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Okamoto J, Wang RP, Chu YY, Shiu HW, Singh A, Huang HY, Mou CY, Teh S, Jeng HT, Du K, Xu X, Cheong SW, Du CH, Chen CT, Fujimori A, Huang DJ. Giant X-Ray Circular Dichroism in a Time-Reversal Invariant Antiferromagnet. Adv Mater 2024:e2309172. [PMID: 38391035 DOI: 10.1002/adma.202309172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 02/09/2024] [Indexed: 02/24/2024]
Abstract
X-ray circular dichroism, arising from the contrast in X-ray absorption between opposite photon helicities, serves as a spectroscopic tool to measure the magnetization of ferromagnetic materials and identify the handedness of chiral crystals. Antiferromagnets with crystallographic chirality typically lack X-ray magnetic circular dichroism because of time-reversal symmetry, yet exhibit weak X-ray natural circular dichroism. Here, the observation of giant natural circular dichroism in the Ni L3-edge X-ray absorption of Ni3TeO6 is reported, a polar and chiral antiferromagnet with effective time-reversal symmetry. To unravel this intriguing phenomenon, a phenomenological model is proposed that classifies the movement of photons in a chiral crystal within the same symmetry class as that of a magnetic field. The coupling of X-ray polarization with the induced magnetization yields giant X-ray natural circular dichroism, revealing typical ferromagnetic behaviors allowed by the symmetry in an antiferromagnet, i.e., the altermagnetism of Ni3TeO6. The findings provide evidence for the interplay between magnetism and crystal chirality in natural optical activity. Additionally, the first example of a new class of magnetic materials exhibiting circular dichroism is established with time-reversal symmetry.
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Affiliation(s)
- Jun Okamoto
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Ru-Pan Wang
- Department of Physics, University of Hamburg, Luruper Chaussee 149, G610, 22761, Hamburg, Germany
| | - Yen-Yi Chu
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Hung-Wei Shiu
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Amol Singh
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Hsiao-Yu Huang
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Chung-Yu Mou
- Center for Quantum Science and Technology and Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Sukhito Teh
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Kai Du
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854, USA
| | - Xianghan Xu
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854, USA
| | - Sang-Wook Cheong
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854, USA
| | - Chao-Hung Du
- Department of Physics, Tamkang University, Tamsui, 251, Taiwan
| | - Chien-Te Chen
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Atsushi Fujimori
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
- Center for Quantum Science and Technology and Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
- Department of Physics, University of Tokyo, Bunkyo-Ku, Tokyo, 113-0033, Japan
| | - Di-Jing Huang
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, 30093, Taiwan
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2
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Mei R, Zhao YF, Wang C, Ren Y, Xiao D, Chang CZ, Liu CX. Electrically Controlled Anomalous Hall Effect and Orbital Magnetization in Topological Magnet MnBi_{2}Te_{4}. Phys Rev Lett 2024; 132:066604. [PMID: 38394580 DOI: 10.1103/physrevlett.132.066604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 12/22/2023] [Indexed: 02/25/2024]
Abstract
We propose an intrinsic mechanism to understand the even-odd effect, namely, opposite signs of anomalous Hall resistance and different shapes of hysteresis loops for even and odd septuple layers (SLs), of MBE-grown MnBi_{2}Te_{4} thin films with electron doping. The nonzero hysteresis loops in the anomalous Hall effect and magnetic circular dichroism for even-SLs MnBi_{2}Te_{4} films originate from two different antiferromagnetic (AFM) configurations with different zeroth Landau level energies of surface states. The complex form of the anomalous Hall hysteresis loop can be understood from two magnetic transitions, a transition between two AFM states followed by a second transition to the ferromagnetic state. Our model also clarifies the relationship and distinction between axion parameter and magnetoelectric coefficient, and shows an even-odd oscillation behavior of magnetoelectric coefficients in MnBi_{2}Te_{4} films.
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Affiliation(s)
- Ruobing Mei
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Yi-Fan Zhao
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Chong Wang
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA
| | - Yafei Ren
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA
| | - Di Xiao
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Cui-Zu Chang
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Chao-Xing Liu
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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3
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Zhang S, Li K, Ma Y, Bu Y, Liang Z, Yang Z, Zhang J. The Adsorption Mechanism of Hydrogen on FeO Crystal Surfaces: A Density Functional Theory Study. Nanomaterials (Basel) 2023; 13:2051. [PMID: 37513062 PMCID: PMC10384720 DOI: 10.3390/nano13142051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/07/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023]
Abstract
The hydrogen-based direct reduction of iron ores is a disruptive routine used to mitigate the large amount of CO2 emissions produced by the steel industry. The reduction of iron oxides by H2 involves a variety of physicochemical phenomena from macroscopic to atomistic scales. Particularly at the atomistic scale, the underlying mechanisms of the interaction of hydrogen and iron oxides is not yet fully understood. In this study, density functional theory (DFT) was employed to investigate the adsorption behavior of hydrogen atoms and H2 on different crystal FeO surfaces to gain a fundamental understanding of the associated interfacial adsorption mechanisms. It was found that H2 molecules tend to be physically adsorbed on the top site of Fe atoms, while Fe atoms on the FeO surface act as active sites to catalyze H2 dissociation. The dissociated H atoms were found to prefer to be chemically bonded with surface O atoms. These results provide a new insight into the catalytic effect of the studied FeO surfaces, by showing that both Fe (catalytic site) and O (binding site) atoms contribute to the interaction between H2 and FeO surfaces.
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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 Dusseldorf, Germany
| | - Yushan Bu
- 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
| | - Zonghao Yang
- 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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4
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Umeda M, Chudo H, Imai M, Sato N, Saitoh E. Temperature-variable apparatus for measuring Barnett field. Rev Sci Instrum 2023; 94:063906. [PMID: 37862522 DOI: 10.1063/5.0142318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 05/31/2023] [Indexed: 10/22/2023]
Abstract
We have developed experimental equipment for observing the Barnett effect, in which mechanical rotation magnetizes an object, at low temperatures. A sample in a rotor is rotated bidirectionally using a temperature-controlled high-pressure gas. The stray field generated from the sample due to the Barnett effect was detected using a fluxgate magnetic sensor with a sensitivity on the order of several picoteslas, even at low temperatures. By replacing the rotor with a solenoid coil, the magnetic susceptibility of the sample was estimated from the stray field to be of the same order of magnitude as that due to the Barnett effect. The Barnett field was estimated using the dipole model. To assess the performance of the setup at low temperatures, measurements were performed on commercial magnetite (Fe3O4) nanogranules. We confirmed the accordance of the g' factor between the experimental results using the present setup and those of our previous study performed at room temperature.
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Affiliation(s)
- Maki Umeda
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Hiroyuki Chudo
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Masaki Imai
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Nana Sato
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Eiji Saitoh
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
- Department of Applied Physics, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Institute for AI and Beyond, The University of Tokyo, Tokyo 113-8656, Japan
- Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
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5
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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) 2022; 15:8316. [PMID: 36499813 PMCID: PMC9740064 DOI: 10.3390/ma15238316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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6
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Gu F, Zhang L, Li Z, Zhang J, Pan Y, Li Q, Li H, Qin Y, Li Q. A comparative study of electrochemical and electrostatic doping modulation of magnetism in Fe 3O 4via ultracapacitor structure. J Phys Condens Matter 2022; 34:455802. [PMID: 36044895 DOI: 10.1088/1361-648x/ac8e47] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 08/31/2022] [Indexed: 06/15/2023]
Abstract
Electric field control of magnetism can boost energy efficiency and have brought revolutionary breakthroughs in the development of widespread applications in spintronics. Electrolyte gating plays an important role in magnetism modulation. In this work, reversible room-temperature electric field control of saturation magnetization in Fe3O4via a supercapacitor structure is demonstrated with three types of traditional gate electrolytes for comparison. Different magnetization response and responsible mechanisms are revealed by Operando magnetometry PPMS/VSM and XPS characterization. The main mechanism in Na2SO4, KOH aqueous electrolytes is electrochemical effect, while both electrochemical and electrostatic effects were found in LiPF6organic electrolyte. This work offers a kind of reference basis for selecting appropriate electrolyte in magnetism modulation by electrolyte-gating in the future, meanwhile, paves its way towards practical use in magneto-electric actuation, voltage-assisted magnetic storage, facilitating the development of high-performance spintronic devices.
