51
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Zhang S, Burn DM, Jaouen N, Chauleau JY, Haghighirad AA, Liu Y, Wang W, van der Laan G, Hesjedal T. Robust Perpendicular Skyrmions and Their Surface Confinement. NANO LETTERS 2020; 20:1428-1432. [PMID: 31928021 PMCID: PMC7145360 DOI: 10.1021/acs.nanolett.9b05141] [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: 12/13/2019] [Revised: 01/05/2020] [Indexed: 06/10/2023]
Abstract
Magnetic skyrmions are two-dimensional magnetization swirls that stack in the form of tubes in the third dimension and which are proposed as prospective information carriers for nonvolatile memory devices due to their unique topological properties. From resonant elastic X-ray scattering measurements on Cu2OSeO3 with an in-plane magnetic field, we find that a state of perpendicularly ordered skyrmions forms, in stark contrast to the well-studied bulk state. The surface state is stable over a wide temperature range, unlike the bulk state in out-of-plane fields which is confined to a narrow region of the temperature-field phase diagram. In contrast to ordinary skyrmions found in the bulk, the surface state skyrmions result from the presence of magnetic interactions unique to the surface which stabilize them against external perturbations. The surface guiding makes the robust state particular interesting for racetracklike devices, ultimately allowing for much higher storage densities due to the smaller lateral footprint of the perpendicular skyrmions.
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Affiliation(s)
- Shilei Zhang
- School of
Physical Science and Technology and ShanghaiTech Laboratory for Topological
Physics, ShanghaiTech University, Shanghai 200031, China
- Department
of Physics, Clarendon Laboratory and Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United
Kingdom
| | - David M. Burn
- Magnetic
Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE, United Kingdom
| | - Nicolas Jaouen
- Synchrotron
SOLEIL, L’Orme
des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette, France
| | - Jean-Yves Chauleau
- Synchrotron
SOLEIL, L’Orme
des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette, France
| | - Amir A. Haghighirad
- Department
of Physics, Clarendon Laboratory and Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United
Kingdom
- Institute
for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - Yizhou Liu
- Beijing
National Laboratory for Condensed Matter Physics and Institute of
Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Weiwei Wang
- Institutes
of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Gerrit van der Laan
- Magnetic
Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE, United Kingdom
| | - Thorsten Hesjedal
- Department
of Physics, Clarendon Laboratory and Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United
Kingdom
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52
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Magnetic Materials and Systems: Domain Structure Visualization and Other Characterization Techniques for the Application in the Materials Science and Biomedicine. INORGANICS 2020. [DOI: 10.3390/inorganics8010006] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Magnetic structures have attracted a great interest due to their multiple applications, from physics to biomedicine. Several techniques are currently employed to investigate magnetic characteristics and other physicochemical properties of magnetic structures. The major objective of this review is to summarize the current knowledge on the usage, advances, advantages, and disadvantages of a large number of techniques that are currently available to characterize magnetic systems. The present review, aiming at helping in the choice of the most suitable method as appropriate, is divided into three sections dedicated to characterization techniques. Firstly, the magnetism and magnetization (hysteresis) techniques are introduced. Secondly, the visualization methods of the domain structures by means of different probes are illustrated. Lastly, the characterization of magnetic nanosystems in view of possible biomedical applications is discussed, including the exploitation of magnetism in imaging for cell tracking/visualization of pathological alterations in living systems (mainly by magnetic resonance imaging, MRI).
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53
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Burn DM, Zhang S, Zhai K, Chai Y, Sun Y, van der Laan G, Hesjedal T. Mode-Resolved Detection of Magnetization Dynamics Using X-ray Diffractive Ferromagnetic Resonance. NANO LETTERS 2020; 20:345-352. [PMID: 31855436 DOI: 10.1021/acs.nanolett.9b03989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Collective spin excitations of ordered magnetic structures offer great potential for the development of novel spintronic devices. The present approach relies on micromagnetic models to explain the origins of dynamic modes observed by ferromagnetic resonance (FMR) studies, since experimental tools to directly reveal the origins of the complex dynamic behavior are lacking. Here we demonstrate a new approach which combines resonant magnetic X-ray diffraction with FMR, thereby allowing for a reconstruction of the real-space spin dynamics of the system. This new diffractive FMR technique builds on X-ray detected FMR that allows for element-selective dynamic studies, giving unique access to specific wave components of static and dynamic coupling in magnetic heterostructures. In combination with diffraction, FMR is elevated to the level of a modal spectroscopy technique, potentially opening new pathways for the development of spintronic devices.
