1
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Ding X, Cui X, Tseng LT, Wang Y, Qu J, Yue Z, Sang L, Lee WT, Guan X, Bao N, Sathish CI, Yu X, Xi S, Breese MBH, Zheng R, Wang X, Wang L, Wu T, Ding J, Vinu A, Ringer SP, Yi J. Realization of High Magnetization in Artificially Designed Ni/NiO Layers through Exchange Coupling. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2304369. [PMID: 37715070 DOI: 10.1002/smll.202304369] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 08/23/2023] [Indexed: 09/17/2023]
Abstract
High-magnetization materials play crucial roles in various applications. However, the past few decades have witnessed a stagnation in the discovery of new materials with high magnetization. In this work, Ni/NiO nanocomposites are fabricated by depositing Ni and NiO thin layers alternately, followed by annealing at specific temperatures. Both the as-deposited samples and those annealed at 373 K exhibit low magnetization. However, the samples annealed at 473 K exhibit a significantly enhanced saturation magnetization exceeding 607 emu cm-3 at room temperature, surpassing that of pure Ni (480 emu cm-3). Material characterizations indicate that the composite comprises NiO nanoclusters of size 1-2 nm embedded in the Ni matrix. This nanoclustered NiO is primarily responsible for the high magnetization, as confirmed by density functional theory calculations. The calculations also indicate that the NiO clusters are ferromagnetically coupled with Ni, resulting in enhanced magnetization. This work demonstrates a new route toward developing artificial high-magnetization materials using the high magnetic moments of nanoclustered antiferromagnetic materials.
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Affiliation(s)
- Xiang Ding
- School of Transportation and Logistics Engineering, Wuhan University of Technology, Wuhan, 430063, China
| | - Xiangyuan Cui
- School of Aerospace Mechanical & Mechatronic Engineering and Australian Centre for Microscopy & Microanalysis, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Li-Ting Tseng
- School of Materials Science and Engineering, UNSW, Sydney, NSW, 2052, Australia
| | - Yiren Wang
- School of Materials Science and Engineering, Central South University, Changsha, 410083, P. R. China
| | - Jiangtao Qu
- School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Zengji Yue
- Institute of Photonic Chips, University of Shanghai for Science and Technology, Shanghai, 200093, P. R. China
| | - Lina Sang
- School of Integrated Circuit Science and Engineering, Tianjin Key Laboratory of Film Electronic & Communication Devices, Tianjin University of Technology, Tianjin, 300384, P. R. China
| | - Wai Tung Lee
- Science Directorate, European Spallation Source Partikelgatan 2, Lund, 224 84, Sweden
| | - Xinwei Guan
- Global Innovative Center for Advanced Nanomaterials, School of Engineering, University of Newcastle, Callaghan, NSW, 2308, Australia
| | - Nina Bao
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 1192690
| | - C I Sathish
- Global Innovative Center for Advanced Nanomaterials, School of Engineering, University of Newcastle, Callaghan, NSW, 2308, Australia
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore, Singapore, 119260
| | - Shibo Xi
- Institute of Chemical and Engineering Science, Agency for Science, Technology and Research (A*STAR), 1 Pesek Road, Jurong Island, Singapore, 627833
| | - Mark B H Breese
- Singapore Synchrotron Light Source, National University of Singapore, Singapore, 119260
| | - Rongkun Zheng
- School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Xiaolin Wang
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, NSW, 2500, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), University of Wollongong, Wollongong, NSW, 2500, Australia
| | - Lan Wang
- School of Physics, Hefei University of Technology, Hefei, 230009, P. R. China
| | - Tom Wu
- School of Materials Science and Engineering, UNSW, Sydney, NSW, 2052, Australia
| | - Jun Ding
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 1192690
| | - Ajayan Vinu
- Global Innovative Center for Advanced Nanomaterials, School of Engineering, University of Newcastle, Callaghan, NSW, 2308, Australia
| | - Simon P Ringer
- School of Aerospace Mechanical & Mechatronic Engineering and Australian Centre for Microscopy & Microanalysis, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Jiabao Yi
- Global Innovative Center for Advanced Nanomaterials, School of Engineering, University of Newcastle, Callaghan, NSW, 2308, Australia
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Kiaba M, Suter A, Salman Z, Prokscha T, Chen B, Koster G, Dubroka A. Observation of Mermin-Wagner behavior in LaFeO 3/SrTiO 3 superlattices. Nat Commun 2024; 15:5313. [PMID: 38906872 PMCID: PMC11192889 DOI: 10.1038/s41467-024-49518-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 06/06/2024] [Indexed: 06/23/2024] Open
Abstract
Two-dimensional magnetic materials can exhibit new magnetic properties due to the enhanced spin fluctuations that arise in reduced dimension. However, the suppression of the long-range magnetic order in two dimensions due to long-wavelength spin fluctuations, as suggested by the Mermin-Wagner theorem, has been questioned for finite-size laboratory samples. Here we study the magnetic properties of a dimensional crossover in superlattices composed of the antiferromagnetic LaFeO3 and SrTiO3 that, thanks to their large lateral size, allowed examination using a sensitive magnetic probe - muon spin rotation spectroscopy. We show that the iron electronic moments in superlattices with 3 and 2 monolayers of LaFeO3 exhibit a static antiferromagnetic order. In contrast, in the superlattices with single LaFeO3 monolayer, the moments do not order and fluctuate to the lowest measured temperature as expected from the Mermin-Wagner theorem. Our work shows how dimensionality can be used to tune the magnetic properties of ultrathin films.
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Affiliation(s)
- M Kiaba
- Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Kotlářská 2, 611 37, Brno, Czech Republic.
| | - A Suter
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
| | - Z Salman
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
| | - T Prokscha
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
| | - B Chen
- Key Laboratory of Polar Materials and Devices (MOE) and Department of Electronics, East China Normal University, 200241, Shanghai, China
| | - G Koster
- MESA+ Institute for Nanotechnology, University of Twente, 7500 AE, Enschede, The Netherlands
| | - A Dubroka
- Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Kotlářská 2, 611 37, Brno, Czech Republic
- Central European Institute of Technology, Brno University of Technology, 612 00, Brno, Czech Republic
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Qi J, Zhao Y, Zhang Y, Yang G, Huang H, Lyu H, Shao B, Zhang J, Li J, Zhu T, Yu G, Wei H, Zhou S, Shen B, Wang S. Full electrical manipulation of perpendicular exchange bias in ultrathin antiferromagnetic film with epitaxial strain. Nat Commun 2024; 15:4734. [PMID: 38830907 PMCID: PMC11148026 DOI: 10.1038/s41467-024-49214-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 05/28/2024] [Indexed: 06/05/2024] Open
Abstract
Achieving effective manipulation of perpendicular exchange bias effect remains an intricate endeavor, yet it stands a significance for the evolution of ultra-high capacity and energy-efficient magnetic memory and logic devices. A persistent impediment to its practical applications is the reliance on external magnetic fields during the current-induced switching of exchange bias in perpendicularly magnetized structures. This study elucidates the achievement of a full electrical manipulation of the perpendicular exchange bias in the multilayers with an ultrathin antiferromagnetic layer. Owing to the anisotropic epitaxial strain in the 2-nm-thick IrMn3 layer, the considerable exchange bias effect is clearly achieved at room temperature. Concomitantly, a specific global uncompensated magnetization manifests in the IrMn3 layer, facilitating the switching of the irreversible portion of the uncompensated magnetization. Consequently, the perpendicular exchange bias can be manipulated by only applying pulsed current, notably independent of the presence of any external magnetic fields.
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Affiliation(s)
- Jie Qi
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei, 230601, China
| | - Yunchi Zhao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Yi Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Guang Yang
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, China
| | - He Huang
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Haochang Lyu
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Bokai Shao
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Jingyan Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Jialiang Li
- Spallation Neutron Source Science Center, Dongguan, 523803, China
| | - Tao Zhu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Spallation Neutron Source Science Center, Dongguan, 523803, China
| | - Guoqiang Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hongxiang Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Shiming Zhou
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei, 230601, China
| | - Baogen Shen
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei, 230601, China
| | - Shouguo Wang
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei, 230601, China.
