740064 DOI: 10.3390/ma15238316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/15/2022] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
With the aim to find the best simulation routine to accurately predict the ground-state structures and properties of iron oxides (hematite, magnetite, and wustite) using density functional theory (DFT) with Hubbard-U correction, a significant amount of DFT calculations were conducted to investigate the influence of various simulation parameters (energy cutoff, K-point, U value, magnetization setting, smearing value, etc.) and pseudopotentials on the structures and properties of iron oxides. With optimized simulation parameters, the obtained equation of state, lattice constant, bulk moduli, and band gap is much closer to the experimental values compared with previous studies. Due to the strong coupling between the 2p orbital of O and the 3d orbital of Fe, it was found that Hubbard-U correction obviously improved the results for all three kinds of iron oxides including magnetite which has not yet been tested with U correction before, but the U value should be different for different oxides (3 ev, 4 ev, 4 ev for hematite, magnetite, and wustite, respectively). Two kinds of spin magnetism settings for FeO are considered, which should be chosen according to different calculation purposes. The detailed relationship between the parameter settings and the atomic structures and properties were analyzed, and the general principles for future DFT calculation of iron oxides were provided.
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Affiliation(s)
- Shujie Zhang
- School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Kejiang Li
- School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yan Ma
- Max−Planck−Institut für Eisenforschung, Max−Planck−Straße 1, 40237 Düsseldorf, Germany
| | - Feng Guo
- School of Physical Science and Information Technology, Liaocheng University, Liaocheng 252000, China
| | - Chunhe Jiang
- School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Zeng Liang
- School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yushan Bu
- School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Jianliang Zhang
- School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
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5
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Shutikova MI, Stegailov VV. Frenkel pair formation energy for cubic Fe 3O 4in DFT + U calculations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:475701. [PMID: 36137505 DOI: 10.1088/1361-648x/ac9440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 09/22/2022] [Indexed: 06/16/2023]
Abstract
The cubic phase of magnetite is stabilized above the Verwey transition temperature of about 120 K via a complex electron-phonon interaction that is still not very well understood. In this work using the DFT + U method we describe our attempt to calculate point defect formation energies for this cubic phase in the static approximation. The electronic structure calculations and atomic relaxation peculiarities are discussed in this context. Only the cubic phase model with a small band gap and charge disproportionation (Fe2+/Fe3+) gives an adequate point defect formation energies, not the semi-metallic model. The relaxation of the local defect atomic structure and the relaxation of the surrounding crystal matrix are analyzed. Point defects cause only local perturbations of atomic positions and charge-orbital order. After analysis of the supercell size effects for up to 448 atoms, we justify the use of small supercells with 56 atoms to make calculations for the cubic phase. The extensive experimental results of Dieckmannet alon defects in magnetite at high temperature are deployed for comparison of our DFT + U results on Frenkel pair formation energies.
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Affiliation(s)
- M I Shutikova
- Joint Institute for High Temperatures of the Russian Academy of Sciences, Izhorskaya 13 Building 2, Moscow 125412, Russia
- Moscow Institute of Physics and Technologies (National Research University), Institutskij pereulok 9, Dolgoprudny, Moscow Region 141700, Russia
| | - V V Stegailov
- Joint Institute for High Temperatures of the Russian Academy of Sciences, Izhorskaya 13 Building 2, Moscow 125412, Russia
- Moscow Institute of Physics and Technologies (National Research University), Institutskij pereulok 9, Dolgoprudny, Moscow Region 141700, Russia
- HSE University, Myasnitskaya Ulitsa 20, Moscow 101000, Russia
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6
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Layek S, Greenberg E, Chariton S, Bykov M, Bykova E, Trots DM, Kurnosov AV, Chuvashova I, Ovsyannikov SV, Leonov I, Rozenberg GK. Verwey-Type Charge Ordering and Site-Selective Mott Transition in Fe 4O 5 under Pressure. J Am Chem Soc 2022; 144:10259-10269. [PMID: 35649281 PMCID: PMC9204770 DOI: 10.1021/jacs.2c00895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Indexed: 11/28/2022]
Abstract
The metal-insulator transition driven by electronic correlations is one of the most fundamental concepts in condensed matter. In mixed-valence compounds, this transition is often accompanied by charge ordering (CO), resulting in the emergence of complex phases and unusual behaviors. The famous example is the archetypal mixed-valence mineral magnetite, Fe3O4, exhibiting a complex charge-ordering below the Verwey transition, whose nature has been a subject of long-time debates. In our study, using high-resolution X-ray diffraction supplemented by resistance measurements and DFT+DMFT calculations, the electronic, magnetic, and structural properties of recently synthesized mixed-valence Fe4O5 are investigated under pressure to ∼100 GPa. Our calculations, consistent with experiment, reveal that at ambient conditions Fe4O5 is a narrow-gap insulator characterized by the original Verwey-type CO. Under pressure Fe4O5 undergoes a series of electronic and magnetic-state transitions with an unusual compressional behavior above ∼50 GPa. A site-dependent collapse of local magnetic moments is followed by the site-selective insulator-to-metal transition at ∼84 GPa, occurring at the octahedral Fe sites. This phase transition is accompanied by a 2+ to 3+ valence change of the prismatic Fe ions and collapse of CO. We provide a microscopic explanation of the complex charge ordering in Fe4O5 which "unifies" it with the behavior of two archetypal examples of charge- or bond-ordered materials, magnetite and rare-earth nickelates (RNiO3). We find that at low temperatures the Verwey-type CO competes with the "trimeron"/"dimeron" charge ordered states, allowing for pressure/temperature tuning of charge ordering. Summing up the available data, we present the pressure-temperature phase diagram of Fe4O5.
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Affiliation(s)
- Samar Layek
- School
of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv, Israel
- Department
of Physics, School of Engineering, University
of Petroleum and Energy Studies (UPES), Dehradun, Uttarakhand 248007, India
| | - Eran Greenberg
- Center
for Advanced Radiation Sources, University
of Chicago, 5640 South Ellis Avenue, 60637 Chicago, United States
- Applied
Physics Division, Soreq NRC, Yavne, 81800, Israel
| | - Stella Chariton
- Center
for Advanced Radiation Sources, University
of Chicago, 5640 South Ellis Avenue, 60637 Chicago, United States
| | - Maxim Bykov
- Institute
of Inorganic Chemistry, University of Cologne, Greinstrasse 6, 50939 Cologne, Germany
| | - Elena Bykova
- Earth
and
Planets Laboratory, Carnegie Institution
for Science, Washington, District of Columbia 20015, United States
- Bayerisches
Geoinstitut, Universität Bayreuth, Universitätsstrasse 30, D-95447 Bayreuth, Germany
| | - Dmytro M. Trots
- Bayerisches
Geoinstitut, Universität Bayreuth, Universitätsstrasse 30, D-95447 Bayreuth, Germany
| | - Alexander V. Kurnosov
- Bayerisches
Geoinstitut, Universität Bayreuth, Universitätsstrasse 30, D-95447 Bayreuth, Germany
| | - Irina Chuvashova
- Harvard
Physics, Jefferson Physical
Lab, 17 Oxford Street, Cambridge, Massachusetts 02138, United States
- Department
of Chemistry and Biochemistry, Florida International
University, 11200 SW
Eighth Street, CP 234, Miami, Florida 33199, United
States
| | - Sergey V. Ovsyannikov
- Bayerisches
Geoinstitut, Universität Bayreuth, Universitätsstrasse 30, D-95447 Bayreuth, Germany
| | - Ivan Leonov
- M. N. Miheev
Institute of Metal Physics, Russian Academy
of Sciences, 620108 Yekaterinburg, Russia
- Ural
Federal University, 620002 Yekaterinburg, Russia
- Skolkovo
Institute of Science and Technology, 143026 Moscow, Russia
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7
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Sun L, Deng P, Zhao J, Gong HR, Liang CP. Cohesive properties of PbBi/Fe 3O 4 and PbBi/(Fe,Cr) 3O 4 interfaces. Phys Chem Chem Phys 2022; 24:6732-6741. [PMID: 35234768 DOI: 10.1039/d1cp05953j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
First principles calculations reveal that the effects of PbBi on the cohesive properties of Fe3O4 and (Fe,Cr)3O4: PbBi can reduce the cohesive strength of the oxides, and the contents of O and Cr on the O-terminated oxide side play a significant role in the cohesive properties of the PbBi/Fe3O4 and PbBi/(Fe,Cr)3O4 interfaces. Specifically, the performance of oxidation decreases more significantly under the conditions of insufficient oxygen, and a high ratio of Cr of the subsurface of oxides can lead to the reduction of the cohesive properties of O-terminated interfaces. Calculations also show that the Pb-O-terminated interfaces are energetically favorable and are more stable than the Bi-O-terminated surfaces due to the strong bond of Pb-O, while the Bi-Cr and Bi-Fe interfaces are more stable than the Pb-Cr and Pb-Fe interfaces. Moreover, it is found that the stability and cohesion of the PbBi/Fe3O4 and PbBi/(Fe,Cr)3O4 interfaces will decrease when the oxygen concentration is insufficient or the degree of wetting of PbBi of oxides is low, and the PbBi/Fe3O4 interface is more sensitive to these conditions. The bond-dissociation energies and electronic structures provide a deep understanding of various interface properties, and the obtained results are in good agreement with experimental measurements in the literature.
