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Puthirath Balan A, Kumar A, Scholz T, Lin Z, Shahee A, Fu S, Denneulin T, Vas J, Kovács A, Dunin-Borkowski RE, Wang HI, Yang J, Lotsch BV, Nowak U, Kläui M. Harnessing Van der Waals CrPS 4 and Surface Oxides for Nonmonotonic Preset Field Induced Exchange Bias in Fe 3GeTe 2. ACS NANO 2024; 18:8383-8391. [PMID: 38437520 DOI: 10.1021/acsnano.3c13034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
Two-dimensional van der Waals (vdW) heterostructures are an attractive platform for studying exchange bias due to their defect-free and atomically flat interfaces. Chromium thiophosphate (CrPS4), an antiferromagnetic material, possesses uncompensated magnetic spins in a single layer, rendering it a promising candidate for exploring exchange bias phenomena. Recent findings have highlighted that naturally oxidized vdW ferromagnetic Fe3GeTe2 exhibits exchange bias, attributed to the antiferromagnetic coupling of its ultrathin surface oxide layer (O-FGT) with the underlying unoxidized Fe3GeTe2. Anomalous Hall measurements are employed to scrutinize the exchange bias within the CrPS4/(O-FGT)/Fe3GeTe2 heterostructure. This analysis takes into account the contributions from both the perfectly uncompensated interfacial CrPS4 layer and the interfacial oxide layer. Intriguingly, a distinct and nonmonotonic exchange bias trend is observed as a function of temperature below 140 K. The occurrence of exchange bias induced by a "preset field" implies that the prevailing phase in the polycrystalline surface oxide is ferrimagnetic Fe3O4. Moreover, the exchange bias induced by the ferrimagnetic Fe3O4 is significantly modulated by the presence of the van der Waals antiferromagnetic CrPS4 layer, forming a heterostructure, along with additional iron oxide phases within the oxide layer. These findings underscore the intricate and complex nature of exchange bias in van der Waals heterostructures, highlighting their potential for tailored manipulation and control.
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Affiliation(s)
- Aravind Puthirath Balan
- Institute of Physics, Johannes Gutenberg University Mainz, Staudinger Weg 7, 55128 Mainz, Germany
| | - Aditya Kumar
- Institute of Physics, Johannes Gutenberg University Mainz, Staudinger Weg 7, 55128 Mainz, Germany
| | - Tanja Scholz
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Zhongchong Lin
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Aga Shahee
- Institute of Physics, Johannes Gutenberg University Mainz, Staudinger Weg 7, 55128 Mainz, Germany
| | - Shuai Fu
- Max Planck Institute for Polymer Research Mainz, Ackermannweg 10, 55128 Mainz, Germany
| | - Thibaud Denneulin
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Joseph Vas
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - András Kovács
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Hai I Wang
- Max Planck Institute for Polymer Research Mainz, Ackermannweg 10, 55128 Mainz, Germany
| | - Jinbo Yang
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Bettina V Lotsch
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Ulrich Nowak
- Department of Physics, University of Konstanz, Universitaetsstrasse 10, 78464 Konstanz, Germany
| | - Mathias Kläui
- Institute of Physics, Johannes Gutenberg University Mainz, Staudinger Weg 7, 55128 Mainz, Germany
- Centre for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim, Norway
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2
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Ukleev V, Leroy L, Mincigrucci R, De Angelis D, Fainozzi D, Khatu NN, Paltanin E, Foglia L, Bencivenga F, Luo C, Ruske F, Radu F, Svetina C, Staub U. Transient grating spectroscopy on a DyCo 5 thin film with femtosecond extreme ultraviolet pulses. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2024; 11:025101. [PMID: 38476300 PMCID: PMC10929737 DOI: 10.1063/4.0000223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 02/13/2024] [Indexed: 03/14/2024]
Abstract
Surface acoustic waves (SAWs) are excited by femtosecond extreme ultraviolet (EUV) transient gratings (TGs) in a room-temperature ferrimagnetic DyCo5 alloy. TGs are generated by crossing a pair of EUV pulses from a free electron laser with the wavelength of 20.8 nm matching the Co M-edge, resulting in a SAW wavelength of Λ = 44 nm. Using the pump-probe transient grating scheme in reflection geometry, the excited SAWs could be followed in the time range of -10 to 100 ps in the thin film. Coherent generation of TGs by ultrafast EUV pulses allows to excite SAW in any material and to investigate their couplings to other dynamics, such as spin waves and orbital dynamics. In contrast, we encountered challenges in detecting electronic and magnetic signals, potentially due to the dominance of the larger SAW signal and the weakened reflection signal from underlying layers. A potential solution for the latter challenge involves employing soft x-ray probes, albeit introducing additional complexities associated with the required grazing incidence geometry.
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Affiliation(s)
- Victor Ukleev
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-12489 Berlin, Germany
| | - Ludmila Leroy
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | | | - Dario De Angelis
- Elettra—Sincrotrone Trieste S.C.p.A., 34149 Basovizza, Trieste, Italy
| | - Danny Fainozzi
- Elettra—Sincrotrone Trieste S.C.p.A., 34149 Basovizza, Trieste, Italy
| | | | - Ettore Paltanin
- Elettra—Sincrotrone Trieste S.C.p.A., 34149 Basovizza, Trieste, Italy
| | - Laura Foglia
- Elettra—Sincrotrone Trieste S.C.p.A., 34149 Basovizza, Trieste, Italy
| | | | - Chen Luo
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-12489 Berlin, Germany
| | - Florian Ruske
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-12489 Berlin, Germany
| | - Florin Radu
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-12489 Berlin, Germany
| | | | - Urs Staub
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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3
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Kong Z, Kaminsky CJ, Groschner CK, Murphy RA, Yu Y, Husremović S, Xie LS, Erodici MP, Kim RS, Yano J, Bediako DK. Near Room-Temperature Intrinsic Exchange Bias in an Fe Intercalated ZrSe 2 Spin Glass. J Am Chem Soc 2023; 145:20041-20052. [PMID: 37646536 PMCID: PMC10510322 DOI: 10.1021/jacs.3c06967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Indexed: 09/01/2023]
Abstract
Some magnetic systems display a shift in the center of their magnetic hysteresis loop away from zero field, a phenomenon termed exchange bias. Despite the extensive use of the exchange bias effect, particularly in magnetic multilayers, for the design of spin-based memory/electronics devices, a comprehensive mechanistic understanding of this effect remains a longstanding problem. Recent work has shown that disorder-induced spin frustration might play a key role in exchange bias, suggesting new materials design approaches for spin-based electronic devices that harness this effect. Here, we design a spin glass with strong spin frustration induced by magnetic disorder by exploiting the distinctive structure of Fe intercalated ZrSe2, where Fe(II) centers are shown to occupy both octahedral and tetrahedral interstitial sites and to distribute between ZrSe2 layers without long-range structural order. Notably, we observe behavior consistent with a magnetically frustrated and multidegenerate ground state in these Fe0.17ZrSe2 single crystals, which persists above room temperature. Moreover, this magnetic frustration leads to a robust and tunable exchange bias up to 250 K. These results not only offer important insights into the effects of magnetic disorder and frustration in magnetic materials generally, but also highlight as design strategy the idea that a large exchange bias can arise from an inhomogeneous microscopic environment without discernible long-range magnetic order. In addition, these results show that intercalated TMDs like Fe0.17ZrSe2 hold potential for spintronic technologies that can achieve room temperature applications.