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Affiliation(s)
- David M Burn
- Magnetic Spectroscopy Group , Diamond Light Source , Didcot OX11 0DE , United Kingdom
| | - Shilei Zhang
- School of Physical Science and Technology , ShanghaiTech University , Shanghai , 201210 , China
- ShanghaiTech Laboratory for Topological Physics , ShanghaiTech University , Shanghai 200031 , China
| | - Kun Zhai
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
- School of Physical Science , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Yisheng Chai
- Low Temperature Physics Laboratory, College of Physics, and Center of Quantum Materials and Devices , Chongqing University , Chongqing 401331 , China
| | - Young Sun
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
- School of Physical Science , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Gerrit van der Laan
- Magnetic Spectroscopy Group , Diamond Light Source , Didcot OX11 0DE , United Kingdom
| | - Thorsten Hesjedal
- Clarendon Laboratory, Department of Physics , University of Oxford , Parks Road , Oxford OX1 3PU , United Kingdom
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54
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Ferreira M, Sousa J, Pais A, Vitorino C. The Role of Magnetic Nanoparticles in Cancer Nanotheranostics. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E266. [PMID: 31936128 PMCID: PMC7014348 DOI: 10.3390/ma13020266] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/05/2020] [Accepted: 01/06/2020] [Indexed: 02/07/2023]
Abstract
Technological development is in constant progress in the oncological field. The search for new concepts and strategies for improving cancer diagnosis, treatment and outcomes constitutes a necessary and continuous process, aiming at more specificity, efficiency, safety and better quality of life of the patients throughout the treatment. Nanotechnology embraces these purposes, offering a wide armamentarium of nanosized systems with the potential to incorporate both diagnosis and therapeutic features, towards real-time monitoring of cancer treatment. Within the nanotechnology field, magnetic nanosystems stand out as complex and promising nanoparticles with magnetic properties, that enable the use of these constructs for magnetic resonance imaging and thermal therapy purposes. Additionally, magnetic nanoparticles can be tailored for increased specificity and reduced toxicity, and functionalized with contrast, targeting and therapeutic agents, revealing great potential as multifunctional nanoplatforms for application in cancer theranostics. This review aims at providing a comprehensive description of the current designs, characterization techniques, synthesis methods, and the role of magnetic nanoparticles as promising nanotheranostic agents. A critical appraisal of the impact, potentialities and challenges associated with each technology is also presented.
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Affiliation(s)
- Maria Ferreira
- Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal; (M.F.); (J.S.)
| | - João Sousa
- Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal; (M.F.); (J.S.)
- Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal;
| | - Alberto Pais
- Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal;
| | - Carla Vitorino
- Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal; (M.F.); (J.S.)
- Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal;
- Centre for Neurosciences and Cell Biology (CNC), Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
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55
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Nakano M, Wang Y, Yoshida S, Matsuoka H, Majima Y, Ikeda K, Hirata Y, Takeda Y, Wadati H, Kohama Y, Ohigashi Y, Sakano M, Ishizaka K, Iwasa Y. Intrinsic 2D Ferromagnetism in V 5Se 8 Epitaxial Thin Films. NANO LETTERS 2019; 19:8806-8810. [PMID: 31714089 DOI: 10.1021/acs.nanolett.9b03614] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The discoveries of intrinsic ferromagnetism in atomically thin van der Waals crystals have opened a new research field enabling fundamental studies on magnetism at two-dimensional (2D) limit as well as development of magnetic van der Waals heterostructures. Currently, a variety of 2D ferromagnetism has been explored mainly by mechanically exfoliating "originally ferromagnetic (FM)" van der Waals crystals, while a bottom-up approach by thin-film growth technique has demonstrated emergent 2D ferromagnetism in a variety of "originally non-FM" van der Waals materials. Here we demonstrate that V5Se8 epitaxial thin films grown by molecular-beam epitaxy exhibit emergent 2D ferromagnetism with intrinsic spin polarization of the V 3d electrons despite that the bulk counterpart is "originally antiferromagnetic". Moreover, thickness-dependence measurements reveal that this newly developed 2D ferromagnet could be classified as an itinerant 2D Heisenberg ferromagnet with weak magnetic anisotropy, broadening a lineup of 2D magnets to those potentially beneficial for future spintronics applications.