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Affiliation(s)
- L Sun
- State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, China.
| | - P Deng
- Reactor Engineering Research Sub-institute, Nuclear Power Institute of China, Chengdu 610213, China
| | - J Zhao
- State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, China.
| | - H R Gong
- State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, China.
| | - C P Liang
- State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, China.
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8
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Pervishko AA, Yudin D, Kumar Gudelli V, Delin A, Eriksson O, Guo GY. Localized surface electromagnetic waves in CrI 3-based magnetophotonic structures. OPTICS EXPRESS 2020; 28:29155-29165. [PMID: 33114820 DOI: 10.1364/oe.394113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 08/05/2020] [Indexed: 06/11/2023]
Abstract
Resulting from strong magnetic anisotropy two-dimensional ferromagnetism was recently shown to be stabilized in chromium triiodide, CrI3, in the monolayer limit. While its properties remain largely unexplored, it provides a unique material-specific platform to unveil its electromagnetic properties associated with coupling of modes. Indeed, trigonal symmetry in the presence of out-of-plane magnetization results in a non-trivial structure of the conductivity tensor, including the off-diagonal terms. In this paper, we study the surface electromagnetic waves localized in a CrI3-based structure using the results of ab initio calculations for the CrI3 conductivity tensor. In particular, we provide an estimate for the critical angle corresponding to the surface plasmon polariton generation in the Kretschmann-Raether configuration by a detailed investigation of reflectance spectrum as well as the magnetic field distribution for different CrI3 layer thicknesses. We also study the bilayer structure formed by two CrI3 layers separated by a SiO2 spacer and show that the surface plasmon resonance can be achieved at the interface between CrI3 and air depending on the spacer thickness.
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9
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Shen X, Wang Z, Gao X, Zhao Y. Density Functional Theory-Based Method to Predict the Activities of Nanomaterials as Peroxidase Mimics. ACS Catal 2020. [DOI: 10.1021/acscatal.0c03426] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Xiaomei Shen
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China
| | - Zhenzhen Wang
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Xingfa Gao
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China
| | - Yuliang Zhao
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
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10
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Heat capacity signature of frustrated trimerons in magnetite. Sci Rep 2020; 10:10909. [PMID: 32616822 PMCID: PMC7331697 DOI: 10.1038/s41598-020-67955-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 05/28/2020] [Indexed: 11/08/2022] Open
Abstract
Recently it has been proposed that the long-range electronic order formed by trimerons in magnetite should be frustrated due to the great degeneracy of arrangements linking trimerons. This result has important consequences as charge ordering from the condensed minority band electrons leads to a complex 3D antiferro orbital order pattern. Further more, the corner sharing tetrahedra structure of spinel B-sites supports frustration for antiferromagnetic alignments. Therefore frustration due to competing interactions will itself induce disorder and very likely frustration in the spin orientations. Here we present very low temperature specific heat data that show two deviations to the magnons and phonons contributions, that we analyze in terms of Schottky-type anomalies. The first one is associated with the thermal activation across both ferroelastic twin and ferromagnetic anti-phase domains. The second Schottky-type anomaly displays an inverse (1/H) field dependence which is a direct indication of the disordered glassy network with macroscopically degenerated singular ground states.
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11
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Huang HL, Jeng HT. Orbital ordering and magnetism in layered Perovskite Ruthenate Sr 2RuO 4. Sci Rep 2020; 10:7089. [PMID: 32341446 PMCID: PMC7184627 DOI: 10.1038/s41598-020-63415-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 03/31/2020] [Indexed: 11/17/2022] Open
Abstract
Local density approximation plus on-site Coulomb interaction U electronic structure calculations reveal that layered perovskite oxide Sr2RuO4 exhibits the ferromagnetic (FM) half-metallic ground state, which is nearly degenerate with the antiferromagnetic (AFM) phase with a slightly higher total energy. The nearly degenerate FM/AFM total energies provide a reasonable explanation for the experimentally observed spin-fluctuation. In addition, a dumbbell-shape 4d − t2g recombined dxz − dyz orbital ordering on the Ru sublattice is obtained owing to the on-site Coulomb interaction U associated with the elongated RuO6 octahedron local structure. The discovered orbital ordering is robust against the spin-orbit interaction as well as the surface terminations. Our findings unravel the on-site Coulomb correlation as the driving force of the Ru-4d orbital ordering as well as the inherent magnetic degeneracy.
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Affiliation(s)
- Hung-Lung Huang
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan. .,Physics Division, National Center for Theoretical Sciences, Hsinchu, 30013, Taiwan. .,Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan.
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12
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Yuk SF, Collinge G, Nguyen MT, Lee MS, Glezakou VA, Rousseau R. Selective acetylene hydrogenation over single metal atoms supported on Fe3O4(001): A first-principle study. J Chem Phys 2020; 152:154703. [DOI: 10.1063/1.5142748] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Simuck F. Yuk
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Greg Collinge
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Manh-Thuong Nguyen
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Mal-Soon Lee
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Vassiliki-Alexandra Glezakou
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Roger Rousseau
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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13
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Liu H, Di Valentin C. Shaping Magnetite Nanoparticles from First Principles. PHYSICAL REVIEW LETTERS 2019; 123:186101. [PMID: 31763909 DOI: 10.1103/physrevlett.123.186101] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 09/12/2019] [Indexed: 06/10/2023]
Abstract
Iron oxide magnetic nanoparticles (NPs) are stimuli-responsive materials at the forefront of nanomedicine. Their realistic finite temperature simulations are a formidable challenge for first-principles methods. Here, we use density functional tight binding to open up the required time and length scales and obtain global minimum structures of Fe_{3}O_{4} NPs of realistic size (1400 atoms, 2.5 nm) and of different shapes, which we then refine with hybrid density functional theory methods to accomplish proper electronic and magnetic properties, which have never been accurately described in simulations. On this basis, we develop a general empirical formula and prove its predictive power for the evaluation of the total magnetic moment of Fe_{3}O_{4} NPs. By converting the total magnetic moment into the macroscopic saturation magnetization, we rationalize the experimentally observed dependence with shape. We also reveal interesting reconstruction mechanisms and unexpected patterns of charge ordering.