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Baričić M, Nuñez JM, Aguirre MH, Hrabovsky D, Seydou M, Meneghini C, Peddis D, Ammar S. Advancements in polyol synthesis: expanding chemical horizons and Néel temperature tuning of CoO nanoparticles. Sci Rep 2024; 14:12529. [PMID: 38822019 PMCID: PMC11143313 DOI: 10.1038/s41598-024-54892-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 02/18/2024] [Indexed: 06/02/2024] Open
Abstract
The polyol synthesis of CoO nanoparticles (NPs) is typically conducted by dissolving and heating cobalt acetate tetrahydrate and water in diethylene glycol (DEG). This process yields aggregates of approximately 100 nm made of partially aligned primary crystals. However, the synthesis demands careful temperature control to allow the nucleation of CoO while simultaneously preventing reduction, caused by the activity of DEG. This restriction hinders the flexibility to freely adjust synthesis conditions, impeding the ability to obtain particles with varied morpho-structural properties, which, in turn, directly impact chemical and physical attributes. In this context, the growth of CoO NPs in polyol was studied focusing on the effect of the polyol chain length and the synthesis temperature at two different water/cations ratios. During this investigation, we found that longer polyol chains remove the previous limits of the method, allowing the tuning of aggregate size (20-150 nm), shape (spherical-octahedral), and crystalline length (8-35 nm). Regarding the characterization, our focus revolved around investigating the magnetic properties inherent in the synthesized products. From this point of view, two pivotal findings emerged. Firstly, we identified small quantities of a layered hydroxide ferromagnetic intermediate, which acted as interference in our measurements. This intermediate exhibited magnetic properties consistent with features observed in other publications on CoO produced in systems compatible with the intermediate formation. Optimal synthetic conditions that prevent the impurity from forming were found. This resolution clarifies several ambiguities existing in literature about CoO low-temperature magnetic behavior. Secondly, a regular relationship of the NPs' TN with their crystallite size was found, allowing us to regulate TN over ~ 80 K. For the first time, a branching was found in this structure-dependent magnetic feature, with samples of spheroidal morphology consistently having lower magnetic temperatures, when compared to samples with faceted/octahedral shape, providing compelling evidence for a novel physical parameter influencing the TN of a material. These two findings contribute to the understanding of the fundamental properties of CoO and antiferromagnetic materials.
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Affiliation(s)
- Miran Baričić
- ITODYS, UMR CNRS 7086, Université Paris Cité, 15 Rue de Jean Antoine de Baif, 75013, Paris, France.
- Istituto di Struttura della Materia, ISM-CNR, 00015, Monterotondo Scalo, Rome, Italy.
- Dipartimento di Scienza, Università degli Studi Roma Tre, Via della Vasca Navale, 84-00146, Rome, Italy.
| | - Jorge M Nuñez
- Instituto de Nanociencia y Nanotecnologìa, CNEA, CONICET, S. C., Bariloche, 8400, Rio Negro, Argentina
- Instituto Balseiro (UNCuyo, CNEA), Av. Bustillo 9500, S. C. de Bariloche 8400, Rio Negro, Argentina
- Instituto de Nanociencias y Materiales de Aragón-CSIC-Universidad de Zaragoza, Mariano Esquillor S/N, 50018, Zaragoza, Spain
- Laboratorio de Microscopías Avanzadas, Universidad de Zaragoza, Mariano Esquillor S/N, 50018, Zaragoza, Spain
- Dept. Física de La Materia Condensada, Universidad de Zaragoza, C/ Mariano Esquillor S/N, Zaragoza, Spain
| | - Myriam H Aguirre
- Instituto de Nanociencia y Nanotecnologìa, CNEA, CONICET, S. C., Bariloche, 8400, Rio Negro, Argentina
- Instituto Balseiro (UNCuyo, CNEA), Av. Bustillo 9500, S. C. de Bariloche 8400, Rio Negro, Argentina
- Instituto de Nanociencias y Materiales de Aragón-CSIC-Universidad de Zaragoza, Mariano Esquillor S/N, 50018, Zaragoza, Spain
| | - David Hrabovsky
- IMPMC, UMR CNRS 7590, Sorbonne Université, 6 Place Jussieu, 75005, Paris, France
| | - Mahamadou Seydou
- ITODYS, UMR CNRS 7086, Université Paris Cité, 15 Rue de Jean Antoine de Baif, 75013, Paris, France
| | - Carlo Meneghini
- Dipartimento di Scienza, Università degli Studi Roma Tre, Via della Vasca Navale, 84-00146, Rome, Italy
| | - Davide Peddis
- Università degli Studi di Genova, Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, 16146, Genova, Italy
| | - Souad Ammar
- ITODYS, UMR CNRS 7086, Université Paris Cité, 15 Rue de Jean Antoine de Baif, 75013, Paris, France
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5
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Sharma V, Pal S, Sharma D, Shukla DK, Chaudhary RJ, Okram GS. Size-induced exchange bias in single-phase CoO nanoparticles. NANOTECHNOLOGY 2024; 35:275702. [PMID: 38635294 DOI: 10.1088/1361-6528/ad3256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 03/10/2024] [Indexed: 04/19/2024]
Abstract
The tuning of exchange bias (EB) in nanoparticles has garnered significant attention due to its diverse range of applications. Here, we demonstrate EB in single-phase CoO nanoparticles, where two magnetic phases naturally emerge as the crystallite size decreases from 34.6 ± 0.8 to 10.8 ± 0.9 nm. The Néel temperature (TN) associated with antiferromagnetic ordering decreases monotonically with the reduction in crystallite size, highlighting the significant influence of size effects. The 34.6 nm nanoparticles exhibit magnetization irreversibility between zero-field cooled (ZFC) and field-cooled (FC) states belowTN. With further reduction in size this irreversibility appears well aboveTN, resulting in the absence of true paramagnetic regime which indicates the occurnace of an additional magnetic phase. The frequency-dependent ac-susceptibility in 10.8 nm nanoparticles suggests slow dynamics of disordered surface spins aboveTN, coinciding with the establishment of long-range order in the core. The thermoremanent magnetization (TRM) and iso-thermoremanent magnetization (IRM) curves suggest a core-shell structure: the core is antiferromagnetic, and the shell consists of disordered surface spins causing ferromagnetic interaction. Hence, the EB in these CoO nanoparticles results from the exchange coupling between an antiferromagnetic core and a disordered shell that exhibits unconventional surface spin characteristics.
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Affiliation(s)
- Vikash Sharma
- UGC-DAE Consortium for Scientific Research University campus, Khandwa road, Indore-452001, Madhya Pradesh, India
| | - Sudip Pal
- UGC-DAE Consortium for Scientific Research University campus, Khandwa road, Indore-452001, Madhya Pradesh, India
| | - Divya Sharma
- Govt. Girls PG College, Ujjain-456010, MP, India
| | - Dinesh Kumar Shukla
- UGC-DAE Consortium for Scientific Research University campus, Khandwa road, Indore-452001, Madhya Pradesh, India
| | - Ram Janay Chaudhary
- UGC-DAE Consortium for Scientific Research University campus, Khandwa road, Indore-452001, Madhya Pradesh, India
| | - Gunadhor Singh Okram
- UGC-DAE Consortium for Scientific Research University campus, Khandwa road, Indore-452001, Madhya Pradesh, India
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Feng T, Wang P, Wu D. 金属/铁磁绝缘体异质结中的自旋霍尔磁电阻. CHINESE SCIENCE BULLETIN-CHINESE 2022. [DOI: 10.1360/tb-2022-0186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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7
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Jin Q, Cheng H, Wang Z, Zhang Q, Lin S, Roldan MA, Zhao J, Wang JO, Chen S, He M, Ge C, Wang C, Lu HB, Guo H, Gu L, Tong X, Zhu T, Wang S, Yang H, Jin KJ, Guo EJ. Strain-Mediated High Conductivity in Ultrathin Antiferromagnetic Metallic Nitrides. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2005920. [PMID: 33289203 DOI: 10.1002/adma.202005920] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/19/2020] [Indexed: 06/12/2023]
Abstract
Strain engineering provides the ability to control the ground states and associated phase transition in epitaxial films. However, the systematic study of the intrinsic character and strain dependency in transition-metal nitrides remains challenging due to the difficulty in fabricating stoichiometric and high-quality films. Here the observation of an electronic state transition in highly crystalline antiferromagnetic CrN films with strain and reduced dimensionality is reported. By shrinking the film thickness to a critical value of ≈30 unit cells, a profound conductivity reduction accompanied by unexpected volume expansion is observed in CrN films. The electrical conductivity is observed surprisingly when the CrN layer is as thin as a single unit cell thick, which is far below the critical thickness of most metallic films. It is found that the metallicity of an ultrathin CrN film recovers from insulating behavior upon the removal of the as-grown strain by the fabrication of freestanding nitride films. Both first-principles calculations and linear dichroism measurements reveal that the strain-mediated orbital splitting effectively customizes the relatively small bandgap at the Fermi level, leading to an exotic phase transition in CrN. The ability to achieve highly conductive nitride ultrathin films by harnessing strain-control over competing phases can be used for utilizing their exceptional characteristics.
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Affiliation(s)
- Qiao Jin
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hu Cheng
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Zhiwen Wang
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Shan Lin
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Manuel A Roldan
- Eyring Materials Center, Arizona State University, Tempe, AZ, 85287, United States
| | - Jiali Zhao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Jia-Ou Wang
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Shuang Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, 450001, China
| | - Meng He
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Chen Ge
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Can Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Hui-Bin Lu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Haizhong Guo
- Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, 450001, China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Xin Tong
- China Spallation Neutron Source, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Tao Zhu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
- China Spallation Neutron Source, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Shanmin Wang
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Hongxin Yang
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
| | - Kui-Juan Jin
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Er-Jia Guo
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
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Baker AA, Lee JRI, Orme CA, van Buuren T, McCall SK. Suppression of low temperature magnetic ordering in samarium nanoparticles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:495803. [PMID: 32914765 DOI: 10.1088/1361-648x/abafc8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The role of finite size effects on magnetic order has been investigated in samarium nanoparticles prepared by physical vapor deposition. A dense layer composed of distinct nanoparticles with a mean particle diameter of 26 nm was deposited on a diamagnetic substrate. M(T) measurements identify the expected pair of antiferromagnetic ordering temperatures in the bulk Sm precursor, at 113 K and 14 K, where the magnetic unit cell for the lower ordering temperature is 10.36 nm along the c-axis. The high temperature ordering of the hexagonal sites in the Sm nanocrystals is slightly decreased with respect to that of bulk Sm, while the low temperature transition associated with the cubic sites is significantly suppressed. The observed changes are attributed to finite size effects, with ordering suppressed as the particle radius approaches the length of the magnetic unit cell, and surface moments become more prominent.