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Affiliation(s)
- Masaki Nakano
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
- RIKEN Center for Emergent Matter Science , Wako 351-0198 , Japan
| | - Yue Wang
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Satoshi Yoshida
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Hideki Matsuoka
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Yuki Majima
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Keisuke Ikeda
- Department of Physics , the University of Tokyo , Tokyo 113-0033 , Japan
| | - Yasuyuki Hirata
- Department of Physics , the University of Tokyo , Tokyo 113-0033 , Japan
- The Institute for Solid State Physics , the University of Tokyo , Kashiwa 227-8581 , Japan
| | - Yukiharu Takeda
- Materials Sciences Research Center , Japan Atomic Energy Agency , Koto City 679-5148 , Hyogo , Japan
| | - Hiroki Wadati
- Department of Physics , the University of Tokyo , Tokyo 113-0033 , Japan
- The Institute for Solid State Physics , the University of Tokyo , Kashiwa 227-8581 , Japan
| | - Yoshimitsu Kohama
- The Institute for Solid State Physics , the University of Tokyo , Kashiwa 227-8581 , Japan
| | - Yuta Ohigashi
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Masato Sakano
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Kyoko Ishizaka
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
- RIKEN Center for Emergent Matter Science , Wako 351-0198 , Japan
| | - Yoshihiro Iwasa
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
- RIKEN Center for Emergent Matter Science , Wako 351-0198 , Japan
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56
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Kaneyasu T, Hikosaka Y, Fujimoto M, Iwayama H, Katoh M. Controlling the Orbital Alignment in Atoms Using Cross-Circularly Polarized Extreme Ultraviolet Wave Packets. PHYSICAL REVIEW LETTERS 2019; 123:233401. [PMID: 31868498 DOI: 10.1103/physrevlett.123.233401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/26/2019] [Indexed: 06/10/2023]
Abstract
We report on the use of pairs of 10-cycle extreme ultraviolet wave packets with attosecond-controlled spacing emitted by individual relativistic electrons within an electron bunch passing through a tandem undulator. Based on the temporal coherent control technique with circular polarization, we succeeded in controlling the excited state alignment in the photoexcitation of helium atoms, which we verified through the observation of oscillation in fluorescence yield depending on the attosecond-controlled delay time. Our work demonstrates the potential of undulator radiation for the generation of longitudinally coherent wave packets suitable for attosecond coherent control, an application which has hitherto been hidden in the incoherent nature of the radiation pulse emitted by a bunch of electrons.