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Affiliation(s)
- Hongsheng Liu
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via Roberto Cozzi 55, I-20125 Milano, Italy
| | - Cristiana Di Valentin
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via Roberto Cozzi 55, I-20125 Milano, Italy
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14
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Doudin N, Yuk SF, Marcinkowski MD, Nguyen MT, Liu JC, Wang Y, Novotny Z, Kay BD, Li J, Glezakou VA, Parkinson G, Rousseau R, Dohnálek Z. Understanding Heterolytic H2 Cleavage and Water-Assisted Hydrogen Spillover on Fe3O4(001)-Supported Single Palladium Atoms. ACS Catal 2019. [DOI: 10.1021/acscatal.9b01425] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Nassar Doudin
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Simuck F. Yuk
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Matthew D. Marcinkowski
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Manh-Thuong Nguyen
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Jin-Cheng Liu
- Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Yang Wang
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Zbynek Novotny
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Bruce D. Kay
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Jun Li
- Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Vassiliki-Alexandra Glezakou
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Gareth Parkinson
- Institute of Applied Physics, Vienna University of Technology, Vienna 1040, Austria
| | - Roger Rousseau
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Zdenek Dohnálek
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99163, United States
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15
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Liu X, Mi W. Electronic transport properties and magnetoresistance in the Fe 3O 4/SiO 2/p-Si heterostructure with an in-plane current geometry. Phys Chem Chem Phys 2019; 21:7518-7523. [PMID: 30895978 DOI: 10.1039/c9cp00033j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In traditional electronic devices, the electronic charge is manipulated to realize different functions. The fascinating control of electronic spin in conventional semiconductors increases the probability of occurrence of spin-dependent transport properties. Herein, the injection of electronic spin into a Si wafer with in-plane geometry was achieved by Fe3O4, which acted as a spin injector. At high temperatures, the resistivity of Fe3O4 is far less than that of a p-Si wafer. Moreover, above 190 K, the current-voltage (I-V) characteristic and magnetoresistance (MR) of the proposed heterostructure are dominated by the intrinsic properties of a polycrystalline Fe3O4 film, and the in-plane current flows in the Fe3O4 layer. Due to the increased resistivity of Fe3O4 at low temperatures, the in-plane conductive channel gradually switches from Fe3O4 to Si. The spin injection from Fe3O4 results in a spin-polarized space charge region in p-Si. The heterostructure shows an MR of up to -76.1% at 90 K due to the spin-dependent transport of electrons in p-Si. With a further decrease in temperature, the I-V characteristic of the heterostructure shows negative differential resistance below 80 K due to band bending at the Fe3O4/SiO2/p-Si interface.
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Affiliation(s)
- Xiang Liu
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, School of Science, Tianjin University, Tianjin 300354, China.
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16
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Nie X, Meng L, Wang H, Chen Y, Guo X, Song C. DFT insight into the effect of potassium on the adsorption, activation and dissociation of CO 2 over Fe-based catalysts. Phys Chem Chem Phys 2018; 20:14694-14707. [PMID: 29774346 DOI: 10.1039/c8cp02218f] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Catalytic conversion of CO2 including hydrogenation has attracted great attention as a method for chemical fixation of CO2 in combination with other techniques such as CO2 capture and storage. Potassium is a well-known promotor for many industrial catalytic processes such as in Fischer-Tropsch synthesis. In this work, we performed density functional theory (DFT) calculations to investigate the effect of potassium on the adsorption, activation, and dissociation of CO2 over Fe(100), Fe5C2(510) and Fe3O4(111) surfaces. The function of K was analyzed in terms of electronic interactions between co-adsorbed CO2 and K-surfaces which showed conspicuous promotion in the presence of K of the adsorption and activation of CO2. The adsorption strength of CO2 on these surfaces ranks as oct2-Fe3O4(111) > Fe(100) > Fe5C2(510). Generally, we observed a direct proportional correlation between the adsorption strength and the charges on the adsorbates. Adding K on the catalyst surface also reduces the kinetic barrier for CO2 dissociation. CO2 dissociation is more facile to occur on Fe(100) and Fe5C2(510) in the presence of K whereas the Fe3O4(111) surfaces impede CO2 dissociation regardless of the existence of K. Instead, a stable CO3- species is formed upon CO2 adsorption on Fe3O4(111) which will be directly hydrogenated when sufficient H* are available on the surface. Our results highlight the origin of the promotion effect of potassium and provide insight for the future design of K-promoted Fe-based catalysts for CO2 hydrogenation.
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Affiliation(s)
- Xiaowa Nie
- School of Chemical Engineering, PSU-DUT Joint Center for Energy Research, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, P. R. China.
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17
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Kim T, Lim S, Hong J, Kwon SG, Okamoto J, Chen ZY, Jeong J, Kang S, Leiner JC, Lim JT, Kim CS, Huang DJ, Hyeon T, Lee S, Park JG. Giant thermal hysteresis in Verwey transition of single domain Fe 3O 4 nanoparticles. Sci Rep 2018; 8:5092. [PMID: 29572467 PMCID: PMC5865112 DOI: 10.1038/s41598-018-23456-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 03/13/2018] [Indexed: 11/10/2022] Open
Abstract
Most interesting phenomena of condensed matter physics originate from interactions among different degrees of freedom, making it a very intriguing yet challenging question how certain ground states emerge from only a limited number of atoms in assembly. This is especially the case for strongly correlated electron systems with overwhelming complexity. The Verwey transition of Fe3O4 is a classic example of this category, of which the origin is still elusive 80 years after the first report. Here we report, for the first time, that the Verwey transition of Fe3O4 nanoparticles exhibits size-dependent thermal hysteresis in magnetization, 57Fe NMR, and XRD measurements. The hysteresis width passes a maximum of 11 K when the size is 120 nm while dropping to only 1 K for the bulk sample. This behavior is very similar to that of magnetic coercivity and the critical sizes of the hysteresis and the magnetic single domain are identical. We interpret it as a manifestation of charge ordering and spin ordering correlation in a single domain. This work paves a new way of undertaking researches in the vibrant field of strongly correlated electron physics combined with nanoscience.
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Affiliation(s)
- Taehun Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Korea.,Department of Physics & Astronomy, Seoul National University, Seoul, 08826, Korea
| | - Sumin Lim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Korea
| | - Jaeyoung Hong
- Center for Nanoparticle Research, Institute for Basic Science, Seoul, 08826, Korea.,School of Chemical and Biological Engineering, Seoul National University, Seoul, 08826, Korea
| | - Soon Gu Kwon
- Center for Nanoparticle Research, Institute for Basic Science, Seoul, 08826, Korea.,School of Chemical and Biological Engineering, Seoul National University, Seoul, 08826, Korea
| | - Jun Okamoto
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Zhi Ying Chen
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Jaehong Jeong
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Korea.,Department of Physics & Astronomy, Seoul National University, Seoul, 08826, Korea
| | - Soonmin Kang
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Korea.,Department of Physics & Astronomy, Seoul National University, Seoul, 08826, Korea
| | - Jonathan C Leiner
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Korea.,Department of Physics & Astronomy, Seoul National University, Seoul, 08826, Korea
| | - Jung Tae Lim
- Department of Physics, Kookmin University, Seoul, 02703, Korea
| | - Chul Sung Kim
- Department of Physics, Kookmin University, Seoul, 02703, Korea
| | - Di Jing Huang
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan.,Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Taeghwan Hyeon
- Center for Nanoparticle Research, Institute for Basic Science, Seoul, 08826, Korea.,School of Chemical and Biological Engineering, Seoul National University, Seoul, 08826, Korea
| | - Soonchil Lee
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Korea
| | - Je-Geun Park
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Korea. .,Department of Physics & Astronomy, Seoul National University, Seoul, 08826, Korea.
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18
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Adler P, Jeglič P, Reehuis M, Geiß M, Merz P, Knaflič T, Komelj M, Hoser A, Sans A, Janek J, Arčon D, Jansen M, Felser C. Verwey-type charge ordering transition in an open-shell p-electron compound. SCIENCE ADVANCES 2018; 4:eaap7581. [PMID: 29372183 PMCID: PMC5775027 DOI: 10.1126/sciadv.aap7581] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 12/11/2017] [Indexed: 06/07/2023]
Abstract
The Verwey transition in Fe3O4, a complex structural phase transition concomitant with a jump in electrical conductivity by two orders of magnitude, has been a benchmark for charge ordering (CO) phenomena in mixed-valence transition metal materials. CO is of central importance, because it frequently competes with functional properties such as superconductivity or metallic ferromagnetism. However, the CO state in Fe3O4 turned out to be complex, and the mechanism of the Verwey transition remains controversial. We demonstrate an archetypical Verwey-type transition in an open p-shell anionic mixed-valence compound using complementary diffraction and spectroscopic techniques. In Cs4O6, a phase change from a cubic structure with a single crystallographic site for the molecular O2x- building units to a tetragonal structure with ordered superoxide O2- and peroxide O22- entities is accompanied by a drastic drop in electronic conductivity and molecular charge fluctuation rates. The simple CO pattern of molecular units and the lack of magnetic order suggest Cs4O6 as a model system for disentangling the complex interplay of charge, lattice, orbital, and spin degrees of freedom in Verwey-type CO processes.