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Affiliation(s)
- Zhizhi Kong
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Corey J. Kaminsky
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Catherine K. Groschner
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Ryan A. Murphy
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Yun Yu
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Samra Husremović
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Lilia S. Xie
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Matthew P. Erodici
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - R. Soyoung Kim
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Junko Yano
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - D. Kwabena Bediako
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
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4
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MacManus-Driscoll JL, Wu R, Li W. Interface-related phenomena in epitaxial complex oxide ferroics across different thin film platforms: opportunities and challenges. MATERIALS HORIZONS 2023; 10:1060-1086. [PMID: 36815609 PMCID: PMC10068909 DOI: 10.1039/d2mh01527g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 02/16/2023] [Indexed: 06/18/2023]
Abstract
Interfaces in complex oxides give rise to fascinating new physical phenomena arising from the interconnected spin, lattice, charge and orbital degrees of freedom. Most commonly, interfaces are engineered in epitaxial superlattice films. Of growing interest also are epitaxial vertically aligned nanocomposite films where interfaces form by self-assembly. These two thin film forms offer different capabilities for materials tuning and have been explored largely separately from one another. Ferroics (ferroelectric, ferromagnetic, multiferroic) are among the most fascinating phenomena to be manipulated using interface effects. Hence, in this review we compare and contrast the ferroic properties that arise in these two different film forms, highlighting exemplary materials combinations which demonstrate novel, enhanced and/or emergent ferroic functionalities. We discuss the origins of the observed functionalities and propose where knowledge can be translated from one materials form to another, to potentially produce new functionalities. Finally, for the two different film forms we present a perspective on underexplored/emerging research directions.
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Affiliation(s)
| | - Rui Wu
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK.
- Spin-X Institute, School of Physics and Optoelectronics, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou 511442, China
| | - Weiwei Li
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK.
- MIIT Key Laboratory of Aerospace Information Materials and Physics, State Key Laboratory of Mechanics and Control of Mechanical Structures, College of Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
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5
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Xie X, Wang X, Wang W, Zhao X, Bai L, Chen Y, Tian Y, Yan S. Engineering Spin Configurations of Synthetic Antiferromagnet by Controlling Long-Range Oscillatory Interlayer Coupling and Neighboring Ferrimagnetic Coupling. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208275. [PMID: 36268544 DOI: 10.1002/adma.202208275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Controllable manipulation of specific spin configurations of magnetic materials is the key to constructing functional spintronic devices. Here, it is demonstrated by integrating the merits of ferromagnetic, ferrimagnetic, and antiferromagnetic spin configurations into one synthetic antiferromagnetic (SAF) heterostructure by controlling both long-range oscillatory interlayer coupling and neighboring ferrimagnetic coupling. A controllable manipulation of four types of spin configurations of the Pt/[Co/Pt/Co]/Ru/CoTb SAF heterostructures composed of ferromagnetic Co/Pt/Co and ferrimagnetic CoTb layers is successfully achieved. In particular, the compensated magnetization, enhanced anomalous Hall resistance in the remanence state, wide-temperature spin-orbit torque switching of magnetization, and high immunity to the external magnetic field are simultaneously obtained in one of the SAF heterojunctions with macroscopic interlayer antiferromagnetic coupling. This design concept of engineering spin configurations may enable efficient spin manipulation for customized memory and logic applications.
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Affiliation(s)
- Xuejie Xie
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
| | - Xiujuan Wang
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
| | - Wei Wang
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
| | - Xiaonan Zhao
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
| | - Lihui Bai
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
| | - Yanxue Chen
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
| | - Yufeng Tian
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
| | - Shishen Yan
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
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6
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Zhu W, Song C, Wang Q, Bai H, Yin S, Pan F. Anomalous displacement reaction for synthesizing above-room-temperature and air-stable vdW ferromagnet PtTe 2Ge 1/3. Natl Sci Rev 2022; 10:nwac173. [PMID: 36684515 PMCID: PMC9843128 DOI: 10.1093/nsr/nwac173] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 08/10/2022] [Indexed: 01/25/2023] Open
Abstract
Emerging van der Waals (vdW) magnets provide a paradise for the exploration of magnetism in the ultimate two-dimensional (2D) limit, and the construction of integrated spintronic devices, and have become a research frontier in the field of low-dimensional materials. To date, prototypical vdW magnets based on metals of the first transition series (e.g. V, Cr, Mn and Fe) and chalcogen elements suffer from rapid oxidation restricted by the Hard-Soft-Acid-Base principle, as well as low Curie temperatures (T C), which has become a generally admitted challenge in 2D spintronics. Here, starting from air-unstable Cr2Ge2Te6 vdW thin flakes, we synthesize Ge-embedded PtTe2 (namely PtTe2Ge1/3) with superior air stability, through the displacement reaction in the Cr2Ge2Te6/Pt bilayer. In this process, the anomalous substitution of Cr with Pt in the thermal diffusion is inverse to the metal activity order, which can be attributed to the compatibility between soft-acid (Pt) and soft-base (Te) elements. Meanwhile, the layered uniform insertion of Ge unbalances Pt-Te bonds and introduces long-range ordered ferromagnetism with perpendicular magnetic anisotropy and a Curie temperature above room temperature. Our work demonstrates the anti-metal-activity-order reaction tendency unique in 2D transition-metal magnets and boosts progress towards practical 2D spintronics.
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Affiliation(s)
- Wenxuan Zhu
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing Innovation Center for Future Chips, Tsinghua University, Beijing 100084, China
| | | | - Qian Wang
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing Innovation Center for Future Chips, Tsinghua University, Beijing 100084, China
| | - Hua Bai
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing Innovation Center for Future Chips, Tsinghua University, Beijing 100084, China
| | - Siqi Yin
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing Innovation Center for Future Chips, Tsinghua University, Beijing 100084, China
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7
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Zhang T, Zhang Y, Huang M, Li B, Sun Y, Qu Z, Duan X, Jiang C, Yang S. Tuning the Exchange Bias Effect in 2D van der Waals Ferro-/Antiferromagnetic Fe 3 GeTe 2 /CrOCl Heterostructures. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2105483. [PMID: 35238180 PMCID: PMC9009105 DOI: 10.1002/advs.202105483] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/14/2022] [Indexed: 06/01/2023]
Abstract
The exchange bias effect is extremely expected in 2D van der Waals (vdW) ferromagnetic (FM)/antiferromagnetic (AFM) heterostructures due to the high-quality interface. CrOCl possesses strong magnetic anisotropy at 2D limit, and is an ideal antiferromagnet for constructing FM/AFM heterostructures to explore the exchange bias effect. Here, the exchange bias effect in Fe3 GeTe2 (FGT)/CrOCl heterostructures through both anomalous Hall effect (AHE) and reflective magnetic circular dichroism (RMCD) measurements is studied. In the AHE measurements, the exchange bias field (HEB ) at 3 K exhibits a distinct increase from ≈150 Oe to ≈450 Oe after air exposure, and such variation is attributed to the formation of an oxidized layer in FGT by analyzing the cross-sectional microstructure. The HEB is successfully tuned by changing the FGT/CrOCl thickness and the cooling field. Furthermore, a larger HEB of ≈750 Oe at 1.7 K in FGT/CrOCl heterostructure through RMCD measurements is observed, and it is proposed that the larger HEB in RMCD measurements is related to the distribution of uncompensated spins at the interface. This work reveals several intriguing phenomena of the exchange bias effect in 2D vdW magnetic systems, which paves the way for the study of related spintronic devices.