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Tuning the Néel temperature in an antiferromagnet: the case of Ni xCo 1-xO microstructures. Sci Rep 2019; 9:13584. [PMID: 31537821 PMCID: PMC6753089 DOI: 10.1038/s41598-019-49642-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 08/27/2019] [Indexed: 11/08/2022] Open
Abstract
We show that it is possible to tune the Néel temperature of nickel(II)-cobalt(II) oxide films by changing the Ni to Co ratio. We grow single crystalline micrometric triangular islands with tens of nanometers thickness on a Ru(0001) substrate using high temperature oxygen-assisted molecular beam epitaxy. Composition is controlled by adjusting the deposition rates of Co and Ni. The morphology, shape, crystal structure and composition are determined by low-energy electron microscopy and diffraction, and synchrotron-based x-ray absorption spectromicroscopy. The antiferromagnetic order is observed by x-ray magnetic linear dichroism. Antiferromagnetic domains up to micrometer width are observed.
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10
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Li J, Shi Z, Ortiz VH, Aldosary M, Chen C, Aji V, Wei P, Shi J. Spin Seebeck Effect from Antiferromagnetic Magnons and Critical Spin Fluctuations in Epitaxial FeF_{2} Films. PHYSICAL REVIEW LETTERS 2019; 122:217204. [PMID: 31283322 DOI: 10.1103/physrevlett.122.217204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Indexed: 06/09/2023]
Abstract
We report a longitudinal spin Seebeck effect (SSE) study in epitaxially grown FeF_{2}(110) antiferromagnetic (AFM) thin films with strong uniaxial anisotropy over the temperature range of 3.8-250 K. Both the magnetic-field and temperature-dependent SSE signals below the Néel temperature (T_{N}=70 K) of the FeF_{2} films are consistent with a theoretical model based on the excitations of AFM magnons without any net induced static magnetic moment. In addition to the characteristic low-temperature SSE peak associated with the AFM magnons, there is another SSE peak at T_{N} which extends well into the paramagnetic phase. All the SSE data taken at different magnetic fields up to 12 T near and above the critical point T_{N} follow the critical scaling law very well with the critical exponents for magnetic susceptibility of 3D Ising systems, which suggests that the AFM spin correlation is responsible for the observed SSE near T_{N}.
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Affiliation(s)
- Junxue Li
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Zhong Shi
- School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - Victor H Ortiz
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Mohammed Aldosary
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
- Department of Physics and Astronomy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Cliff Chen
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Vivek Aji
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Peng Wei
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Jing Shi
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
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11
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Wang F, Xiao D, Yuan W, Jiang J, Zhao YF, Zhang L, Yao Y, Liu W, Zhang Z, Liu C, Shi J, Han W, Chan MHW, Samarth N, Chang CZ. Observation of Interfacial Antiferromagnetic Coupling between Magnetic Topological Insulator and Antiferromagnetic Insulator. NANO LETTERS 2019; 19:2945-2952. [PMID: 30942075 DOI: 10.1021/acs.nanolett.9b00027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Inducing magnetic orders in a topological insulator (TI) to break its time reversal symmetry has been predicted to reveal many exotic topological quantum phenomena. The manipulation of magnetic orders in a TI layer can play a key role in harnessing these quantum phenomena toward technological applications. Here we fabricated a thin magnetic TI film on an antiferromagnetic (AFM) insulator Cr2O3 layer and found that the magnetic moments of the magnetic TI layer and the surface spins of the Cr2O3 layers favor interfacial AFM coupling. Field cooling studies show a crossover from negative to positive exchange bias clarifying the competition between the interfacial AFM coupling energy and the Zeeman energy in the AFM insulator layer. The interfacial exchange coupling also enhances the Curie temperature of the magnetic TI layer. The unique interfacial AFM alignment in magnetic TI on AFM insulator heterostructures opens a new route toward manipulating the interplay between topological states and magnetic orders in spin-engineered heterostructures, facilitating the exploration of proof-of-concept TI-based spintronic and electronic devices with multifunctionality and low power consumption.
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Affiliation(s)
- Fei Wang
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
- Shenyang National Laboratory for Materials Science, Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110016 , China
| | - Di Xiao
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Wei Yuan
- International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
- Department of Physics , University of California , Riverside , California 92521 , United States
| | - Jue Jiang
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Yi-Fan Zhao
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Ling Zhang
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Yunyan Yao
- International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
| | - Wei Liu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110016 , China
| | - Zhidong Zhang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110016 , China
| | - Chaoxing Liu
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Jing Shi
- Department of Physics , University of California , Riverside , California 92521 , United States
| | - Wei Han
- International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100871 , China
| | - Moses H W Chan
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Nitin Samarth
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Cui-Zu Chang
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
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12
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Li W, Wang Y, Cui XY, Yu S, Li Y, Hu Y, Zhu M, Zheng R, Ringer SP. Crystal Facet Effects on Nanomagnetism of Co 3O 4. ACS APPLIED MATERIALS & INTERFACES 2018; 10:19235-19247. [PMID: 29706073 DOI: 10.1021/acsami.8b03934] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The magnetic performance of nanomaterials depends on size, shape, and surface of the nanocrystals. Here, the exposed crystal planes of Co3O4 nanocrystals were analyzed to research the dependence of magnetic properties on the configuration environment of the ions exposed on different surfaces. The Co3O4 nanocrystals with exposed (1 0 0), (1 1 0), (1 1 1), and (1 1 2) planes were synthesized using a hydrothermal method in the shapes of nanocube, nanorod, hexagonal nanoplatelet, and nanolaminar, respectively. Ferromagnetic performance was detected in the (1 0 0) and (1 1 1) plane-exposed samples. First-principles calculation results indicate that unlike the nonmagnetic nature in the bulk, the Co3+ ions exposed on or close to the surface possess sizable magnetic moments because of the variation of coordination numbers and lattice distortion, which is responsible for the ferromagnetic-like behavior. The (1 1 0)-exposed sample keeps the natural antiferromagnetic behavior of bulk Co3O4 because either the surface Co3+ ions have no magnetic moments or their moments are in antiferromagnetic coupling. The (1 1 2)-exposed sample also displays antiferromagnetism because the interaction distances between the magnetized Co3+ ions are too long to form effective ferromagnetic coupling.
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Affiliation(s)
- Wenxian Li
- Institute of Materials, School of Materials Science and Engineering , Shanghai University , 149 Yanchang Road , Shanghai 200072 , China
- Institute for Sustainable Energy , Shanghai University , Shanghai 200444 , China
- Shanghai Key Laboratory of High Temperature Superconductors , Shanghai 200444 , China
| | - Yan Wang
- Institute of Materials, School of Materials Science and Engineering , Shanghai University , 149 Yanchang Road , Shanghai 200072 , China
| | | | - Shangjia Yu
- Institute of Materials, School of Materials Science and Engineering , Shanghai University , 149 Yanchang Road , Shanghai 200072 , China
| | - Ying Li
- Institute of Materials, School of Materials Science and Engineering , Shanghai University , 149 Yanchang Road , Shanghai 200072 , China
- Institute for Sustainable Energy , Shanghai University , Shanghai 200444 , China
| | - Yemin Hu
- Institute of Materials, School of Materials Science and Engineering , Shanghai University , 149 Yanchang Road , Shanghai 200072 , China
| | - Mingyuan Zhu
- Institute of Materials, School of Materials Science and Engineering , Shanghai University , 149 Yanchang Road , Shanghai 200072 , China
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13
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Cramer J, Fuhrmann F, Ritzmann U, Gall V, Niizeki T, Ramos R, Qiu Z, Hou D, Kikkawa T, Sinova J, Nowak U, Saitoh E, Kläui M. Magnon detection using a ferroic collinear multilayer spin valve. Nat Commun 2018. [PMID: 29540718 PMCID: PMC5852167 DOI: 10.1038/s41467-018-03485-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Information transport and processing by pure magnonic spin currents in insulators is a promising alternative to conventional charge-current-driven spintronic devices. The absence of Joule heating and reduced spin wave damping in insulating ferromagnets have been suggested for implementing efficient logic devices. After the successful demonstration of a majority gate based on the superposition of spin waves, further components are required to perform complex logic operations. Here, we report on magnetization orientation-dependent spin current detection signals in collinear magnetic multilayers inspired by the functionality of a conventional spin valve. In Y3Fe5O12|CoO|Co, we find that the detection amplitude of spin currents emitted by ferromagnetic resonance spin pumping depends on the relative alignment of the Y3Fe5O12 and Co magnetization. This yields a spin valve-like behavior with an amplitude change of 120% in our systems. We demonstrate the reliability of the effect and identify its origin by both temperature-dependent and power-dependent measurements.