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Affiliation(s)
- Peter Adler
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Peter Jeglič
- Jožef Stefan Institute, Jamova c. 39, 1000 Ljubljana, Slovenia
| | - Manfred Reehuis
- Helmholtz-Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany
| | - Matthias Geiß
- Institute of Physical Chemistry and Center for Materials Research, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Patrick Merz
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Tilen Knaflič
- Jožef Stefan Institute, Jamova c. 39, 1000 Ljubljana, Slovenia
| | - Matej Komelj
- Jožef Stefan Institute, Jamova c. 39, 1000 Ljubljana, Slovenia
| | - Andreas Hoser
- Helmholtz-Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany
| | - Annette Sans
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Jürgen Janek
- Institute of Physical Chemistry and Center for Materials Research, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Denis Arčon
- Jožef Stefan Institute, Jamova c. 39, 1000 Ljubljana, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska c. 19, 1000 Ljubljana, Slovenia
| | - Martin Jansen
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
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19
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Zaki E, Mirabella F, Ivars-Barceló F, Seifert J, Carey S, Shaikhutdinov S, Freund HJ, Li X, Paier J, Sauer J. Water adsorption on the Fe3O4(111) surface: dissociation and network formation. Phys Chem Chem Phys 2018; 20:15764-15774. [DOI: 10.1039/c8cp02333f] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Water adsorption on Fe3O4(111) is studied in detail using infrared spectroscopy, temperature programmed desorption, micro-calorimetry and density functional theory.
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Affiliation(s)
- Eman Zaki
- Abteilung Chemische Physik
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- 14195 Berlin
- Germany
| | - Francesca Mirabella
- Abteilung Chemische Physik
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- 14195 Berlin
- Germany
| | - Francisco Ivars-Barceló
- Abteilung Chemische Physik
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- 14195 Berlin
- Germany
| | - Jan Seifert
- Abteilung Chemische Physik
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- 14195 Berlin
- Germany
| | - Spencer Carey
- Abteilung Chemische Physik
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- 14195 Berlin
- Germany
| | - Shamil Shaikhutdinov
- Abteilung Chemische Physik
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- 14195 Berlin
- Germany
| | - Hans-Joachim Freund
- Abteilung Chemische Physik
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- 14195 Berlin
- Germany
| | - Xiaoke Li
- Institut für Chemie
- Humboldt-Universität zu Berlin
- 10099 Berlin
- Germany
| | - Joachim Paier
- Institut für Chemie
- Humboldt-Universität zu Berlin
- 10099 Berlin
- Germany
| | - Joachim Sauer
- Institut für Chemie
- Humboldt-Universität zu Berlin
- 10099 Berlin
- Germany
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20
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Hu Y, Ji C, Wang X, Huo J, Liu Q, Song Y. The structural, magnetic and optical properties of TM n@(ZnO) 42 (TM = Fe, Co and Ni) hetero-nanostructure. Sci Rep 2017; 7:16485. [PMID: 29184077 PMCID: PMC5705660 DOI: 10.1038/s41598-017-16532-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 11/13/2017] [Indexed: 12/05/2022] Open
Abstract
The magnetic transition-metal (TM) @ oxide nanoparticles have been of great interest due to their wide range of applications, from medical sensors in magnetic resonance imaging to photo-catalysis. Although several studies on small clusters of TM@oxide have been reported, the understanding of the physical electronic properties of TMn@(ZnO)42 is far from sufficient. In this work, the electronic, magnetic and optical properties of TMn@(ZnO)42 (TM = Fe, Co and Ni) hetero-nanostructure are investigated using the density functional theory (DFT). It has been found that the core-shell nanostructure Fe13@(ZnO)42, Co15@(ZnO)42 and Ni15@(ZnO)42 are the most stable structures. Moreover, it is also predicted that the variation of the magnetic moment and magnetism of Fe, Co and Ni in TMn@ZnO42 hetero-nanostructure mainly stems from effective hybridization between core TM-3d orbitals and shell O-2p orbitals, and a magnetic moment inversion for Fe15@(ZnO)42 is investigated. Finally, optical properties studied by calculations show a red shift phenomenon in the absorption spectrum compared with the case of (ZnO)48.
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Affiliation(s)
- Yaowen Hu
- Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Chuting Ji
- Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Xiaoxu Wang
- Department of Physics, University of Science and Technology Beijing, Beijing, 100083, China.,Department of Cloud Platform, Beijing Computing Center, Beijing, 100094, China
| | - Jinrong Huo
- Department of Physics, University of Science and Technology Beijing, Beijing, 100083, China
| | - Qing Liu
- Department of Physics, University of Science and Technology Beijing, Beijing, 100083, China
| | - Yipu Song
- Center for Quantum Information, IIIS, Tsinghua University, Beijing, 100084, China.
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21
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Liu H, Di Valentin C. Band Gap in Magnetite above Verwey Temperature Induced by Symmetry Breaking. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2017; 121:25736-25742. [PMID: 29201266 PMCID: PMC5706067 DOI: 10.1021/acs.jpcc.7b09387] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/24/2017] [Indexed: 05/12/2023]
Abstract
Magnetite exhibits a famous phase transition, called Verwey transition, at the critical temperature TV of about 120 K. Although numerous efforts have been devoted to the understanding of this interesting transition, up to now, it is still under debate whether a charge ordering and a band gap exist in magnetite above TV. Here, we systematically investigate the charge ordering and the electronic properties of magnetite in its cubic phase using different methods based on density functional theory: DFT+U and hybrid functionals. Our results show that, upon releasing the symmetry constraint on the density but not on the geometry, charge disproportionation (Fe2+/Fe3+) is observed, resulting in a band gap of around 0.2 eV at the Fermi level. This implies that the Verwey transition is probably a semiconductor-to-semiconductor transition and that the conductivity mechanism above TV is small polaron hopping.
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22
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Yeo S, Choi H, Kim CS, Lee GT, Seo JH, Cha HJ, Park JC. Survival of Verwey transition in gadolinium-doped ultrasmall magnetite nanoparticles. NANOSCALE 2017; 9:13976-13982. [PMID: 28920122 DOI: 10.1039/c7nr03684a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We have demonstrated that the Verwey transition, which is highly sensitive to impurities, survives in anisotropic Gd-doped magnetite nanoparticles. Transmission electron microscopy analysis shows that the nanoparticles are uniformly distributed. X-ray photoelectron spectroscopy and EDS mapping analysis confirm Gd-doping on the nanoparticles. The Verwey transition of the Gd-doped magnetite nanoparticles is robust and the temperature dependence of the magnetic moment (zero field cooling and field cooling) shows the same behaviour as that of the Verwey transition in bulk magnetite, at a lower transition temperature (∼110 K). In addition, irregularly shaped nanoparticles do not show the Verwey transition whereas square-shaped nanoparticles show the transition. Mössbauer spectral analysis shows that the slope of the magnetic hyperfine field and the electric quadrupole splitting change at the same temperature, meaning that the Verwey transition occurs at ∼110 K. These results would provide new insights into understanding the Verwey transition in nano-sized materials.
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Affiliation(s)
- Sunmog Yeo
- Korea Multi-purpose Accelerator Complex, Korea Atomic Energy Research Institute, Gyeongju, 305-353, Korea
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23
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Huang HY, Chen ZY, Wang RP, de Groot FMF, Wu WB, Okamoto J, Chainani A, Singh A, Li ZY, Zhou JS, Jeng HT, Guo GY, Park JG, Tjeng LH, Chen CT, Huang DJ. Jahn-Teller distortion driven magnetic polarons in magnetite. Nat Commun 2017; 8:15929. [PMID: 28660878 PMCID: PMC5493765 DOI: 10.1038/ncomms15929] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Accepted: 05/12/2017] [Indexed: 11/20/2022] Open
Abstract
The first known magnetic mineral, magnetite, has unusual properties, which have fascinated mankind for centuries; it undergoes the Verwey transition around 120 K with an abrupt change in structure and electrical conductivity. The mechanism of the Verwey transition, however, remains contentious. Here we use resonant inelastic X-ray scattering over a wide temperature range across the Verwey transition to identify and separate out the magnetic excitations derived from nominal Fe2+ and Fe3+ states. Comparison of the experimental results with crystal-field multiplet calculations shows that the spin–orbital dd excitons of the Fe2+ sites arise from a tetragonal Jahn-Teller active polaronic distortion of the Fe2+O6 octahedra. These low-energy excitations, which get weakened for temperatures above 350 K but persist at least up to 550 K, are distinct from optical excitations and are best explained as magnetic polarons. The Verwey transition of magnetite is complex due to the coexistence of strong correlations and electron-phonon coupling. Here, the authors use resonant inelastic X-ray scattering to show evidence for magnetic polarons in magnetite and provide insight into the nature of the transition.