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Affiliation(s)
- T Kaneyasu
- SAGA Light Source, Tosu 841-0005, Japan
- Institute for Molecular Science, Okazaki 444-8585, Japan
| | - Y Hikosaka
- Institute of Liberal Arts and Sciences, University of Toyama, Toyama 930-0194, Japan
| | - M Fujimoto
- Institute for Molecular Science, Okazaki 444-8585, Japan
- Sokendai (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan
| | - H Iwayama
- Institute for Molecular Science, Okazaki 444-8585, Japan
- Sokendai (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan
| | - M Katoh
- Institute for Molecular Science, Okazaki 444-8585, Japan
- Sokendai (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
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57
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Gao N, Je SG, Im MY, Choi JW, Yang M, Li Q, Wang TY, Lee S, Han HS, Lee KS, Chao W, Hwang C, Li J, Qiu ZQ. Creation and annihilation of topological meron pairs in in-plane magnetized films. Nat Commun 2019; 10:5603. [PMID: 31811144 PMCID: PMC6898613 DOI: 10.1038/s41467-019-13642-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 11/18/2019] [Indexed: 11/10/2022] Open
Abstract
Merons which are topologically equivalent to one-half of skyrmions can exist only in pairs or groups in two-dimensional (2D) ferromagnetic (FM) systems. The recent discovery of meron lattice in chiral magnet Co8Zn9Mn3 raises the immediate challenging question that whether a single meron pair, which is the most fundamental topological structure in any 2D meron systems, can be created and stabilized in a continuous FM film? Utilizing winding number conservation, we develop a new method to create and stabilize a single pair of merons in a continuous Py film by local vortex imprinting from a Co disk. By observing the created meron pair directly within a magnetic field, we determine its topological structure unambiguously and explore the topological effect in its creation and annihilation processes. Our work opens a pathway towards developing and controlling topological structures in general magnetic systems without the restriction of perpendicular anisotropy and Dzyaloshinskii–Moriya interaction. A meron is one half of a skyrmion but whether a single meron pair can be created and stabilized remains a challenging question. Here, Gao et al. develop a method to create and stabilize individual pairs of merons in a continuous Py film by local vortex imprinting from Co disks.
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Affiliation(s)
- N Gao
- Key Laboratory of Microelectronic Devices and Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing, 100029, China.,Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - S -G Je
- Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - M -Y Im
- Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Emerging Materials Science, DGIST, Daegu, Korea
| | - J W Choi
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - M Yang
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Q Li
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - T Y Wang
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - S Lee
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - H -S Han
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - K -S Lee
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - W Chao
- Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - C Hwang
- Korea Research Institute of Standards and Science, Yuseong, Daejeon, 305-340, Korea
| | - J Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China.
| | - Z Q Qiu
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA.
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58
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Studniarek M, Wäckerlin C, Singha A, Baltic R, Diller K, Donati F, Rusponi S, Brune H, Lan Y, Klyatskaya S, Ruben M, Seitsonen AP, Dreiser J. Understanding the Superior Stability of Single-Molecule Magnets on an Oxide Film. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1901736. [PMID: 31763154 PMCID: PMC6864999 DOI: 10.1002/advs.201901736] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/05/2019] [Indexed: 05/12/2023]
Abstract
The stability of magnetic information stored in surface adsorbed single-molecule magnets is of critical interest for applications in nanoscale data storage or quantum computing. The present study combines X-ray magnetic circular dichroism, density functional theory and magnetization dynamics calculations to gain deep insight into the substrate dependent relevant magnetization relaxation mechanisms. X-ray magnetic circular dichroism reveals the opening of a butterfly-shaped magnetic hysteresis of DyPc2 molecules on magnesium oxide and a closed loop on the bare silver substrate, while density functional theory shows that the molecules are only weakly adsorbed in both cases of magnesium oxide and silver. The enhanced magnetic stability of DyPc2 on the oxide film, in conjunction with previous experiments on the TbPc2 analogue, points to a general validity of the magnesium oxide induced stabilization effect. Magnetization dynamics calculations reveal that the enhanced magnetic stability of DyPc2 and TbPc2 on the oxide film is due to the suppression of two-phonon Raman relaxation processes. The results suggest that substrates with low phonon density of states are beneficial for the design of spintronics devices based on single-molecule magnets.