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Affiliation(s)
- Joel Cramer
- Institute of Physics, Johannes Gutenberg-University Mainz, 55099, Mainz, Germany.,Graduate School of Excellence Materials Science in Mainz, 55128, Mainz, Germany
| | - Felix Fuhrmann
- Institute of Physics, Johannes Gutenberg-University Mainz, 55099, Mainz, Germany
| | - Ulrike Ritzmann
- Institute of Physics, Johannes Gutenberg-University Mainz, 55099, Mainz, Germany.,Department of Physics, University of Konstanz, 78457, Konstanz, Germany
| | - Vanessa Gall
- Department of Physics, University of Konstanz, 78457, Konstanz, Germany
| | - Tomohiko Niizeki
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Rafael Ramos
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Zhiyong Qiu
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,School of Materials Science and Engineering, Dalian University of Technology, Dalian, 116024, China
| | - Dazhi Hou
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Takashi Kikkawa
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Jairo Sinova
- Institute of Physics, Johannes Gutenberg-University Mainz, 55099, Mainz, Germany
| | - Ulrich Nowak
- Department of Physics, University of Konstanz, 78457, Konstanz, Germany
| | - Eiji Saitoh
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan.,Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, 319-1195, Japan
| | - Mathias Kläui
- Institute of Physics, Johannes Gutenberg-University Mainz, 55099, Mainz, Germany. .,Graduate School of Excellence Materials Science in Mainz, 55128, Mainz, Germany.
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14
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Schliesser JM, Huang B, Sahu SK, Asplund M, Navrotsky A, Woodfield BF. Experimental heat capacities, excess entropies, and magnetic properties of bulk and nano Fe3O4-Co3O4 and Fe3O4-Mn3O4 spinel solid solutions. J SOLID STATE CHEM 2018. [DOI: 10.1016/j.jssc.2018.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Barrera G, Celegato F, Coïsson M, Manzin A, Ferrarese Lupi F, Seguini G, Boarino L, Aprile G, Perego M, Tiberto P. Magnetization switching in high-density magnetic nanodots by a fine-tune sputtering process on a large-area diblock copolymer mask. NANOSCALE 2017; 9:16981-16992. [PMID: 29077107 DOI: 10.1039/c7nr04295g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ordered magnetic nanodot arrays with extremely high density provide unique properties to the growing field of nanotechnology. To overcome the size limitations of conventional lithography, a fine-tuned sputtering deposition process on mesoporous polymeric template fabricated by diblock copolymer self-assembly is herein proposed to fabricate uniform and densely spaced nanometer-scale magnetic dot arrays. This process was successfully exploited to pattern, over a large area, sputtered Ni80Fe20 and Co thin films with thicknesses of 10 and 13 nm, respectively. Carefully tuned sputter-etching at a suitable glancing angle was performed to selectively remove the magnetic material deposited on top of the polymeric template, producing nanodot arrays (dot diameter about 17 nm). A detailed study of magnetization reversal at room temperature as a function of sputter-etching time, together with morphology investigations, was performed to confirm the synthesis of long-range ordered arrays displaying functional magnetic properties. Magnetic hysteresis loops of the obtained nanodot arrays were measured at different temperatures and interpreted via micromagnetic simulations to explore the role of dipole-dipole magnetostatic interactions between dots and the effect of magnetocrystalline anisotropy. The agreement between measurements and numerical modelling results indicates the use of the proposed synthesis technique as an innovative process in the design of large-area nanoscale arrays of functional magnetic elements.
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Affiliation(s)
- G Barrera
- INRiM, Divisione Nanoscienze e materiali, Strada delle Cacce 91, 10135 Torino, Italy.
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16
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Hellman F, Hoffmann A, Tserkovnyak Y, Beach GSD, Fullerton EE, Leighton C, MacDonald AH, Ralph DC, Arena DA, Dürr HA, Fischer P, Grollier J, Heremans JP, Jungwirth T, Kimel AV, Koopmans B, Krivorotov IN, May SJ, Petford-Long AK, Rondinelli JM, Samarth N, Schuller IK, Slavin AN, Stiles MD, Tchernyshyov O, Thiaville A, Zink BL. Interface-Induced Phenomena in Magnetism. REVIEWS OF MODERN PHYSICS 2017; 89:025006. [PMID: 28890576 PMCID: PMC5587142 DOI: 10.1103/revmodphys.89.025006] [Citation(s) in RCA: 192] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially-driven magnetic effects and phenomena associated with spin-orbit coupling and intrinsic symmetry breaking at interfaces. It provides a historical background and literature survey, but focuses on recent progress, identifying the most exciting new scientific results and pointing to promising future research directions. It starts with an introduction and overview of how basic magnetic properties are affected by interfaces, then turns to a discussion of charge and spin transport through and near interfaces and how these can be used to control the properties of the magnetic layer. Important concepts include spin accumulation, spin currents, spin transfer torque, and spin pumping. An overview is provided to the current state of knowledge and existing review literature on interfacial effects such as exchange bias, exchange spring magnets, spin Hall effect, oxide heterostructures, and topological insulators. The article highlights recent discoveries of interface-induced magnetism and non-collinear spin textures, non-linear dynamics including spin torque transfer and magnetization reversal induced by interfaces, and interfacial effects in ultrafast magnetization processes.
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Affiliation(s)
- Frances Hellman
- Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Axel Hoffmann
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Geoffrey S D Beach
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Eric E Fullerton
- Center for Memory and Recording Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0401, USA
| | - Chris Leighton
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Allan H MacDonald
- Department of Physics, University of Texas at Austin, Austin, Texas 78712-0264, USA
| | - Daniel C Ralph
- Physics Department, Cornell University, Ithaca, New York 14853, USA; Kavli Institute at Cornell, Cornell University, Ithaca, New York 14853, USA
| | - Dario A Arena
- Department of Physics, University of South Florida, Tampa, Florida 33620-7100, USA
| | - Hermann A Dürr
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Peter Fischer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; Physics Department, University of California, 1156 High Street, Santa Cruz, California 94056, USA
| | - Julie Grollier
- Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Avenue Fresnel, 91767 Palaiseau, France
| | - Joseph P Heremans
- Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210, USA; Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, USA; Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Tomas Jungwirth
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53 Praha 6, Czech Republic; School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Alexey V Kimel
- Radboud University, Institute for Molecules and Materials, Nijmegen 6525 AJ, The Netherlands
| | - Bert Koopmans
- Department of Applied Physics, Center for NanoMaterials, COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Ilya N Krivorotov
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Steven J May
- Department of Materials Science & Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - Amanda K Petford-Long
- Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA; Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, USA
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Nitin Samarth
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ivan K Schuller
- Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, La Jolla, California 92093, USA; Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Andrei N Slavin
- Department of Physics, Oakland University, Rochester, Michigan 48309, USA
| | - Mark D Stiles
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6202, USA
| | - Oleg Tchernyshyov
- Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - André Thiaville
- Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris-Sud, 91405 Orsay, France
| | - Barry L Zink
- Department of Physics and Astronomy, University of Denver, Denver, CO 80208, USA
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17
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Kuświk P, Gastelois PL, Głowiński H, Przybylski M, Kirschner J. Impact of orthogonal exchange coupling on magnetic anisotropy in antiferromagnetic oxides/ferromagnetic systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:425001. [PMID: 27589202 DOI: 10.1088/0953-8984/28/42/425001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The influence of interface exchange coupling on magnetic anisotropy in the antiferromagnetic oxide/Ni system is investigated. We show how interfacial exchange coupling can be employed not only to pin the magnetization of the ferromagnetic layer but also to support magnetic anisotropy to orient the easy magnetization axis perpendicular to the film plane. The fact that this effect is only observed below the Néel temperature of all investigated antiferromagnetic oxides with significantly different magnetocrystalline anisotropies gives evidence that antiferromagnetic ordering is a source of the additional contribution to the perpendicular effective magnetic anisotropy.
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Affiliation(s)
- Piotr Kuświk
- Institute of Molecular Physics, Polish Academy of Sciences, 60179 Poznań, Poland. Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany
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18
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Spin-current probe for phase transition in an insulator. Nat Commun 2016; 7:12670. [PMID: 27573443 PMCID: PMC5013713 DOI: 10.1038/ncomms12670] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 07/20/2016] [Indexed: 11/10/2022] Open
Abstract
Spin fluctuation and transition have always been one of the central topics of magnetism and condensed matter science. Experimentally, the spin fluctuation is found transcribed onto scattering intensity in the neutron-scattering process, which is represented by dynamical magnetic susceptibility and maximized at phase transitions. Importantly, a neutron carries spin without electric charge, and therefore it can bring spin into a sample without being disturbed by electric energy. However, large facilities such as a nuclear reactor are necessary. Here we show that spin pumping, frequently used in nanoscale spintronic devices, provides a desktop microprobe for spin transition; spin current is a flux of spin without an electric charge and its transport reflects spin excitation. We demonstrate detection of antiferromagnetic transition in ultra-thin CoO films via frequency-dependent spin-current transmission measurements, which provides a versatile probe for phase transition in an electric manner in minute devices. Whilst neutron scattering is a powerful tool for studying spin fluctuations in materials, its availability is limited to large-scale user facilities. Here, the authors demonstrate how the pumping of pure spin currents can be used as a desktop probe to detect an antiferromagnetic transition.