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Affiliation(s)
- H Y Huang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.,Program of Science and Technology of Synchrotron Light Source, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Z Y Chen
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - R-P Wang
- Inorganic Chemistry and Catalysis, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - F M F de Groot
- Inorganic Chemistry and Catalysis, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - W B Wu
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - J Okamoto
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - A Chainani
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - A Singh
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Z-Y Li
- Department of Mechanical Engineering, Texas Material Institute, University of Texas at Austin, Austin, Texas 78712, USA
| | - J-S Zhou
- Department of Mechanical Engineering, Texas Material Institute, University of Texas at Austin, Austin, Texas 78712, USA
| | - H-T Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - G Y Guo
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan.,Division of Physics, National Center for Theoretical Sciences, Hsinchu 30013, Taiwan
| | - Je-Geun Park
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea.,Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
| | - L H Tjeng
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzerstr. 40, 01187 Dresden, Germany
| | - C T Chen
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - D J Huang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.,Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
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24
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Li X, Paier J, Sauer J, Mirabella F, Zaki E, Ivars-Barceló F, Shaikhutdinov S, Freund HJ. Surface Termination of Fe 3O 4(111) Films Studied by CO Adsorption Revisited. J Phys Chem B 2017. [PMID: 28621937 DOI: 10.1021/acs.jpcb.7b04228] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Although the (111) surface of Fe3O4 (magnetite) has been investigated for more than 20 years, substantial controversy remains in the literature regarding the surface termination proposed based on structural and adsorption studies. The present article provides density functional theory results that allow to rationalize experimental results of infrared reflection-absorption spectroscopy and temperature-programmed desorption studies on CO adsorption, thus leading to a unified picture in which the Fe3O4(111) surface is terminated by a 1/4 monolayer of tetrahedrally coordinated Fe3+ ions on top of a close-packed oxygen layer as previously determined by low energy electron diffraction. However, surface defects play a crucial role in adsorption properties and may dominate chemical reactions on Fe3O4(111) when exposed to the ambient.
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Affiliation(s)
- X Li
- Institut für Chemie, Humboldt-Universität zu Berlin , 10099 Berlin, Germany
| | - J Paier
- Institut für Chemie, Humboldt-Universität zu Berlin , 10099 Berlin, Germany
| | - J Sauer
- Institut für Chemie, Humboldt-Universität zu Berlin , 10099 Berlin, Germany
| | - F Mirabella
- Fritz-Haber-Institute, Max Planck Society , Faradayweg 4-6, 14195 Berlin, Germany
| | - E Zaki
- Fritz-Haber-Institute, Max Planck Society , Faradayweg 4-6, 14195 Berlin, Germany
| | - F Ivars-Barceló
- Fritz-Haber-Institute, Max Planck Society , Faradayweg 4-6, 14195 Berlin, Germany
| | - S Shaikhutdinov
- Fritz-Haber-Institute, Max Planck Society , Faradayweg 4-6, 14195 Berlin, Germany
| | - H-J Freund
- Fritz-Haber-Institute, Max Planck Society , Faradayweg 4-6, 14195 Berlin, Germany
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25
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Liu X, Yin L, Mi W. Biaxial strain effect induced electronic structure alternation and trimeron recombination in Fe 3O 4. Sci Rep 2017; 7:43403. [PMID: 28230194 PMCID: PMC5322496 DOI: 10.1038/srep43403] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 01/20/2017] [Indexed: 12/03/2022] Open
Abstract
The Verwey transition in Fe3O4 is the first metal-insulator transition caused by charge ordering. However, the physical mechanism and influence factors of Verwey transition are still debated. Herewith, the strain effects on the electronic structure of low-temperature phase (LTP) Fe3O4 with P2/c and Cc symmetries are investigated by first-principles calculations. LTP Fe3O4 with each space group has a critical strain. With P2/c, Fe3O4 is sensitive to the compressive strain, but it is sensitive to tensile strain for Cc. In the critical region, the band gap of LTP Fe3O4 with both two symmetries linearly increases with strain. When strain exceeds the critical value, DOS of spin-down t2g electron at Fe(B4) with P2/c and Fe(B42) with Cc changes between dx2-y2 and dxz + dyz. The trimerons appear in Cc can be affected by strain. With a compressive strain, the correlation of trimeron along x and y axes is strengthened, but broken along the face diagonal of FeB4O4, which is opposite at the tensile strains. The results suggest that the electronic structure of Fe3O4 is tunable by strain. The narrower or wider band gap implies a lower or higher transition temperature than its bulk without strains, which also gives a glimpse of the origin of charge-orbital ordering in Fe3O4.
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Affiliation(s)
- Xiang Liu
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, Faculty of Science, Tianjin University, Tianjin 300072, China
| | - Li Yin
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, Faculty of Science, Tianjin University, Tianjin 300072, China
| | - Wenbo Mi
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, Faculty of Science, Tianjin University, Tianjin 300072, China
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26
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Meng Y, Liu XW, Huo CF, Guo WP, Cao DB, Peng Q, Dearden A, Gonze X, Yang Y, Wang J, Jiao H, Li Y, Wen XD. When Density Functional Approximations Meet Iron Oxides. J Chem Theory Comput 2016; 12:5132-5144. [DOI: 10.1021/acs.jctc.6b00640] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yu Meng
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China
- National
Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd., Huairou District, Beijing 101400, P. R. China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, P. R. China
| | - Xing-Wu Liu
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China
- National
Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd., Huairou District, Beijing 101400, P. R. China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, P. R. China
| | - Chun-Fang Huo
- National
Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd., Huairou District, Beijing 101400, P. R. China
| | - Wen-Ping Guo
- National
Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd., Huairou District, Beijing 101400, P. R. China
| | - Dong-Bo Cao
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China
- National
Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd., Huairou District, Beijing 101400, P. R. China
| | - Qing Peng
- Department
of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Albert Dearden
- Department
of Physics, Berea College, Berea, Kentucky 40403, United States
| | - Xavier Gonze
- Institute
of Condensed Matter and Nanosciences, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Yong Yang
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China
- National
Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd., Huairou District, Beijing 101400, P. R. China
| | - Jianguo Wang
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China
| | - Haijun Jiao
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China
- Leibniz-Institut
für Katalyse e.V., Universität Rostock, Albert-Einstein
Strasse 29a, 18059 Rostock, Germany
| | - Yongwang Li
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China
- National
Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd., Huairou District, Beijing 101400, P. R. China
| | - Xiao-Dong Wen
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China
- National
Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd., Huairou District, Beijing 101400, P. R. China
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27
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Paier J. Hybrid Density Functionals Applied to Complex Solid Catalysts: Successes, Limitations, and Prospects. Catal Letters 2016. [DOI: 10.1007/s10562-016-1735-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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28
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Li D, Qu B, He HY, Zhang YG, Xu Y, Pan BC, Zhou R. The influence of liquid Pb-Bi on the anti-corrosion behavior of Fe3O4: a first-principles study. Phys Chem Chem Phys 2016; 18:7789-96. [PMID: 26912208 DOI: 10.1039/c5cp07564e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
In this work, the influence of Pb and Bi atoms on the anti-corrosion behavior of the oxide film (Fe3O4) formed on steel surface is investigated based on first-principles calculations. Through calculations of the formation energies, we find that Pb and Bi atoms can promote the formation of point defects, such as interstitial atoms and vacancies in Fe3O4. Besides, the effects of the concentration of Pb (or Bi) and pressure on the formation of these defects are also studied. Our results depict that a high density of Pb (or Bi) and compression pressure can promote the formation of defects in Fe3O4 significantly. Furthermore, the energy barriers for Pb and Bi atom migration in Fe3O4 are also estimated using the climbing image nudge elastic band (CI-NEB) method, which implies that Pb and Bi can diffuse more easily in Fe3O4 compared to Fe. Our results reveal the underlying mechanism of how Pb and Bi influence the anti-corrosion ability of oxide films in an accelerate driven system (ADS). It is instructive for improving the corrosion resistance of the oxide films in the ADS.
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Affiliation(s)
- Dongdong Li
- Laboratory of Amorphous Materials, School of Materials Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China.
| | - Bingyan Qu
- Laboratory of Amorphous Materials, School of Materials Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China.
| | - H Y He
- Hefei National Laboratory for Physical Sciences at Microscale, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
| | - Y G Zhang
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031, P. R. China
| | - Yichun Xu
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031, P. R. China
| | - B C Pan
- Hefei National Laboratory for Physical Sciences at Microscale, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
| | - Rulong Zhou
- Laboratory of Amorphous Materials, School of Materials Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China.