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Affiliation(s)
- Fangchao Gu
- College of Physics, University-Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, Qingdao 266071, People's Republic of China
| | - Leqing Zhang
- College of Physics, University-Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, Qingdao 266071, People's Republic of China
| | - Zhaohui Li
- College of Physics, University-Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, Qingdao 266071, People's Republic of China
| | - Jie Zhang
- College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
| | - Yuanyuan Pan
- College of Physics, University-Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, Qingdao 266071, People's Republic of China
| | - Qinghao Li
- College of Physics, University-Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, Qingdao 266071, People's Republic of China
| | - Hongsen Li
- College of Physics, University-Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, Qingdao 266071, People's Republic of China
| | - Yufeng Qin
- College of Information Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, People's Republic of China
| | - Qiang Li
- College of Physics, University-Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, Qingdao 266071, People's Republic of China
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7
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Liu W, Liu L, Cheng B, Qin H, Zhou G, Cui B, Hu J. Electrical Control of Magnetism through Proton Migration in Fe 3O 4/Graphene Heterostructure. Nano Lett 2022; 22:4392-4399. [PMID: 35616440 DOI: 10.1021/acs.nanolett.2c00838] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ion migration has direct and crucial bearing on the crystal lattice field, electron filling, orbital occupation and spin polarization, which in turn changes the physical properties. Electric field is an effective way to control ion migration, but it may include simultaneous movement of multiple ions and increase the complexity of the system. Therefore, controllable and selective single ion migration with an unambiguous mechanism is highly desired. Here, the magnetic moments of Fe3O4 could be reversibly controlled by ionic liquid gating on the basis of migration of pure protons. A bilayer graphene could serve as an ion sieve, allowing only protons rather than oxygen ions or hydroxyl groups to participate in the gating process, thus guaranteeing the reversibility of magnetic property changes. This work is expected to supply an ideal arena for electrically sketching the functionalities of solid state materials based on the selective ion migration.
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Affiliation(s)
- Weikang Liu
- School of Physics, State Key Laboratory for Crystal Materials, Shandong University, Jinan 250100, China
| | - Liang Liu
- School of Physics, State Key Laboratory for Crystal Materials, Shandong University, Jinan 250100, China
| | - Bin Cheng
- School of Physics, State Key Laboratory for Crystal Materials, Shandong University, Jinan 250100, China
| | - Hongwei Qin
- School of Physics, State Key Laboratory for Crystal Materials, Shandong University, Jinan 250100, China
| | - Guangjun Zhou
- School of Physics, State Key Laboratory for Crystal Materials, Shandong University, Jinan 250100, China
| | - Bin Cui
- School of Physics, State Key Laboratory for Crystal Materials, Shandong University, Jinan 250100, China
| | - Jifan Hu
- School of Physics, State Key Laboratory for Crystal Materials, Shandong University, Jinan 250100, China
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8
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Dawn R, Zzaman M, Faizal F, Kiran C, Kumari A, Shahid R, Panatarani C, Joni IM, Verma VK, Sahoo SK, Amemiya K, Singh VR. Origin of Magnetization in Silica-coated Fe 3O 4 Nanoparticles Revealed by Soft X-ray Magnetic Circular Dichroism. Braz J Phys 2022; 52:99. [PMCID: PMC9014780 DOI: 10.1007/s13538-022-01102-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 03/31/2022] [Indexed: 05/24/2023]
Abstract
Abstract
Magnetite (Fe3O4) nanoparticles (NPs) and SiO2-coated Fe3O4 nanoparticles have successfully been synthesized using co-precipitation and modified Stöber methods, respectively. The samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscopy (HRTEM), vibrating sample magnetometer (VSM) techniques, X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD). XRD and FTIR data confirmed the structural configuration of a single-phase Fe3O4 and the successful formation of SiO2-coated Fe3O4 NPs. XRD also confirmed that we have succeeded to synthesize nano-meter size of Fe3O4 NPs. HRTEM images showed the increasing thickness of SiO2-coated Fe3O4 with the addition of the Tetraethyl Orthosilicate (TEOS). Room temperature VSM analysis showed the magnetic behaviour of Fe3O4 and its variations that occurred after SiO2 coating. The magnetic behaviour is further authenticated by XAS spectra analysis which cleared about the existence of SiO2 shells that have transformed the crystal as well as the local structures of the magnetite NPs. We have performed XMCD measurements, which is a powerful element-specific technique to find out the origin of magnetization in SiO2-coated Fe3O4 NPs, that verified a decrease in magnetization with increasing thickness of the SiO2 coating. Graphical Abstract Magnetite (Fe3O4) nanoparticles (NPs) and SiO2-coated Fe3O4 nanoparticles have successfully been synthesized using co-precipitation and modified Stöber methods, respectively. The samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscopy (HRTEM), vibrating sample magnetometer (VSM) techniques, X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD). XRD and FTIR data confirmed the structural configuration of a single-phase Fe3O4 and the successful formation of SiO2-coated Fe3O4 NPs. XRD also confirmed that we have succeeded to synthesize nano-meter size of Fe3O4 NPs. HRTEM images showed the increasing thickness of SiO2-coated Fe3O4 with the addition of the Tetraethyl Orthosilicate (TEOS). Room temperature VSM analysis showed the magnetic behaviour of Fe3O4 and its variations that occurred after SiO2 coating. The magnetic behaviour is further authenticated by XAS spectra analysis which cleared about the existence of SiO2 shells that have transformed the crystal as well as the local structures of the magnetite NPs. We have performed XMCD measurements, which is a powerful element-specific technique to find out the origin of magnetization in SiO2-coated Fe3O4 NPs, that verified a decrease in magnetization with increasing thickness of the SiO2 coating. ![]()
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Affiliation(s)
- R. Dawn
- Department of Physics, Central University of South Bihar, Gaya-824236, India
| | - M. Zzaman
- Department of Physics, Central University of South Bihar, Gaya-824236, India
- Department of Physics, Jamia Millia Islamia (Central University), New Delhi, 110025 India
| | - F. Faizal
- Department of Physics, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang Km 21, West Java, Bandung, 45363 Indonesia
- Functional Nano Powder University Centre of Excellence (FiNder U CoE), Universitas Padjadjaran, Jl. Raya Bandung-Sumedang, Km 21, West Java, Bandung, 45363 Indonesia
| | - C. Kiran
- Department of Animal Sciences, Central University of Kashmir, Ganderbal, 191201 India
| | - A. Kumari
- Department of Physics, Central University of South Bihar, Gaya-824236, India
| | - R. Shahid
- Department of Physics, Jamia Millia Islamia (Central University), New Delhi, 110025 India
| | - C. Panatarani
- Department of Physics, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang Km 21, West Java, Bandung, 45363 Indonesia
- Functional Nano Powder University Centre of Excellence (FiNder U CoE), Universitas Padjadjaran, Jl. Raya Bandung-Sumedang, Km 21, West Java, Bandung, 45363 Indonesia
| | - I. M. Joni
- Department of Physics, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang Km 21, West Java, Bandung, 45363 Indonesia
- Functional Nano Powder University Centre of Excellence (FiNder U CoE), Universitas Padjadjaran, Jl. Raya Bandung-Sumedang, Km 21, West Java, Bandung, 45363 Indonesia
| | - V. K. Verma
- Department of Physics, Madanapalle Institute of Technology & Science, Madanapalle, 517325 India
| | - S. K. Sahoo
- Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela, 769008 India
| | - K. Amemiya
- Photon Factory, IMSS, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 Japan
| | - V. R. Singh
- Department of Physics, Central University of South Bihar, Gaya-824236, India
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9
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Assadi MHN, Gutiérrez Moreno JJ, Hanaor DAH, Katayama-Yoshida H. Exceptionally high saturation magnetisation in Eu-doped magnetite stabilised by spin-orbit interaction. Phys Chem Chem Phys 2021; 23:20129-20137. [PMID: 34551040 DOI: 10.1039/d1cp02164h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The significance of the spin-orbit interaction is very well known in compounds containing heavier elements such as the rare-earth Eu ion. Here, through density functional calculations, we investigated the effect of the spin-orbit interaction on the magnetic ground state of Eu doped magnetite (Fe3O4:EuFe). By examining all possible spin alignments between Eu and magnetite's Fe, we demonstrate that Eu, which is most stable when doped at the tetrahedral site, adapts a spin almost opposite the substituted Fe. Consequently, because of smaller spin cancellation between the cations on the tetrahedral site (FeTet and EuTet) and the cations on the octahedral sites (FeOct), Fe3O4:EuFe exhibits a maximum saturation magnetisation of 9.451 μB per f.u. which is significantly larger than that of undoped magnetite (calculated to be 3.929 μB per f.u.). We further show that this large magnetisation persists through additional electron doping. However, additional hole doping, which may unintentionally occur in Fe deficient magnetite, can reduce the magnetisation to values smaller than that of the undoped magnetite. The results presented here can aid in designing highly efficient magnetically recoverable catalysts for which both magnetite and rare earth dopants are common materials.