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19
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Gómez‐Aguirre LC, Castro‐García S, Sánchez‐Andújar M, Yáñez‐Vilar S, Mira J, Bermúdez‐García JM, Centeno TA, Señarís‐Rodríguez MA. A Facile Synthesis of Co3O4 Hollow Microtubes by Decomposition of a Cobalt Metal–Organic Framework. Eur J Inorg Chem 2016. [DOI: 10.1002/ejic.201600192] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- L. Claudia Gómez‐Aguirre
- QuiMolMat Group CICA Department of Fundamental Chemistry Faculty of Sciences University of A Coruña Campus A Coruña 15071 A Coruña Spain
| | - Socorro Castro‐García
- QuiMolMat Group CICA Department of Fundamental Chemistry Faculty of Sciences University of A Coruña Campus A Coruña 15071 A Coruña Spain
| | - Manuel Sánchez‐Andújar
- QuiMolMat Group CICA Department of Fundamental Chemistry Faculty of Sciences University of A Coruña Campus A Coruña 15071 A Coruña Spain
| | - Susana Yáñez‐Vilar
- QuiMolMat Group CICA Department of Fundamental Chemistry Faculty of Sciences University of A Coruña Campus A Coruña 15071 A Coruña Spain
| | - Jorge Mira
- Department of Applied Physics University of Santiago de Compostela 15782 Santiago de Compostela Spain
| | - Juan Manuel Bermúdez‐García
- QuiMolMat Group CICA Department of Fundamental Chemistry Faculty of Sciences University of A Coruña Campus A Coruña 15071 A Coruña Spain
| | - Teresa A. Centeno
- Instituto Nacional del Carbón (INCAR‐CSIC) Apartado 73 33080 Oviedo Spain
| | - María Antonia Señarís‐Rodríguez
- QuiMolMat Group CICA Department of Fundamental Chemistry Faculty of Sciences University of A Coruña Campus A Coruña 15071 A Coruña Spain
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20
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Yuan W, Su T, Song Q, Xing W, Chen Y, Wang T, Zhang Z, Ma X, Gao P, Shi J, Han W. Crystal Structure Manipulation of the Exchange Bias in an Antiferromagnetic Film. Sci Rep 2016; 6:28397. [PMID: 27329336 PMCID: PMC4916595 DOI: 10.1038/srep28397] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 06/01/2016] [Indexed: 11/18/2022] Open
Abstract
Exchange bias is one of the most extensively studied phenomena in magnetism, since it exerts a unidirectional anisotropy to a ferromagnet (FM) when coupled to an antiferromagnet (AFM) and the control of the exchange bias is therefore very important for technological applications, such as magnetic random access memory and giant magnetoresistance sensors. In this letter, we report the crystal structure manipulation of the exchange bias in epitaxial hcp Cr2O3 films. By epitaxially growing twined oriented Cr2O3 thin films, of which the c axis and spins of the Cr atoms lie in the film plane, we demonstrate that the exchange bias between Cr2O3 and an adjacent permalloy layer is tuned to in-plane from out-of-plane that has been observed in oriented Cr2O3 films. This is owing to the collinear exchange coupling between the spins of the Cr atoms and the adjacent FM layer. Such a highly anisotropic exchange bias phenomenon is not possible in polycrystalline films.
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Affiliation(s)
- Wei Yuan
- International Center for Quantum Materials, Peking University, Beijing, 100871, P.R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P.R. China
| | - Tang Su
- International Center for Quantum Materials, Peking University, Beijing, 100871, P.R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P.R. China
| | - Qi Song
- International Center for Quantum Materials, Peking University, Beijing, 100871, P.R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P.R. China
| | - Wenyu Xing
- International Center for Quantum Materials, Peking University, Beijing, 100871, P.R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P.R. China
| | - Yangyang Chen
- International Center for Quantum Materials, Peking University, Beijing, 100871, P.R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P.R. China
| | - Tianyu Wang
- International Center for Quantum Materials, Peking University, Beijing, 100871, P.R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P.R. China
| | - Zhangyuan Zhang
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, P.R. China
- Department of Physics and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072, P.R. China
| | - Xiumei Ma
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, P.R. China
| | - Peng Gao
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P.R. China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, P.R. China
| | - Jing Shi
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Wei Han
- International Center for Quantum Materials, Peking University, Beijing, 100871, P.R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P.R. China
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21
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Lin W, Chen K, Zhang S, Chien CL. Enhancement of Thermally Injected Spin Current through an Antiferromagnetic Insulator. PHYSICAL REVIEW LETTERS 2016; 116:186601. [PMID: 27203336 DOI: 10.1103/physrevlett.116.186601] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Indexed: 06/05/2023]
Abstract
We report a large enhancement of thermally injected spin current in normal metal (NM)/antiferromagnet (AF)/yttrium iron garnet (YIG), where a thin AF insulating layer of NiO or CoO can enhance the spin current from YIG to a NM by up to a factor of 10. The spin current enhancement in NM/AF/YIG, with a pronounced maximum near the Néel temperature of the thin AF layer, has been found to scale linearly with the spin-mixing conductance at the NM/YIG interface for NM=3d, 4d, and 5d metals. Calculations of spin current enhancement and spin mixing conductance are qualitatively consistent with the experimental results.
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Affiliation(s)
- Weiwei Lin
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Kai Chen
- Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
| | - Shufeng Zhang
- Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
| | - C L Chien
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
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22
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Frangou L, Oyarzún S, Auffret S, Vila L, Gambarelli S, Baltz V. Enhanced Spin Pumping Efficiency in Antiferromagnetic IrMn Thin Films around the Magnetic Phase Transition. PHYSICAL REVIEW LETTERS 2016; 116:077203. [PMID: 26943556 DOI: 10.1103/physrevlett.116.077203] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Indexed: 06/05/2023]
Abstract
We report the measurement of a spin pumping effect due to fluctuations of the magnetic order of IrMn thin films. A precessing NiFe ferromagnet injected spins into IrMn spin sinks, and enhanced damping was observed around the IrMn magnetic phase transition. Our data were compared to a recently developed theory and converted into interfacial spin mixing conductance enhancements. By spotting the spin pumping peak, the thickness dependence of the IrMn critical temperature could be determined and the characteristic length for the spin-spin interactions was deduced.
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Affiliation(s)
- L Frangou
- Univ. Grenoble Alpes, SPINTEC, F-38000 Grenoble, France
- CNRS, SPINTEC, F-38000 Grenoble, France
- CEA, INAC-SPINTEC, F-38000 Grenoble, France
| | - S Oyarzún
- Univ. Grenoble Alpes, NM, F-38000 Grenoble, France
- CEA, INAC-NM, F-38000 Grenoble, France
| | - S Auffret
- Univ. Grenoble Alpes, SPINTEC, F-38000 Grenoble, France
- CNRS, SPINTEC, F-38000 Grenoble, France
- CEA, INAC-SPINTEC, F-38000 Grenoble, France
| | - L Vila
- Univ. Grenoble Alpes, NM, F-38000 Grenoble, France
- CEA, INAC-NM, F-38000 Grenoble, France
| | - S Gambarelli
- Univ. Grenoble Alpes, SCIB, F-38000 Grenoble, France
- CEA, INAC-SCIB, F-38000 Grenoble, France
| | - V Baltz
- Univ. Grenoble Alpes, SPINTEC, F-38000 Grenoble, France
- CNRS, SPINTEC, F-38000 Grenoble, France
- CEA, INAC-SPINTEC, F-38000 Grenoble, France
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23
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Lamirand AD, Soares MM, De Santis M, Ramos AY, Grenier S, Tolentino HCN. Strain driven monoclinic distortion of ultrathin CoO films in the exchange-coupled CoO/FePt/Pt(0 0 1) system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:085001. [PMID: 25604708 DOI: 10.1088/0953-8984/27/8/085001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The structure and strain of ultrathin CoO films grown on a Pt(0 0 1) substrate and on a ferromagnetic FePt pseudomorphic layer on Pt(0 0 1) have been determined with in situ and real time surface x-ray diffraction. The films grow epitaxially on both surfaces with an in-plane hexagonal pattern that yields a pseudo-cubic CoO(1 1 1) surface. A refined x-ray diffraction analysis reveals a slight monoclinic distortion at RT induced by the anisotropic stress at the interface. The tetragonal contribution to the distortion results in a ratio [Formula: see text], opposite to that found in the low temperature bulk CoO phase. This distortion leads to a stable Co(2+) spin configuration within the plane of the film.