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Affiliation(s)
- Tianle Zhang
- School of Materials Science and EngineeringBeihang UniversityBeijing100191P. R. China
| | - Yujun Zhang
- Department of PhysicsSouthern University of Science and TechnologyShenzhenGuangdong518055P. R. China
| | - Mingyuan Huang
- Department of PhysicsSouthern University of Science and TechnologyShenzhenGuangdong518055P. R. China
| | - Bo Li
- Hunan Key Laboratory of Two‐Dimensional MaterialsSchool of Physics and ElectronicsHunan UniversityChangshaHunan410082P. R. China
| | - Yinghui Sun
- Beijing Key Laboratory for Magneto‐Photoelectrical Composite and Interface ScienceSchool of Mathematics and PhysicsUniversity of Science and Technology BeijingBeijing100083P. R. China
| | - Zhe Qu
- Anhui Key Laboratory of Condensed Matter Physics at Extreme ConditionsHigh Magnetic Field LaboratoryChinese Academy of SciencesHefeiAnhui230031P. R. China
| | - Xidong Duan
- State Key Laboratory for Chemo/Biosensing and ChemometricsCollege of Chemistry and Chemical EngineeringHunan UniversityChangshaHunan419982P. R. China
| | - Chengbao Jiang
- School of Materials Science and EngineeringBeihang UniversityBeijing100191P. R. China
| | - Shengxue Yang
- School of Materials Science and EngineeringBeihang UniversityBeijing100191P. R. China
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8
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Huang J, Zhang D, Liu J, Dou H, Wang H. Double-Exchange Bias Modulation under Horizontal and Perpendicular Field Directions by 3D Nanocomposite Design. ACS APPLIED MATERIALS & INTERFACES 2021; 13:50141-50148. [PMID: 34644494 DOI: 10.1021/acsami.1c14699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Exchange bias (EB) presents the interfacial coupling between ferromagnetic (FM) and antiferromagnetic (AFM) phases, which could be applied for high-density data storage and magnetic recording. In thin films, the EB effect could be realized in either a FM/AFM multilayer structure or a FM/AFM vertically aligned nanocomposite (VAN) form, which allows the interfacial coupling tuning along the horizontal or perpendicular directions, respectively. Here, to combine the schemes of multilayer and VAN structures, a new 3D nanocomposite has been designed, which is La0.7Sr0.3MnO3 (LSMO)/NiO VAN layers with inserted LSMO or NiO layers. Such a 3D nanocomposite structure provides a great platform to tailor the EB effect along both horizontal and perpendicular directions. Specifically, the sample with a NiO interlayer exhibits the highest EB field (HEB) of 350 Oe and 475 Oe under in-plane and out-of-plane field, respectively. Furthermore, the HEB value and Curie temperature (Tc) can be tuned by different 3D nanostructures. This work demonstrates the double EB modulation with the designed 3D nanostructures as a new route toward advanced magnetic data storage and spintronic devices.
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Affiliation(s)
- Jijie Huang
- School of Materials, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
| | - Di Zhang
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Juncheng Liu
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Hongyi Dou
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Haiyan Wang
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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9
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Large Perpendicular Exchange Energy in TbxCo100−x/Cu(t)/[Co/Pt]2 Heterostructures. MAGNETOCHEMISTRY 2021. [DOI: 10.3390/magnetochemistry7110141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In order to realize a perpendicular exchange bias for applications, a robust and tunable exchange bias is required for spintronic applications. Here, we show the perpendicular exchange energy (PEE) in the TbxCo100−x/Cu/[Co/Pt]2 heterostructures. The structure consists of amorphous ferrimagnetic Tb–Co alloy films and ferromagnetic Co/Pt multilayers. The dependence of the PEE on the interlayer thickness of Cu and the composition of Tb–Co were analyzed. We demonstrate that the PEE can be controlled by changing the Cu interlayer thickness of 0.2 < tCu < 0.3 (nm). We found that PEE reaches a maximum value (σPw = 1 erg/cm2) at around x = 24%. We, therefore, realize the mechanism of PEE in the TbxCo100−x/Cu/[Co/Pt]2 heterostructures. We observe two competing mechanisms—one leading to an increase and the other to a decrease—which corresponds to the effect of Tb content on saturation magnetization and the coercivity of heterostructures. Sequentially, our findings show possibilities for both pinned layers in spintronics and memory device applications by producing large PEE and controlled PEE by Cu thickness, based on TbxCo100−x/Cu/[Co/Pt]2 heterostructures.
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10
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González JA, Andrés JP, López Antón R. Applied Trends in Magnetic Rare Earth/Transition Metal Alloys and Multilayers. SENSORS (BASEL, SWITZERLAND) 2021; 21:5615. [PMID: 34451055 PMCID: PMC8402375 DOI: 10.3390/s21165615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/14/2021] [Accepted: 08/17/2021] [Indexed: 11/16/2022]
Abstract
Ferrimagnetic thin films formerly played a very important role in the development of information storage technology. Now they are again at the forefront of the rising field of spintronics. From new, more efficient magnetic recording media and sensors based on spin valves to the promising technologies envisaged by all-optical switching, ferrimagnets offer singular properties that deserve to be studies both from the point of view of fundamental physics and for applications. In this review, we will focus on ferrimagnetic thin films based on the combination of rare earths (RE) and transition metals (TM).
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Affiliation(s)
- Juan Antonio González
- Instituto Regional de Investigación Científica Aplicada (IRICA), Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain; (J.A.G.); (J.P.A.)
- Departamento de Física Aplicada, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
| | - Juan Pedro Andrés
- Instituto Regional de Investigación Científica Aplicada (IRICA), Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain; (J.A.G.); (J.P.A.)
- Departamento de Física Aplicada, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
| | - Ricardo López Antón
- Instituto Regional de Investigación Científica Aplicada (IRICA), Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain; (J.A.G.); (J.P.A.)
- Departamento de Física Aplicada, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
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11
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Seifert TS, Martens U, Radu F, Ribow M, Berritta M, Nádvorník L, Starke R, Jungwirth T, Wolf M, Radu I, Münzenberg M, Oppeneer PM, Woltersdorf G, Kampfrath T. Frequency-Independent Terahertz Anomalous Hall Effect in DyCo 5 , Co 32 Fe 68 , and Gd 27 Fe 73 Thin Films from DC to 40 THz. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2007398. [PMID: 33656190 DOI: 10.1002/adma.202007398] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 12/21/2020] [Indexed: 06/12/2023]
Abstract
The anomalous Hall effect (AHE) is a fundamental spintronic charge-to-charge-current conversion phenomenon and closely related to spin-to-charge-current conversion by the spin Hall effect. Future high-speed spintronic devices will crucially rely on such conversion phenomena at terahertz (THz) frequencies. Here, it is revealed that the AHE remains operative from DC up to 40 THz with a flat frequency response in thin films of three technologically relevant magnetic materials: DyCo5 , Co32 Fe68 , and Gd27 Fe73 . The frequency-dependent conductivity-tensor elements σxx and σyx are measured, and good agreement with DC measurements is found. The experimental findings are fully consistent with ab initio calculations of σyx for CoFe and highlight the role of the large Drude scattering rate (≈100 THz) of metal thin films, which smears out any sharp spectral features of the THz AHE. Finally, it is found that the intrinsic contribution to the THz AHE dominates over the extrinsic mechanisms for the Co32 Fe68 sample. The results imply that the AHE and related effects such as the spin Hall effect are highly promising ingredients of future THz spintronic devices reliably operating from DC to 40 THz and beyond.