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Affiliation(s)
- M Hussein N Assadi
- School of Materials Science and Engineering, The University of New South Wales, NSW 2052, Australia.
| | - José Julio Gutiérrez Moreno
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC), C/Jordi Girona 31, 08034 Barcelona, Spain
| | - Dorian A H Hanaor
- Fachgebiet Keramische Werkstoffe, Technische Universität Berlin, 10623 Berlin, Germany
| | - Hiroshi Katayama-Yoshida
- Center for Spintronics Research Network, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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10
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González-Alonso D, Espeso JI, Gavilán H, Zeng LJ, Fernández-Díaz MT, Subías G, de Pedro I, Fernández JR, Bender P, Barquín LF, Johansson C. Identifying the presence of magnetite in an ensemble of iron-oxide nanoparticles: a comparative neutron diffraction study between bulk and nanoscale. Nanoscale Adv 2021; 3:3491-3496. [PMID: 36133728 PMCID: PMC9419530 DOI: 10.1039/d0na00830c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 03/23/2021] [Indexed: 06/16/2023]
Abstract
Scientific interest in iron-oxides and in particular magnetite has been renewed due to the broad scope of their fascinating properties, which are finding applications in electronics and biomedicine. Specifically, iron oxide nanoparticles (IONPs) are gathering attraction in biomedicine. Their cores are usually constituted by a mixture of maghemite and magnetite phases. In view of this, to fine-tune the properties of an ensemble of IONPs towards their applications, it is essential to enhance mass fabrication processes towards the production of monodisperse IONPs with controlled size, shape, and stoichiometry. We exploit the vacancy sensitivity of the Verwey transition to detect the presence of magnetite. Here we provide direct evidence for the Verwey transition in an ensemble of IONPs through neutron diffraction. This transition is observed as a variation in the Fe magnetic moment at octahedral sites and, in turn, gives rise to a change of the net magnetic moment. Finally, we show this variation as the microscopic ingredient driving the characteristic kink that hallmarks the Verwey transition in thermal variation of magnetization.
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Affiliation(s)
- D González-Alonso
- Department CITIMAC, Faculty of Science, University of Cantabria 39005 Santander Spain
| | - J I Espeso
- Department CITIMAC, Faculty of Science, University of Cantabria 39005 Santander Spain
| | - H Gavilán
- Instituto de Ciencia de Materiales de Madrid, ICMM/CSIC 28049 Madrid Spain
| | - L J Zeng
- Department of Physics, Chalmers University of Technology 41296 Göteborg Sweden
| | | | - G Subías
- Instituto de Ciencia de Materiales de Aragón, Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza 50009 Zaragoza Spain
| | - I de Pedro
- Department CITIMAC, Faculty of Science, University of Cantabria 39005 Santander Spain
| | - J Rodríguez Fernández
- Department CITIMAC, Faculty of Science, University of Cantabria 39005 Santander Spain
| | - P Bender
- Department CITIMAC, Faculty of Science, University of Cantabria 39005 Santander Spain
| | - L Fernández Barquín
- Department CITIMAC, Faculty of Science, University of Cantabria 39005 Santander Spain
| | - C Johansson
- RISE Research Institutes of Sweden 411 33 Göteborg Sweden
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11
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Ji S, Jiang B, Hao H, Chen Y, Dong J, Mao Y, Zhang Z, Gao R, Chen W, Zhang R, Liang Q, Li H, Liu S, Wang Y, Zhang Q, Gu L, Duan D, Liang M, Wang D, Yan X, Li Y. Matching the kinetics of natural enzymes with a single-atom iron nanozyme. Nat Catal 2021. [DOI: 10.1038/s41929-021-00609-x] [Citation(s) in RCA: 176] [Impact Index Per Article: 58.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Tian F, Li Y, Zhao Q, Cao K, Wang D, Dai Z, Yu Z, Ke X, Zhang Y, Zhou C, Zuo W, Yang S, Song X. Giant exchange bias induced via tuning interfacial spins in polycrystalline Fe 3O 4/CoO bilayers. Phys Chem Chem Phys 2021; 23:4805-4810. [PMID: 33605273 DOI: 10.1039/d0cp05902a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A giant exchange bias (EB) of 9600 Oe was observed in polycrystalline Fe3O4/CoO layers at 10 K after 20 kOe field cooling, and was attributed to the strong exchange coupling formed by the interfacial spins between the polycrystalline Fe3O4 and the CoO layer. It was found that at 10 K, the magnetic-moment difference (ΔM) between the zero field cooling curves and field cooling curves first increases and then decreases with the change of the field, and it reaches the maximum value at a field of 20 kOe, which suggests that the interfacial spins can be tuned by the cooling field. Furthermore, other magnetic properties, including field dependence, temperature dependence, and training effects, were investigated, which further confirmed that the interfacial spins play an important role in the EB effect. This work provides a method to tune the magnitude of the EB effect and reveals the mechanism of the dependency of EB on interfacial spins, which could guide the design of giant-EB-effect materials.
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Affiliation(s)
- Fanghua Tian
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Yebei Li
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Qizhong Zhao
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Kaiyan Cao
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Dingchen Wang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Zhiyong Dai
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Zhonghai Yu
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Xiaoqin Ke
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Yin Zhang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Chao Zhou
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Wenliang Zuo
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Sen Yang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Xiaoping Song
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China.
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13
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Suturin SM, Korovin AM, Sitnikova AA, Kirilenko DA, Volkov MP, Dvortsova PA, Ukleev VA, Tabuchi M, Sokolov NS. Correlation between crystal structure and magnetism in PLD grown epitaxial films of ε-Fe 2O 3 on GaN. Sci Technol Adv Mater 2021; 22:85-99. [PMID: 35185387 PMCID: PMC8856044 DOI: 10.1080/14686996.2020.1870870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 12/25/2020] [Accepted: 12/29/2020] [Indexed: 06/14/2023]
Abstract
In the present paper we discuss correlations between crystal structure and magnetic properties of epitaxial ε-Fe2O3 films grown on GaN. The large magnetocrystalline anisotropy and room temperature multiferroic properties of this exotic iron oxide polymorph, make it a perspective material for the development of low power consumption magnetic media storage devices. Extending our recent progress in PLD growth of ε-Fe2O3 on the surface of technologically important nitride semiconductors, we apply reciprocal space tomography by electron and x-ray diffraction to investigate the break of crystallographic symmetry occurring at the oxide-nitride interface resulting in the appearance of anisotropic crystallographic disorder in the sub-100 nm ε-Fe2O3 films. The orthorhombic-on-hexagonal nucleation scenario is shown responsible for the development of a peculiar columnar structure observed in ε-Fe2O3 by means of HRTEM and AFM. The complementary information on the direct and reciprocal space structure of the columnar ε-Fe2O3 films is obtained by various techniques and correlated to their magnetic properties. The peculiar temperature dependence of magnetization studied by the small-field magnetization derivative method and by neutron diffraction reveals the existence of a magnetic softening below 150 K, similar to the one observed earlier solely in nanoparticles. The magnetization reversal in ε-Fe2O3 films probed by X-ray magnetic circular dichroism is found different from the behavior of the bulk averaged magnetization measured by conventional magnetometry. The presented results fill the gap between the numerous studies performed on randomly oriented ε-Fe2O3 nanoparticles and much less frequent investigations of epitaxial epsilon ferrite films with lattice orientation fixed by the substrate.
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Affiliation(s)
- Sergey M. Suturin
- Division of Solid State Physics, Division of Physics of Dielectrics and Semiconductors, Centre of Nanoheterostructure Physics, Ioffe Institute, St. Petersburg, Russia
| | - Alexander M. Korovin
- Division of Solid State Physics, Division of Physics of Dielectrics and Semiconductors, Centre of Nanoheterostructure Physics, Ioffe Institute, St. Petersburg, Russia
| | - Alla A. Sitnikova
- Division of Solid State Physics, Division of Physics of Dielectrics and Semiconductors, Centre of Nanoheterostructure Physics, Ioffe Institute, St. Petersburg, Russia
| | - Demid A. Kirilenko
- Division of Solid State Physics, Division of Physics of Dielectrics and Semiconductors, Centre of Nanoheterostructure Physics, Ioffe Institute, St. Petersburg, Russia
| | - Mikhail P. Volkov
- Division of Solid State Physics, Division of Physics of Dielectrics and Semiconductors, Centre of Nanoheterostructure Physics, Ioffe Institute, St. Petersburg, Russia
| | - Polina A. Dvortsova
- Division of Solid State Physics, Division of Physics of Dielectrics and Semiconductors, Centre of Nanoheterostructure Physics, Ioffe Institute, St. Petersburg, Russia
| | - Victor A. Ukleev
- Laboratory for Neutron Scattering and Imaging (LNS), Paul Scherrer Institute (PSI), Villigen, Switzerland
| | - Masao Tabuchi
- Synchrotron Radiation Research Center, Nagoya University, Nagoya, Japan
| | - Nikolai S. Sokolov
- Division of Solid State Physics, Division of Physics of Dielectrics and Semiconductors, Centre of Nanoheterostructure Physics, Ioffe Institute, St. Petersburg, Russia
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14
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Dudek G, Turczyn R, Djurado D. Collation Efficiency of Poly(Vinyl Alcohol) and Alginate Membranes with Iron-Based Magnetic Organic/Inorganic Fillers in Pervaporative Dehydration of Ethanol. Materials (Basel) 2020; 13:E4152. [PMID: 32961950 DOI: 10.3390/ma13184152] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 09/12/2020] [Accepted: 09/15/2020] [Indexed: 11/23/2022]
Abstract
Hybrid poly(vinyl alcohol) and alginate membranes were investigated in the process of ethanol dehydration by pervaporation. As a filler, three types of particles containing iron element, i.e., hematite, magnetite, and iron(III) acetyloacetonate were used. The parameters describing transport properties and effectiveness of investigated membranes were evaluated. Additionally, the physico-chemical properties of the resulting membranes were studied. The influence of polymer matrix, choice of iron particles and their content in terms of effectiveness of membranes in the process of ethanol dehydration were considered. The results showed that hybrid alginate membranes were characterized by a better separation factor, while poly(vinyl alcohol) membranes by a better flux. The best parameters were obtained for membranes filled with 7 wt% of iron(III) acetyloacetonate. The separation factor and pervaporative separation index were equal to 19.69 and 15,998 g⋅m−2⋅h−1 for alginate membrane and 11.75 and 14,878 g⋅m−2⋅h−1 for poly(vinyl alcohol) membrane, respectively.