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Affiliation(s)
- Anne D Lamirand
- Université Grenoble Alpes, Institut Néel, F-38042 Grenoble, France. CNRS, Institut Néel, F-38042 Grenoble, France
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24
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Zhang W, Jungfleisch MB, Jiang W, Pearson JE, Hoffmann A, Freimuth F, Mokrousov Y. Spin Hall effects in metallic antiferromagnets. PHYSICAL REVIEW LETTERS 2014; 113:196602. [PMID: 25415914 DOI: 10.1103/physrevlett.113.196602] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Indexed: 06/04/2023]
Abstract
We investigate four CuAu-I-type metallic antiferromagnets for their potential as spin current detectors using spin pumping and inverse spin Hall effect. Nontrivial spin Hall effects were observed for FeMn, PdMn, and IrMn while a much higher effect was obtained for PtMn. Using thickness-dependent measurements, we determined the spin diffusion lengths of these materials to be short, on the order of 1 nm. The estimated spin Hall angles of the four materials follow the relationship PtMn>IrMn>PdMn>FeMn, highlighting the correlation between the spin-orbit coupling of nonmagnetic species and the magnitude of the spin Hall effect in their antiferromagnetic alloys. These experiments are compared with first-principles calculations. Engineering the properties of the antiferromagnets as well as their interfaces can pave the way for manipulation of the spin dependent transport properties in antiferromagnet-based spintronics.
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Affiliation(s)
- Wei Zhang
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | | | - Wanjun Jiang
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - John E Pearson
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Axel Hoffmann
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Frank Freimuth
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany
| | - Yuriy Mokrousov
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany
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25
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Yang Z, Gao D, Tao K, Zhang J, Shi Z, Xu Q, Shi S, Xue D. A series of unexpected ferromagnetic behaviors based on the surface-vacancy state: an insight into NiO nanoparticles with a core–shell structure. RSC Adv 2014. [DOI: 10.1039/c4ra06472k] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We propose that the observed anomalous ferromagnetic behavior of NiO nanoparticles is due to the formation of a ferromagnetic particle shell that is oxygen-vacancy related.
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Affiliation(s)
- Zhaolong Yang
- Key Laboratory for Magnetism and Magnetic Materials of MOE
- Lanzhou University
- Lanzhou 730000, P. R. China
| | - Daqiang Gao
- Key Laboratory for Magnetism and Magnetic Materials of MOE
- Lanzhou University
- Lanzhou 730000, P. R. China
| | - Kun Tao
- Key Laboratory for Magnetism and Magnetic Materials of MOE
- Lanzhou University
- Lanzhou 730000, P. R. China
| | - Jing Zhang
- Key Laboratory for Magnetism and Magnetic Materials of MOE
- Lanzhou University
- Lanzhou 730000, P. R. China
| | - Zhenhua Shi
- Key Laboratory for Magnetism and Magnetic Materials of MOE
- Lanzhou University
- Lanzhou 730000, P. R. China
| | - Qiang Xu
- Key Laboratory for Magnetism and Magnetic Materials of MOE
- Lanzhou University
- Lanzhou 730000, P. R. China
| | - Shoupeng Shi
- Key Laboratory for Magnetism and Magnetic Materials of MOE
- Lanzhou University
- Lanzhou 730000, P. R. China
| | - Desheng Xue
- Key Laboratory for Magnetism and Magnetic Materials of MOE
- Lanzhou University
- Lanzhou 730000, P. R. China
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26
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Wang Y, Kong L, Pasquale FL, Cao Y, Dong B, Tanabe I, Binek C, Dowben PA, Kelber JA. Graphene mediated domain formation in exchange coupled graphene/Co3O4(111)/Co(0001) trilayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:472203. [PMID: 24154506 DOI: 10.1088/0953-8984/25/47/472203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Graphene grown directly on Co3O4(111)/Co(0001) by molecular beam epitaxy exhibits extrinsic p-type doping, as demonstrated by photoemission and conductivity measurements. Trilayer heterostructures of graphene/Co3O4(111)/Co(0001) reveal an unconventional magneto-optical Kerr hysteresis with vanishing remanence for temperatures up to 400 K. Magnetic force microscopy measurements demonstrate that the vanishing remanence is due to a complex domain state, indicating substrate-induced graphene spin polarization. The domain formation of the Co magnetization is in strong contrast to the magnetic behavior of Co in Co/Co3O4 bilayers. This suggests that the Co3O4 interlayer mediates the variable Co magnetization and induced graphene spin polarization, with possible retroaction of graphene on the Co film.
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Affiliation(s)
- Yi Wang
- Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, Theodore Jorgensen Hall, 855 North 16th Street, University of Nebraska, PO Box 880299, Lincoln, NE 68588-0299, USA
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27
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Spizzo F, Tamisari M, Bonfiglioli E, Del Bianco L. Detection of the dynamic magnetic behavior of the antiferromagnet in exchange-coupled NiFe/IrMn bilayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:386001. [PMID: 23988438 DOI: 10.1088/0953-8984/25/38/386001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The magnetothermal behavior of antiferromagnetic IrMn layers of different thickness (3, 6, 10 nm) has been studied by exploiting the exchange coupling with a ferromagnetic 5 nm-thick NiFe layer. A procedure has been devised for the measurement of the magnetization of the NiFe/IrMn bilayers as a function of temperature and time at different values of an external magnetic field, Hinv, antiparallel to the unidirectional exchange anisotropy. This analysis allows one to probe the effective distribution of anisotropy energy barriers of the antiferromagnetic phase, as sensed by the ferromagnetic layer. Two magnetic regimes have been distinguished. At temperature T < 100 K, the interfacial IrMn spins are frozen in a glassy state and are collectively involved in the exchange coupling with the NiFe spins. At T ∼ 100 K the collective state breaks up; thus, above this temperature, only the interfacial IrMn spins which are tightly polarized by the IrMn nanograins, forming the bulk of the layer, are effectively involved in the exchange coupling mechanism. Due to that, for T > 100 K the exchange coupling is ruled by the anisotropy energy barriers of the bulk IrMn nanograins, namely by the layer thickness. The thermal evolution of the exchange field and of the coercivity in the three samples is coherently explained in the framework of this description of the dynamic magnetic behavior of the IrMn phase.
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Affiliation(s)
- F Spizzo
- Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, I-44122 Ferrara, Italy
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28
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Dai Q, Tang J. The optical and magnetic properties of CoO and Co nanocrystals prepared by a facile technique. NANOSCALE 2013; 5:7512-7519. [PMID: 23832010 DOI: 10.1039/c3nr01971c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
CoO and Co nanocrystals with cubic crystal structures were prepared by thermal decomposition of cobalt(II) acetate tetrahydrate in a mixture of oleylamine and oleic acid under the protection of nitrogen gas at 300 °C for 2 h. The products of CoO or Co nanocrystals are determined by the relative amount of oleylamine due to its reducibility. The sizes and shapes of CoO or Co can be controlled by the ratio of cobalt : oleylamine : oleic acid due to different binding capabilities of the two capping ligands (oleylamine and oleic acid). A modification of the surface state by surface passivation arising from the capping ligands for CoO nanocrystals leads to the blue shift of the ligand-metal charge transfer (LMCT) absorption. Room temperature ferromagnetism originating from uncompensated surface spins, as well as magnetic moments weakly exchange coupled to the CoO lattice due to defects inside CoO nanoparticles, are observed. The magnetic behaviors of CoO and Co nanoparticles also shed light on the synthesis and the magnetic properties of the antiferromagnetic and ferromagnetic nanomaterials.
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Affiliation(s)
- Qilin Dai
- Department of Physics & Astronomy, University of Wyoming, Laramie, WY 82071, USA
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29
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Wang BY, Hong JY, Yang KHO, Chan YL, Wei DH, Lin HJ, Lin MT. How antiferromagnetism drives the magnetization of a ferromagnetic thin film to align out of plane. PHYSICAL REVIEW LETTERS 2013; 110:117203. [PMID: 25166570 DOI: 10.1103/physrevlett.110.117203] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Revised: 01/07/2013] [Indexed: 06/03/2023]
Abstract
Interfacial moments of an antiferromagnet are known for their prominent effects of induced coercivity enhancement and exchange bias in ferromagnetic-antiferromagnetic exchange-coupled systems. Here we report that the unpinned moments of an antiferromagnetic face-centered-cubic Mn layer can drive the magnetization of an adjacent Fe film perpendicular owing to a formation of intrinsic perpendicular anisotropy. X-ray magnetic circular dichroism and hysteresis loops show establishment of perpendicular magnetization on Fe/Mn bilayers while temperature was decreased. The fact that the magnitude of perpendicular anisotropy of the Fe layer is enhanced proportionally to the out-of-plane oriented orbital moment of the Mn unpinned layer, rather than that of Fe itself, gives evidence for the Mn unpinned moments to be the origin of the established perpendicular magnetization.