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29
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Reversed ageing of Fe3O4 nanoparticles by hydrogen plasma. Sci Rep 2016; 6:20897. [PMID: 26902789 PMCID: PMC4763261 DOI: 10.1038/srep20897] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 01/12/2016] [Indexed: 11/23/2022] Open
Abstract
Magnetite (Fe3O4) nanoparticles suffer from severe ageing effects when exposed to air even when they are dispersed in a solvent limiting their applications. In this work, we show that this ageing can be fully reversed by a hydrogen plasma treatment. By x-ray absorption spectroscopy and its associated magnetic circular dichroism, the electronic structure and magnetic properties were studied before and after the plasma treatment and compared to results of freshly prepared magnetite nanoparticles. While aged magnetite nanoparticles exhibit a more γ-Fe2O3 like behaviour, the hydrogen plasma yields pure Fe3O4 nanoparticles. Monitoring the temperature dependence of the intra-atomic spin dipole contribution to the dichroic spectra gives evidence that the structural, electronic and magnetic properties of plasma treated magnetite nanoparticles can outperform the ones of the freshly prepared batch.
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30
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Wu M, Tse JS, Pan Y. Electronic structures of greigite (Fe3S4): A hybrid functional study and prediction for a Verwey transition. Sci Rep 2016; 6:21637. [PMID: 26869147 PMCID: PMC4751502 DOI: 10.1038/srep21637] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 01/27/2016] [Indexed: 11/30/2022] Open
Abstract
Greigite (Fe3S4) is a ferrimagnetic mineral with vital functions in both the bio-geochemical cycle and novel technological applications. However, the ground state electronic structure of this material has not been fully characterized by either experiment or theory. In the present study, ab initio calculations using the hybrid functional method have been performed to investigate the electronic structure and magnetic properties. It is found that the cubic structure observed under ambient temperature is a half metal and is metastable. A more stable monoclinic structure slightly distorted from the cubic form is found. The structural distortion is induced by charge ordering and associated with a metal-to-insulator transition, resulting in a semiconductive ground state with a bandgap of ~0.8 eV and a magnetic moment of 4 μB per formula unit. The results predict, similar to the magnetite (Fe3O4), a Verwey transition may exist in greigite, although it has not yet been observed experimentally.
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Affiliation(s)
- Min Wu
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou, 310014, China.,Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 Canada.,Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 Canada
| | - John S Tse
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 Canada
| | - Yuanming Pan
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 Canada
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31
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Taguchi M, Chainani A, Ueda S, Matsunami M, Ishida Y, Eguchi R, Tsuda S, Takata Y, Yabashi M, Tamasaku K, Nishino Y, Ishikawa T, Daimon H, Todo S, Tanaka H, Oura M, Senba Y, Ohashi H, Shin S. Temperature Dependence of Magnetically Active Charge Excitations in Magnetite across the Verwey Transition. PHYSICAL REVIEW LETTERS 2015; 115:256405. [PMID: 26722935 DOI: 10.1103/physrevlett.115.256405] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Indexed: 05/12/2023]
Abstract
We study the electronic structure of bulk single crystals and epitaxial films of Fe_{3}O_{4}. Fe 2p core level spectra show clear differences between hard x-ray (HAX) and soft x-ray photoemission spectroscopy (PES). The bulk-sensitive spectra exhibit temperature (T) dependence across the Verwey transition, which is missing in the surface-sensitive spectra. By using an extended impurity Anderson full-multiplet model-and in contrast to an earlier peak assignment-we show that the two distinct Fe species (A and B site) and the charge modulation at the B site are responsible for the newly found double peaks in the main peak above T_{V} and its T-dependent evolution. The Fe 2p HAXPES spectra show a clear magnetic circular dichroism (MCD) in the metallic phase of magnetized 100-nm-thick films. The model calculations also reproduce the MCD and identify the contributions from magnetically distinct A and B sites. Valence band HAXPES shows a finite density of states at E_{F} for the polaronic half metal with a remnant order above T_{V} and a clear gap formation below T_{V}. The results indicate that the Verwey transition is driven by changes in the strongly correlated and magnetically active B-site electronic states, consistent with resistivity and optical spectra.
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Affiliation(s)
- M Taguchi
- Material Science, Nara Institute of Science and Technology (NAIST), Ikoma, Nara 630-0192, Japan
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - A Chainani
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - S Ueda
- National Institute for Materials Science (NIMS), SPring-8, Sayo, Hyogo 679-5148, Japan
| | - M Matsunami
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Y Ishida
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - R Eguchi
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - S Tsuda
- National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0003, Japan
| | - Y Takata
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - M Yabashi
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - K Tamasaku
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - Y Nishino
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - T Ishikawa
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - H Daimon
- Material Science, Nara Institute of Science and Technology (NAIST), Ikoma, Nara 630-0192, Japan
| | - S Todo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - H Tanaka
- ISIR-Sanken, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - M Oura
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - Y Senba
- JASRI/SPring-8, Sayo, Sayo, Hyogo 679-5198, Japan
| | - H Ohashi
- JASRI/SPring-8, Sayo, Sayo, Hyogo 679-5198, Japan
| | - S Shin
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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32
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Shu H, Luo P, Liang P, Cao D, Chen X. Layer-dependent dopant stability and magnetic exchange coupling of iron-doped MoS2 nanosheets. ACS APPLIED MATERIALS & INTERFACES 2015; 7:7534-7541. [PMID: 25805357 DOI: 10.1021/am508843z] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using density-functional theory calculations including a Hubbard U term we explore structural stability, electronic and magnetic properties of Fe-doped MoS2 nanosheets. Unlike previous reports, the geometry and the stability of Fe dopant atoms in MoS2 nanosheets strongly depend on the chemical potential and the layer number of sheets. The substitution Fe dopant atoms at the Mo sites are energetically favorable in monolayer MoS2 and the formation of intercalated and substitutional Fe complexes are preferred in bilayer and multilayer ones under the S-rich regime that is a popular condition for the synthesis of MoS2 nanosheets. We find that the Fe dopants prefer to the ferromagnetic coupling in monolayer MoS2 and the antiferromagnetic coupling in bilayer and multilayer ones, suggesting the layer dependence of magnetic exchange coupling (MEC). The transition of MEC in Fe-doped MoS2 sheets induced by the change of layer number arises from the competition mechanism between the double-exchange and superexchange couplings. The findings provide a route to facilitate the design of MoS2-based diluted magnetic semiconductors and spintronic devices.
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Affiliation(s)
- Haibo Shu
- ‡National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Science, 200083 Shanghai, China
| | | | | | | | - Xiaoshuang Chen
- ‡National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Science, 200083 Shanghai, China
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33
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Guo W, He Z, Tang Y, Zhang S, Yang M, Cheng W. BaMn9II(VO4)6(OH)2: a homospin ferrimagnet with a broken spinel-lattice of B-sites. Dalton Trans 2015; 44:6363-7. [DOI: 10.1039/c4dt02930e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new homospin ferrimagnet BaMn9II(VO4)6(OH)2 exhibits a unique structural feature with a reverse triangular dipyramid Mn7 spin lattice, in which such a lattice can be considered as a broken spin lattice of B-sites in spinel compounds.