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15
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Degaga GD, Trought M, Nemsak S, Crumlin EJ, Seel M, Pandey R, Perrine KA. Investigation of N 2 adsorption on Fe 3O 4(001) using ambient pressure X-ray photoelectron spectroscopy and density functional theory. J Chem Phys 2020; 152:054717. [PMID: 32035447 DOI: 10.1063/1.5138941] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Reactions on iron oxide surfaces are prevalent in various chemical processes from heterogeneous catalysts to minerals. Nitrogen (N2) is known to dissociate on iron surfaces, a precursor for ammonia production in the Haber-Bosch process, where the dissociation of N2 is the limiting step in the reaction under equilibrium conditions. However, little is known about N2 adsorption on other iron-based materials, such as iron oxide surfaces that are ubiquitous in soils, steel pipelines, and other industrial materials. An atomistic description is reported for the binding of N2 on the Fe3O4(001) surface using first principles calculations with ambient pressure X-ray photoelectron spectroscopy. Two primary adsorption sites are experimentally identified from N2 dissociation on Fe3O4(001). The electronic signatures associated with the valence band region unambiguously show how the electronic structure of magnetite transforms near ambient pressures due to the binding of atomic nitrogen to different surface sites. Overall, the experimental and theoretical results of our study bridge the gap between ultra-high vacuum studies and reaction conditions to provide insight into other nitrogen-based chemistry on iron oxide surfaces that impact the agriculture and energy industries.
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Affiliation(s)
- Gemechis D Degaga
- Department of Physics, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931-1295, USA
| | - Mikhail Trought
- Department of Chemistry, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931-1295, USA
| | - Slavomir Nemsak
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720-8229, USA
| | - Ethan J Crumlin
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720-8229, USA
| | - Max Seel
- Department of Physics, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931-1295, USA
| | - Ravindra Pandey
- Department of Physics, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931-1295, USA
| | - Kathryn A Perrine
- Department of Chemistry, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931-1295, USA
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16
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Elnaggar H, Sainctavit P, Juhin A, Lafuerza S, Wilhelm F, Rogalev A, Arrio MA, Brouder C, van der Linden M, Kakol Z, Sikora M, Haverkort MW, Glatzel P, de Groot FMF. Noncollinear Ordering of the Orbital Magnetic Moments in Magnetite. Phys Rev Lett 2019; 123:207201. [PMID: 31809079 DOI: 10.1103/physrevlett.123.207201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 10/02/2019] [Indexed: 05/22/2023]
Abstract
The magnitude of the orbital magnetic moment and its role as a trigger of the Verwey transition in the prototypical Mott insulator, magnetite, remain contentious. Using 1s2p resonant inelastic x-ray scattering angle distribution (RIXS-AD), we prove the existence of noncollinear orbital magnetic ordering and infer the presence of dynamical distortion creating a polaronic precursor for the metal to insulator transition. These conclusions are based on a subtle angular shift of the RIXS-AD spectral intensity as a function of the magnetic field orientation. Theoretical simulations show that these results are only consistent with noncollinear magnetic orbital ordering. To further support these claims we perform Fe K-edge x-ray magnetic circular dichroism in order to quantify the Fe average orbital magnetic moment.
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Affiliation(s)
- H Elnaggar
- Debye Institute for Nanomaterials Science, Utrecht University, 3584 CA Utrecht, The Netherlands
| | - Ph Sainctavit
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, MNHN, UMR7590, 75252 Paris Cedex 05, France
| | - A Juhin
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, MNHN, UMR7590, 75252 Paris Cedex 05, France
| | - S Lafuerza
- European Synchrotron Radiation Facility, CS40220, F-38043 Grenoble Cedex 9, France
| | - F Wilhelm
- European Synchrotron Radiation Facility, CS40220, F-38043 Grenoble Cedex 9, France
| | - A Rogalev
- European Synchrotron Radiation Facility, CS40220, F-38043 Grenoble Cedex 9, France
| | - M-A Arrio
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, MNHN, UMR7590, 75252 Paris Cedex 05, France
| | - Ch Brouder
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, MNHN, UMR7590, 75252 Paris Cedex 05, France
| | - M van der Linden
- Debye Institute for Nanomaterials Science, Utrecht University, 3584 CA Utrecht, The Netherlands
- European Synchrotron Radiation Facility, CS40220, F-38043 Grenoble Cedex 9, France
| | - Z Kakol
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow, Poland
| | - M Sikora
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow, Poland
| | - M W Haverkort
- Institut für Theoritiche Physik, Universität Heidelberg, Philosophenweg 19, 69120 Heidelberg, Germany
| | - P Glatzel
- European Synchrotron Radiation Facility, CS40220, F-38043 Grenoble Cedex 9, France
| | - F M F de Groot
- Debye Institute for Nanomaterials Science, Utrecht University, 3584 CA Utrecht, The Netherlands
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17
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Soria GD, Jenus P, Marco JF, Mandziak A, Sanchez-Arenillas M, Moutinho F, Prieto JE, Prieto P, Cerdá J, Tejera-Centeno C, Gallego S, Foerster M, Aballe L, Valvidares M, Vasili HB, Pereiro E, Quesada A, de la Figuera J. Strontium hexaferrite platelets: a comprehensive soft X-ray absorption and Mössbauer spectroscopy study. Sci Rep 2019; 9:11777. [PMID: 31409875 PMCID: PMC6692398 DOI: 10.1038/s41598-019-48010-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 07/24/2019] [Indexed: 12/02/2022] Open
Abstract
Platelets of strontium hexaferrite (SrFe12O19, SFO), up to several micrometers in width, and tens of nanometers thick have been synthesized by a hydrothermal method. They have been studied by a combination of structural and magnetic techniques, with emphasis on Mössbauer spectroscopy and X-ray absorption based-measurements including spectroscopy and microscopy on the iron-L edges and the oxygen-K edge, allowing us to establish the differences and similarities between our synthesized nanostructures and commercial powders. The Mössbauer spectra reveal a greater contribution of iron tetrahedral sites in platelets in comparison to pure bulk material. For reference, high-resolution absorption and dichroic spectra have also been measured both from the platelets and from pure bulk material. The O-K edge has been reproduced by density functional theory calculations. Out-of-plane domains were observed with 180° domain walls less than 20 nm width, in good agreement with micromagnetic simulations.
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Affiliation(s)
- G D Soria
- Instituto de Quimica Física "Rocasolano", CSIC, Madrid, E-28006, Spain.