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Affiliation(s)
- Bo-Yao Wang
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Jhen-Yong Hong
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Kui-Hon Ou Yang
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Yuet-Loy Chan
- National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan
| | - Der-Hsin Wei
- National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan
| | - Hong-Ji Lin
- National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan
| | - Minn-Tsong Lin
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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30
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31
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Sytnyk M, Kirchschlager R, Bodnarchuk MI, Primetzhofer D, Kriegner D, Enser H, Stangl J, Bauer P, Voith M, Hassel AW, Krumeich F, Ludwig F, Meingast A, Kothleitner G, Kovalenko MV, Heiss W. Tuning the magnetic properties of metal oxide nanocrystal heterostructures by cation exchange. NANO LETTERS 2013; 13:586-93. [PMID: 23362940 PMCID: PMC3573734 DOI: 10.1021/nl304115r] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 01/26/2013] [Indexed: 05/15/2023]
Abstract
For three types of colloidal magnetic nanocrystals, we demonstrate that postsynthetic cation exchange enables tuning of the nanocrystal's magnetic properties and achieving characteristics not obtainable by conventional synthetic routes. While the cation exchange procedure, performed in solution phase approach, was restricted so far to chalcogenide based semiconductor nanocrystals, here ferrite-based nanocrystals were subjected to a Fe(2+) to Co(2+) cation exchange procedure. This allows tracing of the compositional modifications by systematic and detailed magnetic characterization. In homogeneous magnetite nanocrystals and in gold/magnetite core shell nanocrystals the cation exchange increases the coercivity field, the remanence magnetization, as well as the superparamagnetic blocking temperature. For core/shell nanoheterostructures a selective doping of either the shell or predominantly of the core with Co(2+) is demonstrated. By applying the cation exchange to FeO/CoFe(2)O(4) core/shell nanocrystals the Neél temperature of the core material is increased and exchange-bias effects are enhanced so that vertical shifts of the hysteresis loops are obtained which are superior to those in any other system.
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Affiliation(s)
- Mykhailo Sytnyk
- Institute of Semiconductor and
Solid State Physics, University Linz, Altenbergerstraße
69, 4040 Linz, Austria
| | - Raimund Kirchschlager
- Institute of Semiconductor and
Solid State Physics, University Linz, Altenbergerstraße
69, 4040 Linz, Austria
| | - Maryna I. Bodnarchuk
- Institute of Inorganic Chemistry,
Department of Chemistry and Applied Biosciences, ETH
Zurich, CH-8093, Switzerland
- Laboratory for Thin Films and
Photovoltaics, EMPA-Swiss Federal Laboratories for Materials
Science and Technology, CH-8060, Switzerland
| | - Daniel Primetzhofer
- Ion physics, Department of Physics
and Astronomy, Uppsala University, 75120
Uppsala, Sweden
| | - Dominik Kriegner
- Institute of Semiconductor and
Solid State Physics, University Linz, Altenbergerstraße
69, 4040 Linz, Austria
| | - Herbert Enser
- Institute of Semiconductor and
Solid State Physics, University Linz, Altenbergerstraße
69, 4040 Linz, Austria
| | - Julian Stangl
- Institute of Semiconductor and
Solid State Physics, University Linz, Altenbergerstraße
69, 4040 Linz, Austria
| | - Peter Bauer
- Institute
of Experimental Physics, University Linz, 4040 Linz, Austria
| | - Michael Voith
- Institute
for Chemical Technology
of Inorganic Materials, University Linz, 4040 Linz, Austria
| | - Achim Walter Hassel
- Institute
for Chemical Technology
of Inorganic Materials, University Linz, 4040 Linz, Austria
| | - Frank Krumeich
- Institute of Inorganic Chemistry,
Department of Chemistry and Applied Biosciences, ETH
Zurich, CH-8093, Switzerland
| | - Frank Ludwig
- Institut
für Elektrische Messtechnik
und Grundlagen der Elektrotechnik, TU Braunschweig, 38106 Braunschweig, Germany
| | - Arno Meingast
- Austrian Centre for Electron
Microscopy and Nanoanalysis, Institute for Electron Microscopy, Graz University of Technology, 8010 Graz, Austria
| | - Gerald Kothleitner
- Austrian Centre for Electron
Microscopy and Nanoanalysis, Institute for Electron Microscopy, Graz University of Technology, 8010 Graz, Austria
| | - Maksym V. Kovalenko
- Institute of Inorganic Chemistry,
Department of Chemistry and Applied Biosciences, ETH
Zurich, CH-8093, Switzerland
- Laboratory for Thin Films and
Photovoltaics, EMPA-Swiss Federal Laboratories for Materials
Science and Technology, CH-8060, Switzerland
| | - Wolfgang Heiss
- Institute of Semiconductor and
Solid State Physics, University Linz, Altenbergerstraße
69, 4040 Linz, Austria
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32
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Dai Q, Tang J. Magnetic properties of CoO nanocrystals prepared with a controlled reaction atmosphere. RSC Adv 2013. [DOI: 10.1039/c3ra40834e] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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33
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Wu HC, Liao ZM, Sofin RGS, Feng G, Ma XM, Shick AB, Mryasov ON, Shvets IV. Mn2Au: body-centered-tetragonal bimetallic antiferromagnets grown by molecular beam epitaxy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:6374-6379. [PMID: 22996352 DOI: 10.1002/adma.201202273] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 08/23/2012] [Indexed: 06/01/2023]
Abstract
Mn(2)Au, a layered bimetal, is successfully grown using molecular beam epitaxy (MBE). The experiments and theoretical calculations presented suggest that Mn(2)Au film is antiferromagnetic with a very low critical temperature. The antiferromagnetic nature is demonstrated by measuring the exchange-bias effect of Mn(2)Au/Fe bilayers. This study establishes a primary basis for further research of this new antiferromagnet in spin-electronic device applications.
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Affiliation(s)
- Han-Chun Wu
- School of Physics and CRANN, Trinity College Dublin, Ireland.
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34
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Lodi Rizzini A, Krull C, Balashov T, Mugarza A, Nistor C, Yakhou F, Sessi V, Klyatskaya S, Ruben M, Stepanow S, Gambardella P. Exchange biasing single molecule magnets: coupling of TbPc2 to antiferromagnetic layers. NANO LETTERS 2012; 12:5703-7. [PMID: 23046484 DOI: 10.1021/nl302918d] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We investigate the possibility to induce exchange bias between single molecule magnets (SMM) and metallic or oxide antiferromagnetic substrates. Element-resolved X-ray magnetic circular dichroism measurements reveal, respectively, the presence and absence of unidirectional exchange anisotropy for TbPc(2) SMM deposited on antiferromagnetic Mn and CoO layers. TbPc(2) deposited on Mn thin films present magnetic hysteresis and a negative horizontal shift of the Tb magnetization loop after field cooling, consistent with the observation of pinned spins in the Mn layer coupled parallel to the Tb magnetic moment. Conversely, molecules deposited on CoO substrates present paramagnetic magnetization loops with no indication of exchange bias. These experiments demonstrate the ability of SMM to polarize the pinned uncompensated spins of an antiferromagnet during field-cooling and realize metal-organic exchange-biased heterostructures using antiferromagnetic pinning layers.
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Affiliation(s)
- A Lodi Rizzini
- Catalan Institute of Nanotechnology (ICN), UAB Campus, E-08193 Barcelona, Spain
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35
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Zhang J, Wang Y, Li S, Wang X, Huang F, Xie A, Shen Y. Controlled synthesis, growth mechanism and optical properties of FeWO4 hierarchical microstructures. CrystEngComm 2011. [DOI: 10.1039/c1ce05416c] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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36
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Wang G, Liu H, Horvat J, Wang B, Qiao S, Park J, Ahn H. Highly Ordered Mesoporous Cobalt Oxide Nanostructures: Synthesis, Characterisation, Magnetic Properties, and Applications for Electrochemical Energy Devices. Chemistry 2010; 16:11020-7. [DOI: 10.1002/chem.201000562] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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37
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Synthesis of Co3O4 nanoparticles by oxidation-reduction method and its magnetic characterization. OPEN CHEM 2009. [DOI: 10.2478/s11532-009-0012-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AbstractWithout any surfactant, antiferromagnetic Co3O4 nanoparticles were synthesized successfully for the first time by means of an oxidation-reduction method with cobalt sulfate as starting material, which was oxidized to cobalt salt by NaNO3 after alkalinizing with NaOH. Morphological, structural, spectroscopic and magnetic characterization of the product were done by SEM, TEM, XRD, and VSM, respectively. The average crystallite size (on the base of line profile fitting method), D and σ, is estimated as 30 ± 6 nm. Some anomalous magnetic properties and their enhanced effect have been observed in Co3O4 antiferromagnetic nanocrystallites, including a bias field, coercivity, permanent magnetic moments and an open loop. These phenomena are attributed to the unidirectional anisotropy which is caused by the exchange coupling between AFM and FM layers, the existence of the spin glass like surface spins of Co3O4 nanoparticles due to size effects and surface-area effect.
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38
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Mulders AM, Loosvelt H, Fraile Rodríguez A, Popova E, Konishi T, Temst K, Karis O, Arvanitis D, Van Haesendonck C. On the interface magnetism of thin oxidized Co films: orbital and spin moments. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:124211. [PMID: 21817453 DOI: 10.1088/0953-8984/21/12/124211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
An x-ray magnetic circular dichroism study of a polycrystalline Co/CoO bilayer is presented. Using both the chemical specificity and surface sensitivity in the core level techniques, we find that uncompensated Co(2+) spin moments participate in the remanent ferromagnetic response of the bilayer that has oxygen nearest neighbors. These are likely located at the Co/CoO interface. As intermixing of magnetic species is not present in Co/CoO, it is concluded that the observed interface moments are due to interface roughness. Given their direction, these moments appear to not directly correlate to the exchange bias in these bilayers.