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Affiliation(s)
- Wenbin Guo
- State Key Laboratory of Structural Chemistry
- Fujian Institute of Research on the Structure of Matter
- Chinese Academy of Sciences
- Fuzhou 350002
- P. R. China
| | - Zhangzhen He
- State Key Laboratory of Structural Chemistry
- Fujian Institute of Research on the Structure of Matter
- Chinese Academy of Sciences
- Fuzhou 350002
- P. R. China
| | - Yingying Tang
- State Key Laboratory of Structural Chemistry
- Fujian Institute of Research on the Structure of Matter
- Chinese Academy of Sciences
- Fuzhou 350002
- P. R. China
| | - Suyun Zhang
- State Key Laboratory of Structural Chemistry
- Fujian Institute of Research on the Structure of Matter
- Chinese Academy of Sciences
- Fuzhou 350002
- P. R. China
| | - Ming Yang
- State Key Laboratory of Structural Chemistry
- Fujian Institute of Research on the Structure of Matter
- Chinese Academy of Sciences
- Fuzhou 350002
- P. R. China
| | - Wendan Cheng
- State Key Laboratory of Structural Chemistry
- Fujian Institute of Research on the Structure of Matter
- Chinese Academy of Sciences
- Fuzhou 350002
- P. R. China
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34
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Schmitz D, Schmitz-Antoniak C, Warland A, Darbandi M, Haldar S, Bhandary S, Eriksson O, Sanyal B, Wende H. The dipole moment of the spin density as a local indicator for phase transitions. Sci Rep 2014; 4:5760. [PMID: 25041757 PMCID: PMC4104392 DOI: 10.1038/srep05760] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 07/02/2014] [Indexed: 11/17/2022] Open
Abstract
The intra-atomic magnetic dipole moment - frequently called 〈Tz〉 term - plays an important role in the determination of spin magnetic moments by x-ray absorption spectroscopy for systems with nonspherical spin density distributions. In this work, we present the dipole moment as a sensitive monitor to changes in the electronic structure in the vicinity of a phase transiton. In particular, we studied the dipole moment at the Fe2+ and Fe3+ sites of magnetite as an indicator for the Verwey transition by a combination of x-ray magnetic circular dichroism and density functional theory. Our experimental results prove that there exists a local change in the electronic structure at temperatures above the Verwey transition correlated to the known spin reorientation. Furthermore, it is shown that measurement of the dipole moment is a powerful tool to observe this transition in small magnetite nanoparticles for which it is usually screened by blocking effects in classical magnetometry.
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Affiliation(s)
- D Schmitz
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - C Schmitz-Antoniak
- 1] Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany [2]
| | - A Warland
- Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany
| | - M Darbandi
- 1] Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany [2]
| | - S Haldar
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box-516, SE 75120 Uppsala, Sweden
| | - S Bhandary
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box-516, SE 75120 Uppsala, Sweden
| | - O Eriksson
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box-516, SE 75120 Uppsala, Sweden
| | - B Sanyal
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box-516, SE 75120 Uppsala, Sweden
| | - H Wende
- Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany
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35
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36
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Ab Initio Research on a New Type of Half-Metallic Double Perovskites, A2CrMO6 (A = IVA Group Elements; M = Mo, Re and W). COMPUTATION 2014. [DOI: 10.3390/computation2010012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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37
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Yamauchi K, Barone P. Electronic ferroelectricity induced by charge and orbital orderings. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:103201. [PMID: 24552672 DOI: 10.1088/0953-8984/26/10/103201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
After the revival of the magnetoelectric effect which took place in the early 2000s, the interest in multiferroic materials displaying simultaneous presence of spontaneous long-range magnetic and dipolar order has motivated an exponential growth of research activity, from both the experimental and theoretical perspectives. Within this context, and relying also on the rigorous formulation of macroscopic polarization as provided by the Berry-phase approach, it has been possible to identify new microscopic mechanisms responsible for the appearance of ferroelectricity. In particular, it has been realized that electronic spin, charge and orbital degrees of freedom may be responsible for the breaking of the space-inversion symmetry, a necessary condition for the appearance of electric polarization, even in centrosymmetric crystal structures. In view of its immediate potential application in magnetoelectric-based devices, many efforts have been made to understand how magnetic orderings may lead to ferroelectric polarization, and to identify candidate materials. On the other hand, the role of charge and orbital degrees of freedom, which have received much less attention, has been predicted to be non-negligible in several cases. Here, we review recent theoretical advances in the field of so-called electronic ferroelectricity, focusing on the possible mechanisms by which charge- and/or orbital-ordering effects may cause the appearance of macroscopic polarization. Generally, a naive distinction can be drawn between materials displaying almost localized electrons and those characterized by a strong covalent character and delocalized electrons. As for the latter, an intuitive understanding of basic mechanisms is provided in the framework of tight-binding model Hamiltonians, which are used to shed light on unusual charge/orbital effects in half-doped manganites, whereas the case of magnetite will be thoroughly discussed in light of recent progress pointing to an electronic origin of its proposed ferroelectric and magnetoelectric properties.
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Affiliation(s)
- Kunihiko Yamauchi
- ISIR-SANKEN, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
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38
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Li D, Song C, He HY, Liu CS, Pan BC. An atomistic insight into the corrosion of the oxide film in liquid lead–bismuth eutectic. Phys Chem Chem Phys 2014; 16:7417-22. [DOI: 10.1039/c3cp54377c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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39
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Arras R, Warot-Fonrose B, Calmels L. Electronic structure near cationic defects in magnetite. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:256002. [PMID: 23719291 DOI: 10.1088/0953-8984/25/25/256002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We used the DFT + U method to describe the modification of the physical properties induced by cationic point defects in cubic magnetite Fe3O4. We considered the case of Fe vacancies and interstitial atoms in non-stoichiometric magnetite, and of Frenkel defects in a stoichiometric crystal. For each of these defects, we give results on the modification of the magnetic moment of atoms near the defect. We describe the local reorganization of the electric charge which is responsible for changes in the average oxidation degree of Fe atoms. We show that gap states, when they exist, do not destroy the half-metallic character of magnetite. Fe defects, however, change the filling of bands crossing the Fermi level and must be mostly responsible for a decrease in the magnetization.
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Affiliation(s)
- R Arras
- CEMES, CNRS and Université de Toulouse, Toulouse, France.
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40
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Hoesch M, Piekarz P, Bosak A, Le Tacon M, Krisch M, Kozłowski A, Oleś AM, Parlinski K. Anharmonicity due to electron-phonon coupling in magnetite. PHYSICAL REVIEW LETTERS 2013; 110:207204. [PMID: 25167445 DOI: 10.1103/physrevlett.110.207204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Indexed: 05/22/2023]
Abstract
We present the results of inelastic x-ray scattering for magnetite and analyze the energies and widths of the phonon modes with different symmetries in a broad range of temperature 125 < T < 293 K. The phonon modes with X(4) and Δ(5) symmetries broaden in a nonlinear way with decreasing T when the Verwey transition is approached. It is found that the maxima of phonon widths occur away from high-symmetry points, which suggests the incommensurate character of critical fluctuations. Strong phonon anharmonicity induced by electron-phonon coupling is discovered by a combination of these experimental results with ab initio calculations which take into account local Coulomb interactions at Fe ions. It (i) explains observed anomalous phonon broadening and (ii) demonstrates that the Verwey transition is a cooperative phenomenon which involves a wide spectrum of phonons coupled to the electron charge fluctuations condensing in the low-symmetry phase.
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Affiliation(s)
- Moritz Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, Oxfordshire, United Kingdom
| | - Przemysław Piekarz
- Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, PL-31342 Kraków, Poland
| | - Alexey Bosak
- European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble Cedex, France
| | - Mathieu Le Tacon
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Michael Krisch
- European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble Cedex, France
| | - Andrzej Kozłowski
- Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Aleja Mickiewicza 30, PL-30059 Kraków, Poland
| | - Andrzej M Oleś
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany and Marian Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, PL-30059 Kraków, Poland
| | - Krzysztof Parlinski
- Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, PL-31342 Kraków, Poland
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41
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Fink J, Schierle E, Weschke E, Geck J. Resonant elastic soft x-ray scattering. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2013; 76:056502. [PMID: 23563216 DOI: 10.1088/0034-4885/76/5/056502] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Resonant (elastic) soft x-ray scattering (RSXS) offers a unique element, site and valence specific probe to study spatial modulations of charge, spin and orbital degrees of freedom in solids on the nanoscopic length scale. It is not only used to investigate single-crystalline materials. This method also enables one to examine electronic ordering phenomena in thin films and to zoom into electronic properties emerging at buried interfaces in artificial heterostructures. During the last 20 years, this technique, which combines x-ray scattering with x-ray absorption spectroscopy, has developed into a powerful probe to study electronic ordering phenomena in complex materials and furthermore delivers important information on the electronic structure of condensed matter. This review provides an introduction to the technique, covers the progress in experimental equipment, and gives a survey on recent RSXS studies of ordering in correlated electron systems and at interfaces.
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Affiliation(s)
- J Fink
- Leibniz-Institute for Solid State and Materials Research Dresden, PO Box 270116, D-01171 Dresden, Germany.