| | - P Jenus
- Institut "Jozef Stefan", Ljubljana, 1000, Slovenia
| | - J F Marco
- Instituto de Quimica Física "Rocasolano", CSIC, Madrid, E-28006, Spain
| | - A Mandziak
- Instituto de Quimica Física "Rocasolano", CSIC, Madrid, E-28006, Spain.,Alba Synchrotron Light Facility, CELLS, Barcelona, E-08290, Spain
| | | | - F Moutinho
- Instituto de Quimica Física "Rocasolano", CSIC, Madrid, E-28006, Spain
| | - J E Prieto
- Instituto de Quimica Física "Rocasolano", CSIC, Madrid, E-28006, Spain
| | - P Prieto
- Universidad Autónoma de Madrid, Madrid, E-28049, Spain
| | - J Cerdá
- Instituto de Ciencias de Materiales de Madrid, CSIC, Madrid, E-28049, Spain
| | - C Tejera-Centeno
- Instituto de Ciencias de Materiales de Madrid, CSIC, Madrid, E-28049, Spain
| | - S Gallego
- Instituto de Ciencias de Materiales de Madrid, CSIC, Madrid, E-28049, Spain
| | - M Foerster
- Alba Synchrotron Light Facility, CELLS, Barcelona, E-08290, Spain
| | - L Aballe
- Alba Synchrotron Light Facility, CELLS, Barcelona, E-08290, Spain
| | - M Valvidares
- Alba Synchrotron Light Facility, CELLS, Barcelona, E-08290, Spain
| | - H B Vasili
- Alba Synchrotron Light Facility, CELLS, Barcelona, E-08290, Spain
| | - E Pereiro
- Alba Synchrotron Light Facility, CELLS, Barcelona, E-08290, Spain
| | - A Quesada
- Instituto de Cerámica y Vidrio, CSIC, Madrid, E-28049, Spain
| | - J de la Figuera
- Instituto de Quimica Física "Rocasolano", CSIC, Madrid, E-28006, Spain
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18
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19
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Hamed MH, Hinz RA, Lömker P, Wilhelm M, Gloskovskii A, Bencok P, Schmitz-Antoniak C, Elnaggar H, Schneider CM, Müller M. Tunable Magnetic Phases at Fe 3O 4/SrTiO 3 Oxide Interfaces. ACS Appl Mater Interfaces 2019; 11:7576-7583. [PMID: 30672270 DOI: 10.1021/acsami.8b20625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We demonstrate the emergence and control of magnetic phases between magnetite (Fe3O4), a ferrimagnetic halfmetal, and SrTiO3, a transparent nonmagnetic insulator considered the bedrock of oxide-based electronics. The Verwey transition ( TV) was detected to persist from bulk-like down to ultrathin Fe3O4 films, decreasing from 117 ± 4 K (38 nm) to 25 ± 4 K (2 nm), respectively. Element-selective electronic and magnetic properties of the ultrathin films and buried interfaces are studied by angle-dependent hard X-ray photoelectron spectroscopy and X-ray magnetic circular dichroism techniques. We observe a reduction of Fe2+ ions with decreasing film thickness, accompanied by an increase of Fe3+ ions in both tetrahedral and octahedral sites and conclude on the formation of a magnetically active ferrimagnetic 2 u.c. γ-Fe2O3 intralayer. To manipulate the interfacial magnetic phase, a postannealing process causes the controlled reduction of the γ-Fe2O3 that finally leads to stoichiometric and ferrimagnetic Fe3O4/SrTiO3(001) heterointerfaces.
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Affiliation(s)
- Mai Hussein Hamed
- Peter-Grünberg-Institut (PGI-6) , Forschungszentrum Jülich GmbH , 52425 Jülich , Germany
- Faculty of Science , Helwan University , 11795 Cairo , Egypt
| | - Ronja Anika Hinz
- Peter-Grünberg-Institut (PGI-6) , Forschungszentrum Jülich GmbH , 52425 Jülich , Germany
| | - Patrick Lömker
- Peter-Grünberg-Institut (PGI-6) , Forschungszentrum Jülich GmbH , 52425 Jülich , Germany
| | - Marek Wilhelm
- Peter-Grünberg-Institut (PGI-6) , Forschungszentrum Jülich GmbH , 52425 Jülich , Germany
| | - Andrei Gloskovskii
- Photon Science, Deutsches Elektronen-Synchrotron DESY , 22607 Hamburg , Germany
| | | | | | - Hebatalla Elnaggar
- Debye Institute for Nanomaterials Science , 3584 CG Utrecht , The Netherlands
| | - Claus M Schneider
- Peter-Grünberg-Institut (PGI-6) , Forschungszentrum Jülich GmbH , 52425 Jülich , Germany
- Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CeNIDE) , 47048 Duisburg , Germany
| | - Martina Müller
- Peter-Grünberg-Institut (PGI-6) , Forschungszentrum Jülich GmbH , 52425 Jülich , Germany
- Experimentelle Physik I , Technische Universität Dortmund , 44227 Dortmund , Germany
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20
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Mandziak A, de la Figuera J, Ruiz-Gómez S, Soria GD, Pérez L, Prieto P, Quesada A, Foerster M, Aballe L. Structure and magnetism of ultrathin nickel-iron oxides grown on Ru(0001) by high-temperature oxygen-assisted molecular beam epitaxy. Sci Rep 2018; 8:17980. [PMID: 30568169 PMCID: PMC6299276 DOI: 10.1038/s41598-018-36356-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 11/15/2018] [Indexed: 11/10/2022] Open
Abstract
We demonstrate the preparation of ultrathin Fe-rich nickel ferrite (NFO) islands on a metal substrate. Their nucleation and growth are followed in situ by low-energy electron microscopy (LEEM). A comprehensive characterization is performed combining LEEM for structural characterization and PEEM (PhotoEmission Electron Microscopy) with synchrotron radiation for chemical and magnetic analysis via X-ray Absorption Spectroscopy and X-ray Magnetic Circular Dichroism (XAS-PEEM and XMCD-PEEM, respectively). The growth by oxygen-assisted molecular beam epitaxy takes place in two stages. First, islands with the rocksalt structure nucleate and grow until they completely cover the substrate surface. Later three-dimensional islands of spinel phase grow on top of the wetting layer. Only the spinel islands show ferromagnetic contrast, with the same domains being observed in the Fe and Ni XMCD images. The estimated magnetic moments of Fe and Ni close to the islands surface indicate a possible role of the bi-phase reconstruction. A significant out-of-plane magnetization component was detected by means of XMCD-PEEM vector maps.
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Affiliation(s)
- Anna Mandziak
- Instituto de Química Física "Rocasolano", Madrid, E-28006, Spain.,Alba Synchrotron Light Facility, CELLS, Barcelona, E-08290, Spain
| | | | - Sandra Ruiz-Gómez
- Dpto. de Física de Materiales, Universidad Complutense de Madrid, Madrid, E-28040, Spain.,Unidad Asociada UCM-IQFR(CSIC), Madrid, E-28006, Spain
| | - Guiomar D Soria
- Instituto de Química Física "Rocasolano", Madrid, E-28006, Spain
| | - Lucas Pérez
- Dpto. de Física de Materiales, Universidad Complutense de Madrid, Madrid, E-28040, Spain.,Unidad Asociada UCM-IQFR(CSIC), Madrid, E-28006, Spain.,Instituto Madrileño de Estudios Avanzados - IMDEA Nanociencia, Madrid, E-28099, Spain
| | - Pilar Prieto
- Dpto. de Física Aplicada, Universidad Autónoma de Madrid, Madrid, E-28049, Spain
| | - Adrian Quesada
- Instituto de Cerámica y Vidrio (CSIC), Madrid, E-28049, Spain
| | - Michael Foerster
- Alba Synchrotron Light Facility, CELLS, Barcelona, E-08290, Spain
| | - Lucía Aballe
- Alba Synchrotron Light Facility, CELLS, Barcelona, E-08290, Spain
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21
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Zhong G, An F, Bitla Y, Wang J, Zhong X, Yu J, Gao W, Zhang Y, Tan C, Ou Y, Jiang J, Hsieh YH, Pan X, Xie S, Chu YH, Li J. Deterministic, Reversible, and Nonvolatile Low-Voltage Writing of Magnetic Domains in Epitaxial BaTiO 3/Fe 3O 4 Heterostructure. ACS Nano 2018; 12:9558-9567. [PMID: 30138564 DOI: 10.1021/acsnano.8b05284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The ability to electrically write magnetic bits is highly desirable for future magnetic memories and spintronic devices, though fully deterministic, reversible, and nonvolatile switching of magnetic moments by electric field remains elusive despite extensive research. In this work, we develop a concept to electrically switch magnetization via polarization modulated oxygen vacancies, and we demonstrate the idea in a multiferroic epitaxial heterostructure of BaTiO3/Fe3O4 fabricated by pulsed laser deposition. The piezoelectricity and ferroelectricity of BaTiO3 have been confirmed by macro- and microscale measurements, for which Fe3O4 serves as the top electrode for switching the polarization. X-ray absorption spectroscopy and X-ray magnetic circular dichroism spectra indicate a mixture of Fe2+ and Fe3+ at O h sites and Fe3+ at T d sites in Fe3O4, while the room-temperature magnetic domains of Fe3O4 are revealed by microscopic magnetic force microscopy measurements. It is demonstrated that the magnetic domains of Fe3O4 can be switched by not only magnetic fields but also electric fields in a deterministic, reversible, and nonvolatile manner, wherein polarization reversal by electric field modulates the oxygen vacancy distribution in Fe3O4, and thus its magnetic state, making it attractive for electrically written magnetic memories.