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Affiliation(s)
- Tom S Seifert
- Department of Physics, Freie Universität Berlin, Berlin, 14195, Germany
- Department of Physical Chemistry, Fritz-Haber-Institute of the Max-Planck-Society, Berlin, 14195, Germany
| | - Ulrike Martens
- Institute of Physics, University of Greifswald, Greifswald, 17489, Germany
| | - Florin Radu
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, Berlin, 12489, Germany
| | - Mirkow Ribow
- Institute of Physics, Martin-Luther Universität Halle-Wittenberg, Halle (Saale), 06120, Germany
| | - Marco Berritta
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, Uppsala, SE-75120, Sweden
| | - Lukáš Nádvorník
- Faculty of Mathematics and Physics, Charles University, Ke Kalovu 2027/3, Prague, 12116, Czech Republic
| | | | - Tomas Jungwirth
- Institute of Physics, Czech Academy of Sciences, Cukrovarnicka 10, Praha, 6, 162 00, Czech Republic
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Martin Wolf
- Department of Physical Chemistry, Fritz-Haber-Institute of the Max-Planck-Society, Berlin, 14195, Germany
| | - Ilie Radu
- Department of Physics, Freie Universität Berlin, Berlin, 14195, Germany
- Max-Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Str. 2A, Berlin, 12489, Germany
| | - Markus Münzenberg
- Institute of Physics, University of Greifswald, Greifswald, 17489, Germany
| | - Peter M Oppeneer
- Institute of Physics, Martin-Luther Universität Halle-Wittenberg, Halle (Saale), 06120, Germany
| | - Georg Woltersdorf
- Institute of Physics, Martin-Luther Universität Halle-Wittenberg, Halle (Saale), 06120, Germany
| | - Tobias Kampfrath
- Department of Physics, Freie Universität Berlin, Berlin, 14195, Germany
- Department of Physical Chemistry, Fritz-Haber-Institute of the Max-Planck-Society, Berlin, 14195, Germany
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12
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Heigl M, Vogler C, Mandru AO, Zhao X, Hug HJ, Suess D, Albrecht M. Microscopic Origin of Magnetization Reversal in Nanoscale Exchange-Coupled Ferri/Ferromagnetic Bilayers: Implications for High Energy Density Permanent Magnets and Spintronic Devices. ACS APPLIED NANO MATERIALS 2020; 3:9218-9225. [PMID: 33005879 PMCID: PMC7522967 DOI: 10.1021/acsanm.0c01835] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 08/05/2020] [Indexed: 06/11/2023]
Abstract
Giant exchange bias shifts of several Tesla have been reported in ferrimagnetic/ferromagnetic bilayer systems, which could be highly beneficial for contemporary high energy density permanent magnets and spintronic devices. However, the lack of microscopic studies of the reversal owing to the difficulty of measuring few nanometer-wide magnetic structures in high fields precludes the assessment of the lateral size of the inhomogeneity in relation to the intended application. In this study, the magnetic reversal process of nanoscale exchange-coupled bilayer systems, consisting of a ferrimagnetic TbFeCo alloy layer and a ferromagnetic [Co/Ni/Pt] N multilayer, was investigated. In particular, minor loop measurements, probing solely on the reversal characteristics of the softer ferromagnetic layer, reveal two distinct reversal mechanisms, which depend critically on the thickness of the ferromagnetic layer. For thick layers, irreversible switching of the macroscopic minor loop is observed. The underlying microscopic origin of this reversal process was studied in detail by high-resolution magnetic force microscopy, showing that the reversal is triggered by in-plane domain walls propagating through the ferromagnetic layer. In contrast, thin ferromagnetic layers show a hysteresis-free reversal, which is nucleation-dominated due to grain-to-grain variations in magnetic anisotropy of the Co/Ni/Pt multilayer and an inhomogeneous exchange coupling with the magnetically hard TbFeCo layer, as confirmed by micromagnetic simulations.
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Affiliation(s)
- Michael Heigl
- Institute
of Physics, University of Augsburg, Augsburg 86159, Germany
| | | | - Andrada-Oana Mandru
- Empa−Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf CH-8600, Switzerland
| | - Xue Zhao
- Empa−Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf CH-8600, Switzerland
| | - Hans Josef Hug
- Empa−Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf CH-8600, Switzerland
- Department
of Physics, University of Basel, Basel CH-4056, Switzerland
| | - Dieter Suess
- Christian
Doppler Laboratory for Advanced Magnetic Sensing and Materials, Faculty
of Physics, University of Vienna, Vienna 1090, Austria
| | - Manfred Albrecht
- Institute
of Physics, University of Augsburg, Augsburg 86159, Germany
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13
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Hu G, Zhu Y, Xiang J, Yang TY, Huang M, Wang Z, Wang Z, Liu P, Zhang Y, Feng C, Hou D, Zhu W, Gu M, Hsu CH, Chuang FC, Lu Y, Xiang B, Chueh YL. Antisymmetric Magnetoresistance in a van der Waals Antiferromagnetic/Ferromagnetic Layered MnPS 3/Fe 3GeTe 2 Stacking Heterostructure. ACS NANO 2020; 14:12037-12044. [PMID: 32885948 DOI: 10.1021/acsnano.0c05252] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The presence of two-dimensional (2D) layer-stacking heterostructures that can efficiently tune the interface properties by stacking desirable materials provides a platform to investigate some physical phenomena, such as the proximity effect and magnetic exchange coupling. Here, we report the observation of antisymmetric magnetoresistance in a van der Waals (vdW) antiferromagnetic/ferromagnetic (AFM/FM) heterostructure of MnPS3/Fe3GeTe2 when the temperature is below the Neel temperature of MnPS3. Distinguished from two resistance states in conventional giant magnetoresistance, the magnetoresistance in the MnPS3/Fe3GeTe2 heterostructure exhibits three states, of high, intermediate, and low resistance. This antisymmetric magnetoresistance spike is determined by an unsynchronized magnetic switching between the AFM/FM interface layer and the bulk of Fe3GeTe2 during magnetization reversal. Our work highlights that the artificial vdW stacking structure holds potential to explore some physical phenomena and spintronic device applications.