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Lee J, Han S. Thermodynamics of native point defects in α-Fe2O3: an ab initio study. Phys Chem Chem Phys 2013; 15:18906-14. [DOI: 10.1039/c3cp53311e] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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43
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Ju S, Cai TY, Lu HS, Gong CD. Pressure-Induced Crystal Structure and Spin-State Transitions in Magnetite (Fe3O4). J Am Chem Soc 2012; 134:13780-6. [DOI: 10.1021/ja305167h] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sheng Ju
- Department
of Physics and Jiangsu
Key Laboratory of Thin Films, Soochow University, Suzhou 215006, P. R. China
| | - Tian-Yi Cai
- Department
of Physics and Jiangsu
Key Laboratory of Thin Films, Soochow University, Suzhou 215006, P. R. China
| | - Hai-Shuang Lu
- Department
of Physics and Jiangsu
Key Laboratory of Thin Films, Soochow University, Suzhou 215006, P. R. China
| | - Chang-De Gong
- Center for Statistical and Theoretical
Condensed Matter Physics and Department of Physics, Zhejiang Normal University, Jinhua 321004, P. R. China
- National Laboratory of Solid State
Microstructure and Department of Physics, Nanjing University, Nanjing 210093, P. R. China
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44
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Tanaka A, Chang CF, Buchholz M, Trabant C, Schierle E, Schlappa J, Schmitz D, Ott H, Metcalf P, Tjeng LH, Schüßler-Langeheine C. Symmetry of orbital order in Fe3O4 studied by Fe L(2,3) resonant x-ray diffraction. PHYSICAL REVIEW LETTERS 2012; 108:227203. [PMID: 23003646 DOI: 10.1103/physrevlett.108.227203] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2011] [Indexed: 06/01/2023]
Abstract
We studied the symmetry of the Fe 3d wave function in magnetite below the Verwey temperature T(V) with resonant soft-x-ray diffraction. Although the lattice structure of the low-temperature phase of Fe(3)O(4) is well described by the pseudo-orthorhombic Pmca with a slight monoclinic P2/c distortion, we find that the 3d wave function does not reflect the Pmca symmetry, and its distortion toward monoclinic symmetry is by far larger than that of the lattice. The result supports a scenario in which the Verwey transition involves the ordering of t(2g) orbitals with complex-number coefficients.
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Affiliation(s)
- A Tanaka
- Department of Quantum Matters, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
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45
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Subías G, García J, Blasco J, Herrero-Martín J, Sánchez MC, Orna J, Morellón L. Structural distortion, charge modulation and local anisotropies in magnetite below the Verwey transition using resonant X-ray scattering. JOURNAL OF SYNCHROTRON RADIATION 2012; 19:159-173. [PMID: 22338674 DOI: 10.1107/s0909049512001367] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 01/11/2012] [Indexed: 05/31/2023]
Abstract
The pattern of charge modulations and local anisotropies below the Verwey transition has been determined and quantified in high-quality Fe(3)O(4) single crystals and thin films grown on MgO by using resonant X-ray scattering at the Fe K-edge. The energy, polarization and azimuthal angle dependencies of an extensive set of reflections with potential sensitivity to charge or local anisotropy orderings have been analyzed to explore their origins. A charge disproportion on octahedral B sites of 0.20 ± 0.05 e(-) with [0 0 1] and [1 1 0] cubic periodicities has been confirmed, while no significant charge disproportion has been obtained with [0 0 1/2] cubic periodicity. Additional charge modulations in the monoclinic a-b plane are also present. In addition, the occurrence of new forbidden (1, 1, 0) and (0, 0, 2n + 1/2) cubic reflections that arise from the anisotropy of the local structure around different tetrahedral and octahedral Fe atoms is shown. This complex pattern of weak charge modulations and local anisotropies is fully compatible with the low-temperature crystal structure refined in the non-polar C2/c space group and disproves any bimodal charge disproportion of the octahedral Fe atoms.
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Affiliation(s)
- Gloria Subías
- Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, Departamento de Física de Materia Condensada, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
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46
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Ziese M, Esquinazi PD, Pantel D, Alexe M, Nemes NM, Garcia-Hernández M. Magnetite (Fe3O4): a new variant of relaxor multiferroic? JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:086007. [PMID: 22314835 DOI: 10.1088/0953-8984/24/8/086007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The electric polarization, dielectric permittivity, magnetoelectric effect, heat capacity, magnetization and ac susceptibility of magnetite films and polycrystals were investigated. The electric polarization of magnetite films with saturation values between 4 and 8 μC cm(-2) was found to vanish between 32 and 38 K, but in polycrystals no phase transition was detected in this range by heat capacity. Both types of samples showed magnetoelectric effects at low temperatures below a frequency-dependent crossover. This is interpreted as arising from multiferroic relaxor behavior.
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Affiliation(s)
- M Ziese
- Division of Superconductivity and Magnetism, Faculty of Physics and Geosciences, University of Leipzig, Leipzig, Germany.
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47
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Charge order and three-site distortions in the Verwey structure of magnetite. Nature 2011; 481:173-6. [PMID: 22190035 DOI: 10.1038/nature10704] [Citation(s) in RCA: 181] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 11/08/2011] [Indexed: 11/08/2022]
Abstract
The mineral magnetite (Fe(3)O(4)) undergoes a complex structural distortion and becomes electrically insulating at temperatures less than 125 kelvin. Verwey proposed in 1939 that this transition is driven by a charge ordering of Fe(2+) and Fe(3+) ions, but the ground state of the low-temperature phase has remained contentious because twinning of crystal domains hampers diffraction studies of the structure. Recent powder diffraction refinements and resonant X-ray studies have led to proposals of a variety of charge-ordered and bond-dimerized ground-state models. Here we report the full low-temperature superstructure of magnetite, determined by high-energy X-ray diffraction from an almost single-domain, 40-micrometre grain, and identify the emergent order. The acentric structure is described by a superposition of 168 atomic displacement waves (frozen phonon modes), all with amplitudes of less than 0.24 ångströms. Distortions of the FeO(6) octahedra show that Verwey's hypothesis is correct to a first approximation and that the charge and Fe(2+) orbital order are consistent with a recent prediction. However, anomalous shortening of some Fe-Fe distances suggests that the localized electrons are distributed over linear three-Fe-site units, which we call 'trimerons'. The charge order and three-site distortions induce substantial off-centre atomic displacements and couple the resulting large electrical polarization to the magnetization. Trimerons may be important quasiparticles in magnetite above the Verwey transition and in other transition metal oxides.
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48
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Sit PHL, Car R, Cohen MH, Selloni A. Simple, Unambiguous Theoretical Approach to Oxidation State Determination via First-Principles Calculations. Inorg Chem 2011; 50:10259-67. [DOI: 10.1021/ic2013107] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Patrick H.-L. Sit
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Roberto Car
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
- Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States
| | - Morrel H. Cohen
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
| | - Annabella Selloni
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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Cheng YH, Li LY, Wang WH, Liu H, Ren SW, Cui XY, Zheng RK. Tunable electrical and magnetic properties of half-metallic ZnxFe3−xO4 from first principles. Phys Chem Chem Phys 2011; 13:21243-7. [DOI: 10.1039/c1cp22463h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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50
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Kumar A, Kumar P, Waghmare UV, Sood AK. First-principles analysis of electron correlation, spin ordering and phonons in the normal state of FeSe 1-x. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:385701. [PMID: 21386556 DOI: 10.1088/0953-8984/22/38/385701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present first-principles density-functional-theory-based calculations to determine the effects of the strength of on-site electron correlation, magnetic ordering, pressure and Se vacancies on phonon frequencies and electronic structure of FeSe(1 - x). The theoretical equilibrium structure (lattice parameters) of FeSe depends sensitively on the value of the Hubbard parameter U of on-site correlation and magnetic ordering. Our results suggest that there is a competition between different antiferromagnetic states due to comparable magnetic exchange couplings between first- and second-neighbor Fe sites. As a result, a short range order of stripe antiferromagnetic type is shown to be relevant to the normal state of FeSe at low temperature. We show that there is a strong spin-phonon coupling in FeSe (comparable to its superconducting transition temperature) as reflected in large changes in the frequencies of certain phonons with different magnetic ordering, which is used to explain the observed hardening of a Raman-active phonon at temperatures (∼100 K) where magnetic ordering sets in. The symmetry of the stripe antiferromagnetic phase permits an induced stress with orthorhombic symmetry, leading to orthorhombic strain as a secondary order parameter at the temperature of magnetic ordering. The presence of Se vacancies in FeSe gives rise to a large peak in the density of states near the Fermi energy, which could enhance the superconducting transition temperature within the BCS-like picture.
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Affiliation(s)
- Anil Kumar
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560064, India
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