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Affiliation(s)
- Michał Studniarek
- Swiss Light SourcePaul Scherrer Institut (PSI)CH‐5232VilligenSwitzerland
| | - Christian Wäckerlin
- Institute of Physics (IPHYS)École Polytechnique Fédérale de Lausanne (EPFL)Station 3CH‐1015LausanneSwitzerland
- Institute of PhysicsThe Czech Academy of SciencesCukrovarnická 10CZ‐162 00Prague 6Czech Republic
| | - Aparajita Singha
- Institute of Physics (IPHYS)École Polytechnique Fédérale de Lausanne (EPFL)Station 3CH‐1015LausanneSwitzerland
- Center for Quantum NanoscienceInstitute for Basic Science (IBS)03760SeoulRepublic of Korea
- Department of PhysicsEwha Womans University03760SeoulRepublic of Korea
| | - Romana Baltic
- Institute of Physics (IPHYS)École Polytechnique Fédérale de Lausanne (EPFL)Station 3CH‐1015LausanneSwitzerland
| | - Katharina Diller
- Institute of Physics (IPHYS)École Polytechnique Fédérale de Lausanne (EPFL)Station 3CH‐1015LausanneSwitzerland
| | - Fabio Donati
- Institute of Physics (IPHYS)École Polytechnique Fédérale de Lausanne (EPFL)Station 3CH‐1015LausanneSwitzerland
- Center for Quantum NanoscienceInstitute for Basic Science (IBS)03760SeoulRepublic of Korea
- Department of PhysicsEwha Womans University03760SeoulRepublic of Korea
| | - Stefano Rusponi
- Institute of Physics (IPHYS)École Polytechnique Fédérale de Lausanne (EPFL)Station 3CH‐1015LausanneSwitzerland
| | - Harald Brune
- Institute of Physics (IPHYS)École Polytechnique Fédérale de Lausanne (EPFL)Station 3CH‐1015LausanneSwitzerland
| | - Yanhua Lan
- Institute of Nanotechnology (INT)Karlsruhe Institute of Technology (KIT)Hermann‐von‐Helmholtz‐Platz 1D‐76344Eggenstein‐LeopoldshafenGermany
| | - Svetlana Klyatskaya
- Institute of Nanotechnology (INT)Karlsruhe Institute of Technology (KIT)Hermann‐von‐Helmholtz‐Platz 1D‐76344Eggenstein‐LeopoldshafenGermany
| | - Mario Ruben
- Institute of Nanotechnology (INT)Karlsruhe Institute of Technology (KIT)Hermann‐von‐Helmholtz‐Platz 1D‐76344Eggenstein‐LeopoldshafenGermany
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS)Centre National de la Recherche Scientifique (CNRS)Université de Strasbourg23 rue du Loess, BP 43F‐67034Strasbourg Cedex 2France
| | - Ari Paavo Seitsonen
- Département de ChimieÉcole Normale SupérieureF‐75005ParisFrance
- Centre National de la Recherche Scientifique (CNRS)Paris Sciences et LettresSorbonne UniversitéF‐75005ParisFrance
| | - Jan Dreiser
- Swiss Light SourcePaul Scherrer Institut (PSI)CH‐5232VilligenSwitzerland
- Institute of Physics (IPHYS)École Polytechnique Fédérale de Lausanne (EPFL)Station 3CH‐1015LausanneSwitzerland
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59
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Pedersen KS, Meihaus KR, Rogalev A, Wilhelm F, Aravena D, Amoza M, Ruiz E, Long JR, Bendix J, Clérac R. [UF
6
]
2−
: A Molecular Hexafluorido Actinide(IV) Complex with Compensating Spin and Orbital Magnetic Moments. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201905056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Kasper S. Pedersen
- Univ. Bordeaux, CNRS Centre de Recherche Paul Pascal, UMR 5031 33600 Pessac France
- Department of Chemistry Technical University of Denmark, 2800 Kgs. Lyngby Denmark
| | - Katie R. Meihaus
- Department of Chemistry University of California Berkeley CA 94720 USA
| | - Andrei Rogalev
- ESRF–The European Synchrotron, 71, Avenue des Martyrs 38000 Grenoble Cedex 9 France
| | - Fabrice Wilhelm
- ESRF–The European Synchrotron, 71, Avenue des Martyrs 38000 Grenoble Cedex 9 France
| | - Daniel Aravena
- Departamento de Química de los Materiales Facultad de Química y Biología Universidad de Santiago de Chile (USACH) Casilla 40, Correo 33 Santiago Chile
| | - Martín Amoza
- Departament de Química Inorgànica i Orgànica and Institut de Química Teòrica i Computacional Universitat de Barcelona Diagonal 645 08028 Barcelona Spain
| | - Eliseo Ruiz
- Departament de Química Inorgànica i Orgànica and Institut de Química Teòrica i Computacional Universitat de Barcelona Diagonal 645 08028 Barcelona Spain
| | - Jeffrey R. Long
- Department of Chemistry University of California Berkeley CA 94720 USA
- Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