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Affiliation(s)
- Guojing Hu
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yuanmin Zhu
- SUSTech Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology of China, Shenzhen, Guangdong 518055, China
- Department of Materials Science and Engineering, Southern University of Science and Technology of China, Shenzhen, Guangdong 518055, China
| | - Junxiang Xiang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Tzu-Yi Yang
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
- Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Meng Huang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhe Wang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhi Wang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
- Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei 230026, China
| | - Ping Liu
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ying Zhang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
- Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei 230026, China
| | - Chao Feng
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Dazhi Hou
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wenguang Zhu
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Meng Gu
- Department of Materials Science and Engineering, Southern University of Science and Technology of China, Shenzhen, Guangdong 518055, China
| | - Chia-Hsiu Hsu
- Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
| | - Feng-Chuan Chuang
- Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Physics Division, National Center for Theoretical Sciences, Hsinchu 30013, Taiwan
| | - Yalin Lu
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
- Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei 230026, China
| | - Bin Xiang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026, China
- Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei 230026, China
| | - Yu-Lun Chueh
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
- Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
- Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan
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14
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Chen K, Lott D, Philippi-Kobs A, Weigand M, Luo C, Radu F. Observation of compact ferrimagnetic skyrmions in DyCo 3 film. NANOSCALE 2020; 12:18137-18143. [PMID: 32852506 DOI: 10.1039/d0nr02947e] [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
Owing to the experimental discovery of magnetic skyrmions stabilized by the Dzyaloshinskii-Moriya and/or dipolar interactions in thin films, there is a recent upsurge of interest in magnetic skyrmions with antiferromagnetic spins in order to overcome the fundamental limitations inherent with skyrmions in ferromagnetic materials. Here, we report on the observation of compact ferrimagnetic skyrmions for the class of amorphous alloys consisting of 4f rare-earth and 3d transition-metal elements with perpendicular magnetic anisotropy, using a DyCo3 film, that are identified by combining X-ray magnetic scattering, scanning transmission X-ray microscopy, and Hall transport technique. These skyrmions, with antiparallel aligned Dy and Co magnetic moments and a characteristic core radius of about 40 nm, are formed during the nucleation and annihilation of the magnetic maze-like domain pattern exhibiting a topological Hall effect contribution. Our findings provide a promising route for fundamental research in the field of ferrimagnetic/antiferromagnetic spintronics towards practical applications.
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Affiliation(s)
- K Chen
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
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15
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Zheng G, Xie WQ, Albarakati S, Algarni M, Tan C, Wang Y, Peng J, Partridge J, Farrar L, Yi J, Xiong Y, Tian M, Zhao YJ, Wang L. Gate-Tuned Interlayer Coupling in van der Waals Ferromagnet Fe_{3}GeTe_{2} Nanoflakes. PHYSICAL REVIEW LETTERS 2020; 125:047202. [PMID: 32794802 DOI: 10.1103/physrevlett.125.047202] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 05/19/2020] [Accepted: 06/22/2020] [Indexed: 06/11/2023]
Abstract
The weak interlayer coupling in van der Waals (vdW) magnets has confined their application to two dimensional (2D) spintronic devices. Here, we demonstrate that the interlayer coupling in a vdW magnet Fe_{3}GeTe_{2} (FGT) can be largely modulated by a protonic gate. With the increase of the protons intercalated among vdW layers, interlayer magnetic coupling increases. Because of the existence of antiferromagnetic layers in FGT nanoflakes, the increasing interlayer magnetic coupling induces exchange bias in protonated FGT nanoflakes. Most strikingly, a rarely seen zero-field cooled (ZFC) exchange bias with very large values (maximally up to 1.2 kOe) has been observed when higher positive voltages (V_{g}≥4.36 V) are applied to the protonic gate, which clearly demonstrates that a strong interlayer coupling is realized by proton intercalation. Such strong interlayer coupling will enable a wider range of applications for vdW magnets.
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Affiliation(s)
- Guolin Zheng
- School of Science, RMIT University, Melbourne VIC 3001, Australia
| | - Wen-Qiang Xie
- Department of Physics, South China University of Technology, Guangzhou 510640, China
| | | | - Meri Algarni
- School of Science, RMIT University, Melbourne VIC 3001, Australia
| | - Cheng Tan
- School of Science, RMIT University, Melbourne VIC 3001, Australia
| | - Yihao Wang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences (CAS), Hefei 230031, Anhui, China
| | - Jingyang Peng
- School of Science, RMIT University, Melbourne VIC 3001, Australia
| | - James Partridge
- School of Science, RMIT University, Melbourne VIC 3001, Australia
| | - Lawrence Farrar
- School of Science, RMIT University, Melbourne VIC 3001, Australia
| | - Jiabao Yi
- Global Innovative Center for Advanced Nanomaterials, School of Engineering, University of Newcastle, Callaghan NSW 2308, Australia
| | - Yimin Xiong
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences (CAS), Hefei 230031, Anhui, China
| | - Mingliang Tian
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences (CAS), Hefei 230031, Anhui, China
- Department of Physics, School of Physics and Materials Science, Anhui University, Hefei 230601, Anhui, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yu-Jun Zhao
- Department of Physics, South China University of Technology, Guangzhou 510640, China
| | - Lan Wang
- School of Science, RMIT University, Melbourne VIC 3001, Australia
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16
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Srivastava PK, Hassan Y, Ahn H, Kang B, Jung SG, Gebredingle Y, Joe M, Abbas MS, Park T, Park JG, Lee KJ, Lee C. Exchange Bias Effect in Ferro-/Antiferromagnetic van der Waals Heterostructures. NANO LETTERS 2020; 20:3978-3985. [PMID: 32330042 DOI: 10.1021/acs.nanolett.0c01176] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The recent discovery of magnetic van der Waals (vdW) materials provides a platform to answer fundamental questions on the two-dimensional (2D) limit of magnetic phenomena and applications. An important question in magnetism is the ultimate limit of the antiferromagnetic layer thickness in ferromagnetic (FM)/antiferromagnetic (AFM) heterostructures to observe the exchange bias (EB) effect, of which origin has been subject to a long-standing debate. Here, we report that the EB effect is maintained down to the atomic bilayer of AFM in the FM (Fe3GeTe2)/AFM (CrPS4) vdW heterostructure, but it vanishes at the single-layer limit. Given that CrPS4 is of A-type AFM and, thus, the bilayer is the smallest unit to form an AFM, this result clearly demonstrates the 2D limit of EB; only one unit of AFM ordering is sufficient for a finite EB effect. Moreover, the semiconducting property of AFM CrPS4 allows us to electrically control the exchange bias, providing an energy-efficient knob for spintronic devices.