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Affiliation(s)
- Gaokuo Zhong
- Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , Guangdong , China
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
- Department of Materials Science and Engineering , National Chiao Tung University , Hsinchu 30010 , Taiwan
- Department of Chemical Engineering and Materials Science , University of California, Irvine , Irvine 92697 , California , United States
| | - Feng An
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Yugandhar Bitla
- Department of Physics , Indian Institute of Science , Bengaluru 560012 , India
| | - Jinbin Wang
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Xiangli Zhong
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Junxi Yu
- Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , Guangdong , China
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Wenpei Gao
- Department of Chemical Engineering and Materials Science , University of California, Irvine , Irvine 92697 , California , United States
| | - Yi Zhang
- Department of Chemical Engineering and Materials Science , University of California, Irvine , Irvine 92697 , California , United States
| | - Congbing Tan
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Yun Ou
- Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , Guangdong , China
| | - Jie Jiang
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Ying-Hui Hsieh
- Department of Materials Science and Engineering , National Chiao Tung University , Hsinchu 30010 , Taiwan
| | - Xiaoqing Pan
- Department of Chemical Engineering and Materials Science , University of California, Irvine , Irvine 92697 , California , United States
| | - Shuhong Xie
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Ying-Hao Chu
- Department of Materials Science and Engineering , National Chiao Tung University , Hsinchu 30010 , Taiwan
| | - Jiangyu Li
- Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , Guangdong , China
- Department of Mechanical Engineering , University of Washington , Seattle 98195 , Washington , United States
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22
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Chesnel K, Griner D, Smith D, Cai Y, Trevino M, Newbold B, Wang T, Liu T, Jal E, Reid A, Harrison R. Unraveling Nanoscale Magnetic Ordering in Fe3O4 Nanoparticle Assemblies via X-rays. Magnetochemistry 2018; 4:42. [DOI: 10.3390/magnetochemistry4040042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Understanding the correlations between magnetic nanoparticles is important for nanotechnologies, such as high-density magnetic recording and biomedical applications, where functionalized magnetic particles are used as contrast agents and for drug delivery. The ability to control the magnetic state of individual particles depends on the good knowledge of the magnetic correlations between particles when assembled. Inaccessible via standard magnetometry techniques, nanoscale magnetic ordering in self-assemblies of Fe3O4 nanoparticles is here unveiled via X-ray resonant magnetic scattering (XRMS). Measured throughout the magnetization process, the XRMS signal reveals size-dependent inter-particle magnetic correlations. Smaller (5 nm) particles show little magnetic correlations, even when packed close together, yielding to magnetic disorder in the absence of an external field, i.e., superparamagnetism. In contrast, larger (11 nm) particles tend to be more strongly correlated, yielding a mix of magnetic orders including ferromagnetic and anti-ferromagnetic orders. These magnetic correlations are present even when the particles are sparsely distributed.
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23
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Castán-Guerrero C, Krizmancic D, Bonanni V, Edla R, Deluisa A, Salvador F, Rossi G, Panaccione G, Torelli P. A reaction cell for ambient pressure soft x-ray absorption spectroscopy. Rev Sci Instrum 2018; 89:054101. [PMID: 29864817 DOI: 10.1063/1.5019333] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We present a new experimental setup for performing X-ray Absorption Spectroscopy (XAS) in the soft X-ray range at ambient pressure. The ambient pressure XAS setup is fully compatible with the ultra high vacuum environment of a synchrotron radiation spectroscopy beamline end station by means of ultrathin Si3N4 membranes acting as windows for the X-ray beam and seal of the atmospheric sample environment. The XAS detection is performed in total electron yield (TEY) mode by probing the drain current from the sample with a picoammeter. The high signal/noise ratio achievable in the TEY mode, combined with a continuous scanning of the X-ray energies, makes it possible recording XAS spectra in a few seconds. The first results show the performance of this setup to record fast XAS spectra from sample surfaces exposed at atmospheric pressure, even in the case of highly insulating samples. The use of a permanent magnet inside the reaction cell enables the measurement of X-ray magnetic circular dichroism at ambient pressure.
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Affiliation(s)
- C Castán-Guerrero
- Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza 34149, Trieste, Italy
| | - D Krizmancic
- Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza 34149, Trieste, Italy
| | - V Bonanni
- Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza 34149, Trieste, Italy
| | - R Edla
- Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza 34149, Trieste, Italy
| | - A Deluisa
- Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza 34149, Trieste, Italy
| | - F Salvador
- Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza 34149, Trieste, Italy
| | - G Rossi
- Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza 34149, Trieste, Italy
| | - G Panaccione
- Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza 34149, Trieste, Italy
| | - P Torelli
- Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza 34149, Trieste, Italy
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24
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Goroncy C, Saloga PEJ, Gruner M, Schmudde M, Vonnemann J, Otero E, Haag R, Graf C. Influence of Organic Ligands on the Surface Oxidation State and Magnetic Properties of Iron Oxide Particles. Z PHYS CHEM 2018; 232:819-44. [DOI: 10.1515/zpch-2017-1084] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
For the application of iron oxide nanoparticles from thermal decomposition approaches as contrast agents in magnetic resonance imaging (MRI), their initial hydrophobic ligands have to be replaced by hydrophilic ones. This exchange can influence the surface oxidation state and the magnetic properties of the particles. Here, the effect of the anchor group of three organic ligands, citric acid and two catechols, dihydrocaffeic acid and its nitrated derivative nitro dihydrocaffeic acid on iron oxide nanoparticles is evaluated. The oleate ligands of Fe3O4/γ-Fe2O3 nanoparticles prepared by the thermal decomposition of iron oleate were exchanged against the hydrophilic ligands. X-ray absorption spectroscopy, especially X-ray magnetic circular dichroism (XMCD) measurements in the total electron yield (TEY) mode was used to investigate local magnetic and electronic properties of the particles’ surface region before and after the ligand exchange. XMCD was combined with charge transfer multiplet calculations which provide information on the contributions of Fe2+ and Fe3+ at different lattice sites, i.e. either in tetrahedral or octahedral environment. The obtained data demonstrate that nitro hydrocaffeic acid leads to least reduction of the magnetizability of the surface region of the iron oxide nanoparticles compared to the two other ligands. For all hydrophilic samples, the proportion of Fe3+ ions in octahedral sites increases at the expense of the Fe2+ in octahedral sites whereas the percentage of Fe3+ in tetrahedral sites hardly changes. These observations suggest that an oxidation process took place, but a selective decrease of the Fe2+ ions in octahedral sites ions due to surface dissolution processes is unlikely. The citrate ligand has the least oxidative effect, whereas the degree of oxidation was similar for both catechol ligands regardless of the nitro group. Twenty-four hours of incubation in isotonic saline has nearly no influences on the magnetic properties of the nanoparticles, the least on those with the nitrated hydrocaffeic acid ligand.
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25
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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26
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Cao L, Jiang ZX, Du YH, Yin XM, Xi SB, Wen W, Roberts AP, Wee ATS, Xiong YM, Liu QS, Gao XY. Origin of Magnetism in Hydrothermally Aged 2-Line Ferrihydrite Suspensions. Environ Sci Technol 2017; 51:2643-2651. [PMID: 28125227 DOI: 10.1021/acs.est.6b04716] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
As an iron oxyhydroxide, nanosized ferrihydrite (Fh) is important in Earth science, biology, and industrial applications. However, its basic structure and origin of its magnetism have long been debated. We integrate synchrotron-based techniques to explore the chemical structures of 2-line ferrihydrite and to determine the origin of its magnetism during hydrothermal aging in air. Our results demonstrate that both the magnetism and X-ray magnetic circular dichroism (XMCD) signal of 2-line ferrihydrite are enhanced with aging time, and that XMCD spectral patterns resemble that of maghemite (γ-Fe2O3) rather than magnetite (Fe3O4). Fe L-edge and K-edge X-ray absorption spectroscopy (XAS) further indicate formation of both maghemite and hematite (α-Fe2O3) with increasing concentrations with longer hydrothermal aging time. Thus, magnetic enhancement with longer hydrothermal aging time is attributed to increasing maghemite concentration instead of a magnetically ordered ferrihydrite as previously reported. Moreover, L-edge and K-edge XAS spectra with different probing depths yield different ratios of these Fe oxides, which suggest the formation of a core (ferrihydrite-rich)-shell (with a mixture of both allotropes; α-Fe2O3 and γ-Fe2O3) structure during hydrothermal aging. Our results provide insights into the chemical evolution of 2-line ferrihydrite that reveal unambiguously the origin of its magnetism.