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Affiliation(s)
- A M Mulders
- Department of Physics, Uppsala University, Box 530, 751 21 Uppsala, Sweden. Department of Imaging and Applied Physics, Curtin University of Technology, Perth, WA 6845, Australia. The Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, NSW 2234, Australia
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39
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Zhou YX, Yao HB, Zhang Q, Gong JY, Liu SJ, Yu SH. Hierarchical FeWO4 Microcrystals: Solvothermal Synthesis and Their Photocatalytic and Magnetic Properties. Inorg Chem 2009; 48:1082-90. [DOI: 10.1021/ic801806r] [Citation(s) in RCA: 183] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yu-Xue Zhou
- Division of Nanomaterials & Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, The School of Chemistry & Materials, Department of Materials of Science and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Hong-Bin Yao
- Division of Nanomaterials & Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, The School of Chemistry & Materials, Department of Materials of Science and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Qiao Zhang
- Division of Nanomaterials & Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, The School of Chemistry & Materials, Department of Materials of Science and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Jun-Yan Gong
- Division of Nanomaterials & Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, The School of Chemistry & Materials, Department of Materials of Science and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Shu-Juan Liu
- Division of Nanomaterials & Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, The School of Chemistry & Materials, Department of Materials of Science and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Shu-Hong Yu
- Division of Nanomaterials & Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, The School of Chemistry & Materials, Department of Materials of Science and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
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40
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Kahn ML, Glaria A, Pages C, Monge M, Saint Macary L, Maisonnat A, Chaudret B. Organometallic chemistry: an alternative approach towards metal oxide nanoparticles. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b818935h] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Inderhees SE, Borchers JA, Green KS, Kim MS, Sun K, Strycker GL, Aronson MC. Manipulating the magnetic structure of Co core/CoO shell nanoparticles: implications for controlling the exchange bias. PHYSICAL REVIEW LETTERS 2008; 101:117202. [PMID: 18851323 DOI: 10.1103/physrevlett.101.117202] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2008] [Indexed: 05/26/2023]
Abstract
We present an experimental study of the effects of oxidation on the magnetic and crystal structures of exchange biased epsilon-Co/CoO core-shell nanoparticles. Transmission electron microscopy measurements reveal that oxidation creates a Co-CoO interface which is highly directional and epitaxial in quality. Neutron diffraction measurements find that below a Néel temperature TN of approximately 235 K the magnetization of the CoO shell is modulated by two wave vectors, q1=(1/2 1/2 1/2)2pi/a and q2=(100)2pi/a. Oxidation affects the q1 component of the magnetization very little, but hugely enhances the q2 component, resulting in the magnetic decompensation of the core-shell interface. We propose that the large exchange bias effect results from the highly ordered interface between the Co core and CoO shell, and from enhanced core-shell coupling by the uncompensated interface moment.
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Affiliation(s)
- S E Inderhees
- University of Michigan, Ann Arbor, Michigan 48109-1120, USA
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42
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Glaria A, Kahn ML, Lecante P, Barbara B, Chaudret B. Fe1−yO Nanoparticles: Organometallic Synthesis and Magnetic Properties. Chemphyschem 2008; 9:776-80. [DOI: 10.1002/cphc.200700817] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Zhang W, Han M, Jiang Z, Song Y, Xie Z, Xu Z, Zheng L. Controllable Synthesis of CoO Nanosheets and their Magnetic Properties. Chemphyschem 2007; 8:2091-5. [PMID: 17722212 DOI: 10.1002/cphc.200700398] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Wenli Zhang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China
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Size dependence of phase transition temperatures of ferromagnetic, ferroelectric and superconductive nanocrystals. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/s11467-007-0049-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Zhang HT, Chen XH. Controlled synthesis and anomalous magnetic properties of relatively monodisperse CoO nanocrystals. NANOTECHNOLOGY 2005; 16:2288-2294. [PMID: 20818009 DOI: 10.1088/0957-4484/16/10/051] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Monodisperse cobalt monoxide (CoO) nanocrystals ranging in size from 4.5 to 23 nm were prepared via the thermal decomposition of cobalt acetylacetonate (Co(acac)(2)) in oleylamine under vigorous stirring. The size control of the nanocrystals was achieved by tailoring the reaction temperature or by seed-mediated growth. The nanocrystals have been characterized by x-ray diffraction, transmission electron microscopy, and Fourier transform infrared and x-ray photoelectron spectroscopy. The as-prepared nanocrystals are stable because of the organic coating (oleylamine) that occurred in situ. Magnetic measurement reveals that all of the nanocrystals are superparamagnetic at high temperatures and show ferromagnetic interactions at low temperatures due to the existence of uncompensated moments on the surface of the nanoparticles. The weak ferromagnetic interactions increase with decreasing particle size.
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Affiliation(s)
- Hai-Tao Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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Gruyters M. Spin-glass-like behavior in CoO nanoparticles and the origin of exchange bias in layered CoO/ferromagnet structures. PHYSICAL REVIEW LETTERS 2005; 95:077204. [PMID: 16196820 DOI: 10.1103/physrevlett.95.077204] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2005] [Indexed: 05/04/2023]
Abstract
The magnetic behavior of CoO nanoparticles and layered CoO/ferromagnetic (FM) structures has been investigated by magnetization and hysteresis loop measurements. In the amorphous CoO, a large uncompensation of spins is found that is closely related to spin-glass-like behavior below a freezing temperature T(F) approximately 215-220 K. The spin-glass-like phase may be described by the de Almeida-Thouless line for Ising spin systems. The exchange bias in the layered CoO/FM structures is explained by the spin-glass-like state in the nanoparticles constituting the CoO film.
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Affiliation(s)
- M Gruyters
- Humboldt-Universität zu Berlin, Institut für Physik, Berlin, Germany
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Weschke E, Ott H, Schierle E, Schüssler-Langeheine C, Vyalikh DV, Kaindl G, Leiner V, Ay M, Schmitte T, Zabel H, Jensen PJ. Finite-size effect on magnetic ordering temperatures in long-period antiferromagnets: holmium thin films. PHYSICAL REVIEW LETTERS 2004; 93:157204. [PMID: 15524935 DOI: 10.1103/physrevlett.93.157204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2003] [Revised: 04/28/2004] [Indexed: 05/24/2023]
Abstract
The thickness dependence of the helical antiferromagnetic ordering temperature T(N) was studied for thin Ho metal films by resonant magnetic soft x-ray and neutron diffraction. In contrast with the Curie temperature of ferromagnets, T(N) was found to decrease with film thickness d according to [T(N)(infinity)-T(N)(d)]/T(N)(d) proportional variant (d-d(0))(-lambda(')), where lambda(') is a phenomenological exponent and d(0) is of the order of the bulk magnetic period L(b). These observations are reproduced by mean-field calculations that suggest a linear relationship between d(0) and L(b) in long-period antiferromagnets.
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Affiliation(s)
- E Weschke
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
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van der Zaag PJ, Ijiri Y, Borchers JA, Feiner LF, Wolf RM, Gaines JM, Erwin RW, Verheijen MA. Difference between blocking and Néel temperatures in the exchange biased Fe3O4/CoO system. PHYSICAL REVIEW LETTERS 2000; 84:6102-6105. [PMID: 10991134 DOI: 10.1103/physrevlett.84.6102] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2000] [Indexed: 05/23/2023]
Abstract
The blocking temperature T(B) has been determined as a function of the antiferromagnetic layer thickness in the Fe3O4/CoO exchange biased system. For CoO layers thinner than 50 A, T(B) is reduced below the Néel temperature T(N) of bulk CoO (291 K), independent of crystallographic orientation or film substrate ( alpha-Al2O3, SrTiO3, and MgO). Neutron diffraction studies show that T(B) does not track the CoO ordering temperature and, hence, that this reduction in T(B) does not arise from finite-size scaling. Instead, the ordering temperature of the CoO layers is enhanced above the bulk T(N) for layer thicknesses approximately less than or equal to 100 A due to the proximity of magnetic Fe3O4 layers.
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Affiliation(s)
- P J van der Zaag
- Philips Research Laboratories and CFT, Prof. Holstlaan 4, 5656 AA Eindhoven, The Netherlands.
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Stamps RL, Camley RE. Spin waves in antiferromagnetic thin films and multilayers: Surface and interface exchange and entire-cell effective-medium theory. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:15200-15209. [PMID: 9985582 DOI: 10.1103/physrevb.54.15200] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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50
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Abarra EN, Takano K, Hellman F, Berkowitz AE. Thermodynamic measurements of magnetic ordering in antiferromagnetic superlattices. PHYSICAL REVIEW LETTERS 1996; 77:3451-3454. [PMID: 10062223 DOI: 10.1103/physrevlett.77.3451] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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