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Affiliation(s)
- Pawan Kumar Srivastava
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Yasir Hassan
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Hyobin Ahn
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Byunggil Kang
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Soon-Gil Jung
- Center for Quantum Materials and Superconductivity (CQMS), Sungkyunkwan University, Suwon 16419, Republic of Korea
- Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Yisehak Gebredingle
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Minwoong Joe
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | | | - Tuson Park
- Center for Quantum Materials and Superconductivity (CQMS), Sungkyunkwan University, Suwon 16419, Republic of Korea
- Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Je-Geun Park
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Republic of Korea
| | - Changgu Lee
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Republic of Korea
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17
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Das M, Roy S, Mahalingam K, Ganesan V, Mandal P. Anomalous magnetic properties of RCrTiO 5 (R = Dy and Ho) compounds. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:035802. [PMID: 31561240 DOI: 10.1088/1361-648x/ab48bb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We have investigated the nature of magnetic ground state of RCrTiO5 (R = Dy and Ho) through dc magnetization and heat capacity measurements. Due to the strong competition between the Cr3+ and R 3+ sublattice moments, several intriguing phenomena have been observed when the magnetic state is probed at low field. In both the systems, the Cr3+ sublattice undergoes a long-range antiferromagnetic ordering below ∼139 K with a weak ferromagnetic (FM) moment perpendicular to c axis as evident from the hysteresis in M(H) curve. At low fields ([Formula: see text]150 Oe), the zero-field-cooled magnetization shows that the FM component of Cr3+ spin and R 3+ moments align in the opposite direction with respect to each other and the net moment aligns in the opposite direction to the applied field in the temperature range 136-16 K for DyCrTiO5 and below 128 K for HoCrTiO5. For both the samples, the strong coupling between the two magnetic sublattices is manifested in the temperature dependence of coercive field. Another interesting phenomenon, the spin reorientation transition, has been observed below [Formula: see text] K, where the easy axis of FM moment of Cr3+ starts to rotate from one crystallographic axis toward another in DyCrTiO5 but no such transition has been observed in HoCrTiO5. The other members of RCrTiO5 series do not show such kinds of interesting magnetic properties.
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Affiliation(s)
- Moumita Das
- Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Calcutta 700064, India
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18
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Luo C, Ryll H, Back CH, Radu F. X-ray magnetic linear dichroism as a probe for non-collinear magnetic state in ferrimagnetic single layer exchange bias systems. Sci Rep 2019; 9:18169. [PMID: 31796813 PMCID: PMC6890699 DOI: 10.1038/s41598-019-54356-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 11/11/2019] [Indexed: 11/09/2022] Open
Abstract
Ferrimagnetic alloys are extensively studied for their unique magnetic properties leading to possible applications in perpendicular magnetic recording, due to their deterministic ultrafast switching and heat assisted magnetic recording capabilities. On a prototype ferrimagnetic alloy we demonstrate fascinating properties that occur close to a critical temperature where the magnetization is vanishing, just as in an antiferromagnet. From the X-ray magnetic circular dichroism measurements, an anomalous 'wing shape' hysteresis loop is observed slightly above the compensation temperature. This bears the characteristics of an intrinsic exchange bias effect, referred to as atomic exchange bias. We further exploit the X-ray magnetic linear dichroism (XMLD) contrast for probing non-collinear states which allows us to discriminate between two main reversal mechanisms, namely perpendicular domain wall formation versus spin-flop transition. Ultimately, we analyze the elemental magnetic moments for the surface and the bulk parts, separately, which allows to identify in the phase diagram the temperature window where this effect takes place. Moreover, we suggests that this effect is a general phenomenon in ferrimagnetic thin films which may also contribute to the understanding of the mechanism behind the all optical switching effect.
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Affiliation(s)
- Chen Luo
- Helmholtz-Zentrum-Berlin für Materialen und Energie, Albert-Einstein-Strasse 15, 12489, Berlin, Germany. .,Institute of Experimental and Applied Physics, University of Regensburg, 93053, Regensburg, Germany. .,Institute of Experimental Physics of Functional Spin Systems, Technical University Munich, James-Franck-Str. 1, 85748, Garching b. München, Germany.
| | - Hanjo Ryll
- Helmholtz-Zentrum-Berlin für Materialen und Energie, Albert-Einstein-Strasse 15, 12489, Berlin, Germany
| | - Christian H Back
- Institute of Experimental and Applied Physics, University of Regensburg, 93053, Regensburg, Germany.,Institute of Experimental Physics of Functional Spin Systems, Technical University Munich, James-Franck-Str. 1, 85748, Garching b. München, Germany
| | - Florin Radu
- Helmholtz-Zentrum-Berlin für Materialen und Energie, Albert-Einstein-Strasse 15, 12489, Berlin, Germany.
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19
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Salaheldeen M, Vega V, Caballero-Flores R, Prida VM, Fernández A. Influence of nanoholes array geometrical parameters on magnetic properties of Dy-Fe antidot thin films. NANOTECHNOLOGY 2019; 30:455703. [PMID: 31362273 DOI: 10.1088/1361-6528/ab36cc] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nanoscale artificially engineered spintronic materials could be used to enlarge the storage density of magnetic recording media. For this purpose, magnetic nanostructures such as antidot arrays exhibiting high uniaxial magnetic anisotropy are new contestants in the field of ultrahigh density magnetic data storage devices. In this context, we focus on the synthesis of nanostructured magnetic materials consisting of Dy-Fe alloyed antidot thin films, deposited onto the surface of nanoporous alumina membranes served as patterned templates. Noticeable variations of in the in-plane magnetic anisotropy have been observed by modifying the layer thickness at both microscopic and macroscopic scales. The microscopic magnetic properties have been locally studied by Nano-MOKE magnetometry. For thinner antidot samples with 15, 20 and 25 nm in thickness, a tri-axial in-plane magnetic anisotropy has been detected. Meanwhile, for thicker antidot samples (40-60 nm of layer thickness), an in-plane uniaxial magnetic anisotropy has been noted. We attribute these changes in the magnetic anisotropy to the strong correlation between the edge-to-edge distance among adjacent nanoholes, W, and the local magnetic anisotropy of antidot samples. The effective magnetic anisotropy exhibits an unexpected crossover from the in-plane to out-of-plane direction due to the increasing of the effective perpendicular magnetic anisotropy with varying the layer thickness of antidot thin films. Therefore, we detected a critical layer thickness, t = 25 nm for the Dy-Fe alloy antidot arrays, at which the appearance of the perpendicular magnetization is observed. Furthermore, an enhancement in the Curie temperature of the antidot arrays compared to the continuous thin films has been obtained. We attribute these effects to the complex magnetization reversal processes and the high thermal stability of the hexagonal structure of antidot arrays. These findings can be of high interest for the development of novel magnetic sensors and for thermo-magnetic recording patterned media based on template-assisted deposition techniques.
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Affiliation(s)
- M Salaheldeen
- Physics Department, Faculty of Science, Sohag University, 82524 Sohag, Egypt. Depto. Física, Universidad de Oviedo, C/Federico García Lorca 18, E-33007 Oviedo, Asturias, Spain
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20
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Abstract
Magnetic materials are usually classified into a distinct category such as diamagnets, paramagnets or ferromagnets. The enormous progress in materials science allows one nowadays, however, to change the magnetic nature of an element in a material. Gold, in bulk form, is traditionally a diamagnet. But in a ferromagnetic environment, it can adopt an induced ferromagnetic moment. Moreover, the growth of gold under certain conditions may lead to a spontaneous ferromagnetic or paramagnetic response. Here, we report on paramagnetic gold in a highly disordered Au-Ni-O alloy and focus on the unusual magnetic response. Such materials are mainly considered for plasmonic applications. Thin films containing Au, Ni and NiO are fabricated by co-deposition of Ni and Au in a medium vacuum of 2 × 10-2 mbar. As a result, Au is in a fully disordered state forming in some cases isolated nanocrystallites of up to 4 nm in diameter as revealed by high resolution transmission electron microscopy. The disorder and the environment, which is rich in oxygen, lead to remarkable magnetic properties of Au: an induced ferromagnetic and a paramagnetic state. This can be proven by measuring the x-ray magnetic circular dichroism. Our experiments show a way to establish and monitor Au paramagnetism in alloys.