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Affiliation(s)
- Liang Cao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences , P.O. Box 800-204, Shanghai, 201800, P. R. China
- High Magnetic Field Laboratory, Chinese Academy of Sciences , 350 Shushanhu Road, Hefei, Anhui, 230031, P. R. China
| | - Zhao-Xia Jiang
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences , 19 Beitucheng Western Road, Beijing, 100029, P. R. China
| | - Yong-Hua Du
- Institute of Chemical and Engineering Sciences , A*STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, 627833, Singapore
| | - Xin-Mao Yin
- Department of Physics, National University of Singapore , 2 Science Drive 3, 117542, Singapore
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University , Shenzhen, 518060, P. R. China
| | - Shi-Bo Xi
- Institute of Chemical and Engineering Sciences , A*STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, 627833, Singapore
| | - Wen Wen
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences , P.O. Box 800-204, Shanghai, 201800, P. R. China
| | - Andrew P Roberts
- Research School of Earth Sciences, The Australian National University , 142 Mills Road, Canberra, ACT 2601, Australia
| | - Andrew T S Wee
- Department of Physics, National University of Singapore , 2 Science Drive 3, 117542, Singapore
| | - Yi-Min Xiong
- High Magnetic Field Laboratory, Chinese Academy of Sciences , 350 Shushanhu Road, Hefei, Anhui, 230031, P. R. China
| | - Qing-Song Liu
- Department of Marine Science and Engineering, Southern University of Science and Technology of China , Shenzhen, 518055, P. R. China
- Laboratory for Marine Geology, Qingdao National Oceanography Laboratory for Science and Technology , Qingdao, 266071, P. R. China
| | - Xing-Yu Gao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences , P.O. Box 800-204, Shanghai, 201800, P. R. China
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27
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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28
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Guo D, An Y, Cui W, Zhi Y, Zhao X, Lei M, Li L, Li P, Wu Z, Tang W. Epitaxial growth and magnetic properties of ultraviolet transparent Ga2O3/(Ga1-xFex)2O3 multilayer thin films. Sci Rep 2016; 6:25166. [PMID: 27121446 PMCID: PMC4848556 DOI: 10.1038/srep25166] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 04/11/2016] [Indexed: 11/09/2022] Open
Abstract
Multilayer thin films based on the ferromagnetic and ultraviolet transparent semiconductors may be interesting because their magnetic/electronic/photonic properties can be manipulated by the high energy photons. Herein, the Ga2O3/(Ga1-xFex)2O3 multilayer epitaxial thin films were obtained by alternating depositing of wide band gap Ga2O3 layer and Fe ultrathin layer due to inter diffusion between two layers at high temperature using the laser molecular beam epitaxy technique. The multilayer films exhibits a preferred growth orientation of crystal plane, and the crystal lattice expands as Fe replaces Ga site. Fe ions with a mixed valence of Fe(2+) and Fe(3+) are stratified distributed in the film and exhibit obvious agglomerated areas. The multilayer films only show a sharp absorption edge at about 250 nm, indicating a high transparency for ultraviolet light. What's more, the Ga2O3/(Ga1-xFex)2O3 multilayer epitaxial thin films also exhibits room temperature ferromagnetism deriving from the Fe doping Ga2O3.
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Affiliation(s)
- Daoyou Guo
- Laboratory of Optoelectronics Materials and Devices, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.,State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China.,Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Yuehua An
- Laboratory of Optoelectronics Materials and Devices, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.,State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Wei Cui
- Laboratory of Optoelectronics Materials and Devices, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.,State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Yusong Zhi
- Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Xiaolong Zhao
- Laboratory of Optoelectronics Materials and Devices, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.,State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Ming Lei
- Laboratory of Optoelectronics Materials and Devices, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.,State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Linghong Li
- Department of Physics, The State University of New York at Potsdam, Potsdam, New York 13676-2294, USA
| | - Peigang Li
- Laboratory of Optoelectronics Materials and Devices, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.,Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Zhenping Wu
- Laboratory of Optoelectronics Materials and Devices, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.,State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Weihua Tang
- Laboratory of Optoelectronics Materials and Devices, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.,State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
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29
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Dimitrakis DA, Tsongidis NI, Konstandopoulos AG. Reduction enthalpy and charge distribution of substituted ferrites and doped ceria for thermochemical water and carbon dioxide splitting with DFT+U. Phys Chem Chem Phys 2016; 18:23587-95. [DOI: 10.1039/c6cp05073e] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Effect of Nickel ions on reduction energy and charge distribution of oxygen – neighbouring ions in NiFe2O4 for solar fuels.
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Affiliation(s)
- D. A. Dimitrakis
- Aerosol & Particle Technology Laboratory
- CPERI/CERTH
- 57001 Thessaloniki
- Greece
- Department of Chemical Engineering
| | - N. I. Tsongidis
- Aerosol & Particle Technology Laboratory
- CPERI/CERTH
- 57001 Thessaloniki
- Greece
- Department of Chemical Engineering
| | - A. G. Konstandopoulos
- Aerosol & Particle Technology Laboratory
- CPERI/CERTH
- 57001 Thessaloniki
- Greece
- Department of Chemical Engineering
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30
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Lee MC, Sohn CH, Kim SY, Lee KD, Won CJ, Hur N, Kim JY, Cho DY, Noh TW. Stabilization of ferromagnetic ordering in cobaltite double perovskites of La₂CoIrO₆ and La₂CoPtO₆. J Phys Condens Matter 2015; 27:336002. [PMID: 26235708 DOI: 10.1088/0953-8984/27/33/336002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigated the local electronic structure and magnetic properties of the cobaltite double perovskites La2CoIrO6 and La2CoPtO6 using Co L2,3-edge x-ray absorption spectroscopy and x-ray magnetic circular dichroism. Despite similarity in the local electronic structure (Co(2+) high-spin states) as well as in the crystal structure (P2(1)/n), only La2CoIrO6 exhibits substantial orbital and spin magnetic moments of Co(2+), whereas they are much weaker in the case of La2CoPtO6. This composition dependence is consistent with the results of magnetization measurements. The details of the mechanism of ferromagnetic ordering in the Co(2+) sublattice in La2CoIrO6 and the lack thereof in La2CoPtO6 are explained in terms of the orbital hybridization of the Co minority-spin t(2g) state and the Ir/Pt j(eff) = 1/2 state.
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Affiliation(s)
- Min-Cheol Lee
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul National University, Seoul 151-742, Korea. Department of Physics and Astronomy, Seoul National University (SNU), Seoul 151-742, Korea
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31
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Thersleff T, Rusz J, Rubino S, Hjörvarsson B, Ito Y, J. Zaluzec N, Leifer K. Quantitative analysis of magnetic spin and orbital moments from an oxidized iron (1 1 0) surface using electron magnetic circular dichroism. Sci Rep 2015; 5:13012. [PMID: 26278134 PMCID: PMC4538391 DOI: 10.1038/srep13012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 07/03/2015] [Indexed: 11/17/2022] Open
Abstract
Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magnetic orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features.
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Affiliation(s)
- Thomas Thersleff
- Department of Engineering Sciences, Division of Applied Materials, Uppsala University, Uppsala, Sweden
| | - Jan Rusz
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Stefano Rubino
- Department of Engineering Sciences, Division of Applied Materials, Uppsala University, Uppsala, Sweden
- Department of Physics, University of Oslo, Oslo, Norway
| | | | - Yasuo Ito
- Department of Physics, Northern Illinois University, DeKalb, IL, USA
| | - Nestor J. Zaluzec
- Electron Microscopy Center, NanoScience and Technology Division, Argonne National Laboratory, Argonne, IL, USA
| | - Klaus Leifer
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
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32
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Abstract
Magnetite (Fe3O4) shows singular electronic and magnetic properties, resulting from complex electron-electron and electron-phonon interactions that involve the interplay of charge, orbital and spin degrees of freedom. The Verwey transition is a manifestation of these interactions, with a puzzling connection between the low temperature charge ordered state and the dynamic charge fluctuations still present above the transition temperature. Here we explore how these rich physical phenomena are affected by thin film geometries, particularly focusing on the ultimate size limit defined by thicknesses below the minimum bulk unit cell. On one hand, we address the influence of extended defects, such as surfaces or antiphase domains, on the novel features exhibited by thin films. On the other, we try to isolate the effect of the reduced thickness on the electronic and magnetic properties. We will show that a distinct phase diagram and novel charge distributions emerge under reduced dimensions, while holding the local high magnetic moments. Altogether, thin film geometries offer unique possibilities to understand the complex interplay of short- and long-range orders in the Verwey transition. Furthermore, they arise as interesting candidates for the exploitation of the rich physics of magnetite in devices that demand nanoscale geometries, additionally offering novel functionalities based on their distinct properties with respect to the bulk form.
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Affiliation(s)
- I Bernal-Villamil
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid, Spain
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33
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Yun H, Liu X, Paik T, Palanisamy D, Kim J, Vogel WD, Viescas AJ, Chen J, Papaefthymiou GC, Kikkawa JM, Allen MG, Murray CB. Size- and composition-dependent radio frequency magnetic permeability of iron oxide nanocrystals. ACS Nano 2014; 8:12323-12337. [PMID: 25390073 DOI: 10.1021/nn504711g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigate the size- and composition-dependent ac magnetic permeability of superparamagnetic iron oxide nanocrystals for radio frequency (RF) applications. The nanocrystals are obtained through high-temperature decomposition synthesis, and their stoichiometry is determined by Mössbauer spectroscopy. Two sets of oxides are studied: (a) as-synthesized magnetite-rich and (b) aged maghemite nanocrystals. All nanocrystalline samples are confirmed to be in the superparamagnetic state at room temperature by SQUID magnetometry. Through the one-turn inductor method, the ac magnetic properties of the nanocrystalline oxides are characterized. In magnetite-rich iron oxide nanocrystals, size-dependent magnetic permeability is not observed, while maghemite iron oxide nanocrystals show clear size dependence. The inductance, resistance, and quality factor of hand-wound inductors with a superparamagnetic composite core are measured. The superparamagnetic nanocrystals are successfully embedded into hand-wound inductors to function as inductor cores.