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21
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Wu R, Yun C, Wang X, Lu P, Li W, Lin Y, Choi EM, Wang H, MacManus-Driscoll JL. All-Oxide Nanocomposites to Yield Large, Tunable Perpendicular Exchange Bias above Room Temperature. ACS APPLIED MATERIALS & INTERFACES 2018; 10:42593-42602. [PMID: 30394088 DOI: 10.1021/acsami.8b14635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In all-oxide-based spintronic devices, large exchange bias effect with robustness against temperature fluctuation and compatibility with perpendicular magnetic recording is highly desired. In this work, rock-salt antiferromagnetic NiO with a Néel temperature ( TN) of ∼525 K and spinel ferrimagnetic NiFe2O4 with a high Curie temperature, TC, ≈ 790 K and TC > TN were chosen as compatible materials to form a well-phase-separated, vertically aligned nanocomposite thin film. In this nanoengineered thin film, an exchange bias effect with a blocking temperature far above room temperature has been achieved. A large perpendicular exchange bias field of up to 0.91 kOe with an interfacial exchange energy density of 0.11-0.34 erg/cm2 was obtained at room temperature. It was also demonstrated that the exchange bias effect can be easily tuned by changing the alignment of the magnetic moments in the NiO phase using substrates of different crystalline orientations and by changing the microstructure of the film with substrates of different lattice parameters. The results demonstrate that proper choice of the phases (including use of nonperovskite compositions) and careful strain engineering and nanostructure engineering makes oxide nanocomposites strong potential candidate systems for next generation spintronic devices.
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Affiliation(s)
- Rui Wu
- Department of Materials Science & Metallurgy , University of Cambridge , Cambridge CB3 0FS , U.K
| | - Chao Yun
- Department of Materials Science & Metallurgy , University of Cambridge , Cambridge CB3 0FS , U.K
| | - Xuejing Wang
- Materials Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Ping Lu
- Sandia National Laboratories , Albuquerque , New Mexico 87185 , United States
| | - Weiwei Li
- Department of Materials Science & Metallurgy , University of Cambridge , Cambridge CB3 0FS , U.K
| | - Yisong Lin
- Department of Materials Science & Metallurgy , University of Cambridge , Cambridge CB3 0FS , U.K
| | - Eun-Mi Choi
- Department of Materials Science & Metallurgy , University of Cambridge , Cambridge CB3 0FS , U.K
| | - Haiyan Wang
- Materials Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
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22
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Wide-range tuning of interfacial exchange coupling between ferromagnetic Au/Co and ferrimagnetic Tb/Fe(Co) multilayers. Sci Rep 2018; 8:16911. [PMID: 30442894 PMCID: PMC6237983 DOI: 10.1038/s41598-018-35042-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 10/26/2018] [Indexed: 12/05/2022] Open
Abstract
The ability to perform wide-range tuning of the magnetic field required to switch the magnetization of ferromagnetic layers with perpendicular magnetic anisotropy is of great importance for many applications. We show that, for (Au/Co)2(3) multilayers, this field can be changed from minus several kOe to plus several kOe because of changes to the coupling with a ferrimagnetic multilayer [either (Tb/Fe)6 or (Tb/Co)6] across a Au spacer (either homogeneous 1 nm thick or wedge-shaped). The adjustable parameters are the ratio of sublayer thicknesses of the ferrimagnet and the sequence of layers around the Au spacer. The change of the sequence from Co/Au/Co to Tb/Au/Co is accompanied by both the reduction of the interaction energy and the change of the magnetic field sign necessary to switch the magnetization of ferromagnetic multilayers. For a 1 nm thick Au spacer this fields change from positive (negative) to negative (positive) if the ferrimagnet is dominated by the transition metal (rare earth) as a result of its composition. The characteristic oscillatory behavior of RKKY-like coupling is demonstrated using a system with a wedge-shaped Au spacer.
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23
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Design and Synthesis of an Artificial Perpendicular Hard Ferrimagnet with High Thermal and Magnetic Field Stabilities. Sci Rep 2017; 7:16990. [PMID: 29208959 PMCID: PMC5717302 DOI: 10.1038/s41598-017-16761-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/16/2017] [Indexed: 11/29/2022] Open
Abstract
It is of great fundamental and practical interest to develop effective means of modulating the magnetic hystereses of magnetic materials and their heterostructures. A notable example is the exchange bias (EB) effect between an antiferromagnet or ferrimagnet and a ferromagnet, which has been widely employed to manipulate magnetic anisotropy in spintronic devices and artificial magnets. Here, we report the design, synthesis and characterization of a synthetic perpendicularly-magnetized ferrimagnet based on [Mn2.9Ga/Co2MnSi]n superlattices, which attains thermal stability above 400 K and a coercive field up to 45 kOe through a mechanism of magnetic compensation. The structure is incorporated into a prototype Heusler alloy and MgO barrier based magnetic tunnel junction, which demonstrates high dynamic range linear field responses and an unusual in-plane EB effect. With increasing temperature, the coercive field reaches beyond 70 kOe at 400 K in this device due to the increasing degree of magnetic moment compensation in the superlattice. The results demonstrate that the compensation mechanism can be utilized to achieve simultaneous thermal robustness and high coercivity in realistic spintronic devices.
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24
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Observation of an atomic exchange bias effect in DyCo4 film. Sci Rep 2015; 5:18377. [PMID: 26675537 PMCID: PMC4682085 DOI: 10.1038/srep18377] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 11/03/2015] [Indexed: 11/30/2022] Open
Abstract
The fundamental important and technologically widely employed exchange bias effect occurs in general in bilayers of magnetic thin films consisting of antiferromagnetic and ferromagnetic layers where the hard magnetization behavior of an antiferromagnetic thin film causes a shift in the magnetization curve of a soft ferromagnetic film. The minimization of the single magnetic grain size to increase the storage density and the subsequent demand for magnetic materials with very high magnetic anisotropy requires a system with high HEB. Here we report an extremely high HEB of 4 Tesla observed in a single amorphous DyCo4 film close to room temperature. The origin of the exchange bias can be associated with the variation of the magnetic behavior from the surface towards the bulk part of the film revealed by X-ray absorption spectroscopy and X-ray magnetic circular dichroism techniques utilizing the bulk sensitive transmission and the surface sensitive total electron yield modes. The competition between the atomic exchange coupling in the single film and the Zeeman interaction lead to an intrinsic exchanged coupled system and the so far highest exchange bias effect HEB = 4 Tesla reported in a single film, which is accommodated by a partial domain wall formation.
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25
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Kachel T, Eggenstein F, Follath R. A soft X-ray plane-grating monochromator optimized for elliptical dipole radiation from modern sources. JOURNAL OF SYNCHROTRON RADIATION 2015; 22:1301-1305. [PMID: 26289284 PMCID: PMC4787842 DOI: 10.1107/s1600577515010826] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 06/04/2015] [Indexed: 06/01/2023]
Abstract
A new but yet well proven way of making elliptically polarized dipole radiation from the BESSY II storage ring applicable to the SX700-type collimated plane-grating monochromator PM3 is described. It is shown that due to the limited vertical acceptance of the grating a simple use of vertical apertures is not possible in this case. Rather, deflecting the beam upwards or downwards by rotating the vertically collimating toroidal mirror M1 around the light axis leads to excellent performance. The resulting detuning of the photon energy can be taken into account by a readjustment of the monochromator internal plane mirror M2. The energy resolution of the beamline is not affected by the non-zero `roll' of the collimating mirror.