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Affiliation(s)
- Hongseok Yun
- Department of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical and Systems Engineering, and ⊥Department of Physics and Astronomy, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
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34
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Abstract
Worldwide research activity at the nanoscale is triggering the appearance of new, and frequently surprising, materials properties in which the increasing importance of surface and interface effects plays a fundamental role. This opens further possibilities in the development of new multifunctional materials with tuned physical properties that do not arise together at the bulk scale. Unfortunately, the standard methods currently available for solving the atomic structure of bulk crystals fail for nanomaterials due to nanoscale effects (very small crystallite sizes, large surface-to-volume ratio, near-surface relaxation, local lattice distortions etc.). As a consequence, a critical reexamination of the available local-structure characterization methods is needed. This work discusses the real possibilities and limits of X-ray absorption spectroscopy (XAS) analysis at the nanoscale. To this end, the present state of the art for the interpretation of extended X-ray absorption fine structure (EXAFS) is described, including an advanced approach based on the use of classical molecular dynamics and its application to nickel oxide nanoparticles. The limits and possibilities of X-ray absorption near-edge spectroscopy (XANES) to determine several effects associated with the nanocrystalline nature of materials are discussed in connection with the development of ZnO-based dilute magnetic semiconductors (DMSs) and iron oxide nanoparticles.
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Affiliation(s)
- Alexei Kuzmin
- Institute of Solid State Physics, University of Latvia, LV-1063 Riga, Latvia
| | - Jesús Chaboy
- Instituto de Ciencia de Materiales de Aragón, Consejo Superior de Investigaciones Científicas and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain
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35
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Vaz CAF, Balan A, Nolting F, Kleibert A. In situ magnetic and electronic investigation of the early stage oxidation of Fe nanoparticles using X-ray photo-emission electron microscopy. Phys Chem Chem Phys 2014; 16:26624-30. [DOI: 10.1039/c4cp02725f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In situX-ray photoemission electron microscopy reveals the evolution of chemical composition and magnetism of individual iron nanoparticles during oxidation.
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Affiliation(s)
- C. A. F. Vaz
- Swiss Light Source
- Paul Scherrer Institut
- 5232 Villigen PSI, Switzerland
| | - A. Balan
- Swiss Light Source
- Paul Scherrer Institut
- 5232 Villigen PSI, Switzerland
| | - F. Nolting
- Swiss Light Source
- Paul Scherrer Institut
- 5232 Villigen PSI, Switzerland
| | - A. Kleibert
- Swiss Light Source
- Paul Scherrer Institut
- 5232 Villigen PSI, Switzerland
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36
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37
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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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38
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Andersson DA, Stanek CR. Mixing and non-stoichiometry in Fe–Ni–Cr–Zn–O spinel compounds: density functional theory calculations. Phys Chem Chem Phys 2013; 15:15550-64. [DOI: 10.1039/c3cp50312g] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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39
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Zhao Q, Wen G, Liu Z, Fan Y, Zou G, Li L, Zheng R, Ringer SP, Mao HK. Synthesis of dense, single-crystalline CrO2 nanowire arrays using AAO template-assisted chemical vapor deposition. Nanotechnology 2011; 22:125603. [PMID: 21325713 DOI: 10.1088/0957-4484/22/12/125603] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
High-density, vertically aligned CrO(2) nanowire arrays were obtained via atmospheric-pressure CVD assisted by AAO templates. The CrO(2) nanowire arrays show remarkably enhanced coercivity compared with CrO(2) films or bulk. It was found that the length of the nanowires is greatly influenced by the pore diameter of the AAO template used. The growth mechanism and the pore size dependence of the CrO(2) nanowire arrays are discussed. The present method provides a useful approach for the synthesis of CrO(2) nanowire arrays. Such highly ordered nanowire arrays within an AAO template may have important applications in ultrahigh-density perpendicular magnetic recording devices and the mass production of spintronic nanodevices.
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Affiliation(s)
- Qiang Zhao
- State Key Laboratory of Superhard Materials, Jilin University, Changchun, People's Republic of China
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40
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Sikora M, Juhin A, Weng TC, Sainctavit P, Detlefs C, de Groot F, Glatzel P. Strong K-edge magnetic circular dichroism observed in photon-in-photon-out spectroscopy. Phys Rev Lett 2010; 105:037202. [PMID: 20867798 DOI: 10.1103/physrevlett.105.037202] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2010] [Indexed: 05/20/2023]
Abstract
A large enhancement of the x-ray magnetic circular dichroism is observed at the iron K absorption preedge of magnetite. This is achieved by performing resonant inelastic x-ray scattering (RIXS) experiments with a 2p hole in the final state of the second-order optical process. We measured and calculated the full 1s2p RIXS planes for opposite helicities of the incoming circularly polarized x rays. The crystal field multiplet calculations show that the enhancement arises from 2p-3d Coulomb repulsions and 2p and 3d spin-orbit coupling. The observed magnitude of the RIXS magnetic circular dichroism effect is ∼16%. This opens up new opportunities for a broad range of research fields allowing for truly bulk-sensitive, element-, and site-selective measurements of 3d transition metal magnetic moments and their ordering using hard x-ray photons.
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Affiliation(s)
- Marcin Sikora
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Kraków, Poland.
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41
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Abstract
In this viewpoint article we analyse recent crucial structural, optical and transport experiments on Fe(3)O(4) magnetite across the Verwey transition at T(V)∼120-125 K. We find that all the relevant experimental data are consistent with a model of a Peierls distortion in the cubic spinel lattice, and likewise, some of them evidence against the original and still distributed hypothesis of the long range charge ordering origin of the Verwey transition. An estimated Peierls transition temperature (T(P)) is comparable with T(V). The Peierls model provides new insight into the electronic properties of magnetite. Application of the Peierls model to some other systems is briefly discussed also.
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Affiliation(s)
- Vladimir V Shchennikov
- High Pressure Group, Institute of Metal Physics, Russian Academy of Sciences, Urals Division, GSP-170, 18 S Kovalevskaya Street, Yekaterinburg 620041, Russia
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43
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Pinto HP, Elliott SD. Mechanism of the Verwey transition in magnetite: Jahn-Teller distortion and charge ordering patterns. J Phys Condens Matter 2006; 18:10427-10436. [PMID: 21690927 DOI: 10.1088/0953-8984/18/46/010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have performed density functional calculations with on-site Coulomb repulsion corrections of systems that may be involved in the Verwey transition in magnetite (Fe(3)O(4)). We find that the lowest energy solution for the minority spin wavefunction in the cubic cell involves orbitally ordered Fe-d and O-p states, which breaks cubic symmetry. This leads to partial charge ordering that triggers a Jahn-Teller distortion and band-gap opening. Our results show this to be the essential mechanism of the Verwey transition. Applying ionic relaxation within a larger tetragonal cell, three patterns of charge ordering are compared and a Pmca pattern matching x-ray data is found to be the most stable.
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Affiliation(s)
- H P Pinto
- Tyndall National Institute, Lee Maltings, Cork, Republic of Ireland
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44
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Hemberger J, Rudolf T, Krug von Nidda HA, Mayr F, Pimenov A, Tsurkan V, Loidl A. Spin-driven phonon splitting in bond-frustrated ZnCr2S4. Phys Rev Lett 2006; 97:087204. [PMID: 17026329 DOI: 10.1103/physrevlett.97.087204] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Indexed: 05/12/2023]
Abstract
Magnetic susceptibility, specific heat, thermal expansion, and IR spectroscopy provide experimental evidence that the two subsequent antiferromagnetic transitions in ZnCr2S4 at TN1 = 15 K and TN2 = 8 K are accompanied by significant thermal and phonon anomalies. The anomaly at TN2 reveals a temperature hysteresis typical for a first-order transformation. Because of strong spin-phonon coupling, both magnetic transitions at TN1 and TN2 induce a splitting of phonon modes. The anomalies and phonon splitting observed at TN2 are suppressed by strong magnetic field. Regarding the small positive Curie-Weiss temperature Theta approximately 8 K, we argue that this scenario of two different magnetic phases with different magnetoelastic couplings results from the strong competition of ferromagnetic and antiferromagnetic exchange.
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Affiliation(s)
- J Hemberger
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86159 Augsburg, Germany
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45
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Goering E, Lafkioti M, Gold S. Comment on "spin and orbital magnetic moments of Fe3O4". Phys Rev Lett 2006; 96:039701; discussion 039702. [PMID: 16486788 DOI: 10.1103/physrevlett.96.039701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Indexed: 05/06/2023]
Affiliation(s)
- E Goering
- Max-Planck-Institute for Metal Research Heisenbergstrasse 3 70569 Stuttgart, Germany
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