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Affiliation(s)
- Torsten Kachel
- Institute for Methods and Instrumentation in Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - Frank Eggenstein
- Institute for Nanometer Optics and Technology, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - Rolf Follath
- Beamline Optics Group, Paul Scherrer Institute, 5232 Villigen, Switzerland
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26
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Interfacial exchange coupling and magnetization reversal in perpendicular [Co/Ni]N/TbCo composite structures. Sci Rep 2015; 5:10863. [PMID: 26074295 PMCID: PMC4466588 DOI: 10.1038/srep10863] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 05/01/2015] [Indexed: 11/09/2022] Open
Abstract
Interfacial exchange coupling and magnetization reversal characteristics in the perpendicular heterostructures consisting of an amorphous ferrimagnetic (FI) TbxCo(100-x) alloy layer exchange-coupled with a ferromagnetic (FM) [Co/Ni]N multilayer have been investigated. As compared with pure TbxCo(100-x) alloy, the magnetization compensation composition of the heterostructures shift to a higher Tb content, implying Co/Ni also serves to compensate the Tb moment in TbCo layer. The net magnetization switching field Hc⊥ and interlayer interfacial coupling field Hex, are not only sensitive to the magnetization and thickness of the switched TbxCo(100-x) or [Co/Ni]N layer, but also to the perpendicular magnetic anisotropy strength of the pinning layer. By tuning the layer structure we achieve simultaneously both large Hc⊥ = 1.31 T and Hex = 2.19 T. These results, in addition to the fundamental interest, are important to understanding of the interfacial coupling interaction in the FM/FI heterostructures, which could offer the guiding of potential applications in heat-assisted magnetic recording or all-optical switching recording technique.
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27
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Abrudan R, Brüssing F, Salikhov R, Meermann J, Radu I, Ryll H, Radu F, Zabel H. ALICE—An advanced reflectometer for static and dynamic experiments in magnetism at synchrotron radiation facilities. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:063902. [PMID: 26133845 DOI: 10.1063/1.4921716] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We report on significant developments of a high vacuum reflectometer (diffractometer) and spectrometer for soft x-ray synchrotron experiments which allows conducting a wide range of static and dynamic experiments. Although the chamber named ALICE was designed for the analysis of magnetic hetero- and nanostructures via resonant magnetic x-ray scattering, the instrument is not limited to this technique. The versatility of the instrument was testified by a series of pilot experiments. Static measurements involve the possibility to use scattering and spectroscopy synchrotron based techniques (photon-in photon-out, photon-in electron-out, and coherent scattering). Dynamic experiments require either laser or magnetic field pulses to excite the spin system followed by x-ray probe in the time domain from nano- to femtosecond delay times. In this temporal range, the demagnetization/remagnetization dynamics and magnetization precession in a number of magnetic materials (metals, alloys, and magnetic multilayers) can be probed in an element specific manner. We demonstrate here the capabilities of the system to host a variety of experiments, featuring ALICE as one of the most versatile and demanded instruments at the Helmholtz Center in Berlin-BESSY II synchrotron center in Berlin, Germany.
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Affiliation(s)
- R Abrudan
- Institute for Condensed Matter Physics, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - F Brüssing
- Institute for Condensed Matter Physics, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - R Salikhov
- Institute for Condensed Matter Physics, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - J Meermann
- Institute for Condensed Matter Physics, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - I Radu
- Helmholtz-Zentrum-Berlin for Materials and Energy, 12489 Berlin, Germany
| | - H Ryll
- Helmholtz-Zentrum-Berlin for Materials and Energy, 12489 Berlin, Germany
| | - F Radu
- Helmholtz-Zentrum-Berlin for Materials and Energy, 12489 Berlin, Germany
| | - H Zabel
- Institute for Condensed Matter Physics, Ruhr-Universität Bochum, 44780 Bochum, Germany
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28
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Huang X, Xu HG, Lu S, Su Y, King RB, Zhao J, Zheng W. Discovery of a silicon-based ferrimagnetic wheel structure in V(x)Si(12)(-) (x = 1-3) clusters: photoelectron spectroscopy and density functional theory investigation. NANOSCALE 2014; 6:14617-14621. [PMID: 25292334 DOI: 10.1039/c4nr03130j] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Our studies show that VSi(12)(-) adopts a V-centered hexagonal prism with a singlet spin state. The addition of the second V atom leads to a capped hexagonal antiprism for V(2)Si(12)(-) in a doublet spin state. Most interestingly, V(3)Si(12)(-) exhibits a ferrimagnetic, bicapped hexagonal antiprism wheel-like structure with a total spin of 4 μ(B).
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Affiliation(s)
- Xiaoming Huang
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, China.
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29
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Juhin A, López-Ortega A, Sikora M, Carvallo C, Estrader M, Estradé S, Peiró F, Baró MD, Sainctavit P, Glatzel P, Nogués J. Direct evidence for an interdiffused intermediate layer in bi-magnetic core-shell nanoparticles. NANOSCALE 2014; 6:11911-11920. [PMID: 25174899 DOI: 10.1039/c4nr02886d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Core-shell nanoparticles attract continuously growing interest due to their numerous applications, which are driven by the possibility of tuning their functionalities by adjusting structural and morphological parameters. However, despite the critical role interdiffused interfaces may have in the properties, these are usually only estimated in indirect ways. Here we directly evidence the existence of a 1.1 nm thick (Fe,Mn)3O4 interdiffused intermediate shell in nominally γ-Fe2O3-Mn3O4 core-shell nanoparticles using resonant inelastic X-ray scattering spectroscopy combined with magnetic circular dichroism (RIXS-MCD). This recently developed magneto-spectroscopic probe exploits the unique advantages of hard X-rays (i.e., chemical selectivity, bulk sensitivity, and low self-absorption at the K pre-edge) and can be advantageously combined with transmission electron microscopy and electron energy loss spectroscopy to quantitatively elucidate the buried internal structure of complex objects. The detailed information on the structure of the nanoparticles allows understanding the influence of the interface quality on the magnetic properties.
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Affiliation(s)
- Amélie Juhin
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités, UMR CNRS 7590, UPMC Univ Paris 06, Muséum National d'Histoire Naturelle, IRD UMR 206, 4 Place Jussieu, F-75005 Paris, France.
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30
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Exchange coupling driven omnidirectional rotatable anisotropy in ferrite doped CoFe thin film. Sci Rep 2012; 2:832. [PMID: 23145323 PMCID: PMC3494020 DOI: 10.1038/srep00832] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 09/27/2012] [Indexed: 11/26/2022] Open
Abstract
Isotropic magnetic materials with high resonant frequencies are useful for applications in microwave devices. Undoped CoFe thin films, as common soft magnetic materials with high saturation magnetization, show isotropic characteristics but no high frequency response. Here, we use ferrite doped CoFe thin film to realize a resonant frequency higher than 4.5 GHz at all orientations. The exchange coupling between ferrimagnet and ferromagnet is assumed to play a key role on the omnidirectional rotatable anisotropy.
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