- Department of Chemical and Biomolecular Engineering University of California Berkeley Berkeley CA 94720 USA
| | - Jesper Bendix
- Department of Chemistry University of Copenhagen 2100 Copenhagen Denmark
| | - Rodolphe Clérac
- Univ. Bordeaux, CNRS Centre de Recherche Paul Pascal, UMR 5031 33600 Pessac France
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60
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Callefo F, Maldanis L, Teixeira VC, Abans RADO, Monfredini T, Rodrigues F, Galante D. Evaluating Biogenicity on the Geological Record With Synchrotron-Based Techniques. Front Microbiol 2019; 10:2358. [PMID: 31681221 PMCID: PMC6798071 DOI: 10.3389/fmicb.2019.02358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 09/27/2019] [Indexed: 11/17/2022] Open
Abstract
The biogenicity problem of geological materials is one of the most challenging ones in the field of paleo and astrobiology. As one goes deeper in time, the traces of life become feeble and ambiguous, blending with the surrounding geology. Well-preserved metasedimentary rocks from the Archaean are relatively rare, and in very few cases contain structures resembling biological traces or fossils. These putative biosignatures have been studied for decades and many biogenicity criteria have been developed, but there is still no consensus for many of the proposed structures. Synchrotron-based techniques, especially on new generation sources, have the potential for contributing to this field of research, providing high sensitivity and resolution that can be advantageous for different scientific problems. Exploring the X-ray and matter interactions on a range of geological materials can provide insights on morphology, elemental composition, oxidation states, crystalline structure, magnetic properties, and others, which can measurably contribute to the investigation of biogenicity of putative biosignatures. Here, we provide an overview of selected synchrotron-based techniques that have the potential to be applied in different types of questions on the study of biosignatures preserved in the geological record. The development of 3rd and recently 4th generation synchrotron sources will favor a deeper understanding of the earliest records of life on Earth and also bring up potential analytical approaches to be applied for the search of biosignatures in meteorites and samples returned from Mars in the near future.
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Affiliation(s)
- Flavia Callefo
- Brazilian Synchrotron Light Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, Brazil
| | - Lara Maldanis
- Brazilian Synchrotron Light Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, Brazil
- Institute of Physics of São Carlos, University of São Paulo, São Paulo, Brazil
| | - Verônica C. Teixeira
- Brazilian Synchrotron Light Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, Brazil
| | - Rodrigo Adrián de Oliveira Abans
- Brazilian Synchrotron Light Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, Brazil
- Interunits Graduate Program in Biotechnology, University of São Paulo, São Paulo, Brazil
| | - Thiago Monfredini
- Brazilian Synchrotron Light Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, Brazil
| | - Fabio Rodrigues
- Fundamental Chemistry Department, University of São Paulo, São Paulo, Brazil
| | - Douglas Galante
- Brazilian Synchrotron Light Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, Brazil
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61
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Pedersen KS, Meihaus KR, Rogalev A, Wilhelm F, Aravena D, Amoza M, Ruiz E, Long JR, Bendix J, Clérac R. [UF 6 ] 2- : A Molecular Hexafluorido Actinide(IV) Complex with Compensating Spin and Orbital Magnetic Moments. Angew Chem Int Ed Engl 2019; 58:15650-15654. [PMID: 31290580 DOI: 10.1002/anie.201905056] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/14/2019] [Indexed: 11/08/2022]
Abstract
The first structurally characterized hexafluorido complex of a tetravalent actinide ion, the [UF6 ]2- anion, is reported in the (NEt4 )2 [UF6 ]⋅2 H2 O salt (1). The weak magnetic response of 1 results from both UIV spin and orbital contributions, as established by combining X-ray magnetic circular dichroism (XMCD) spectroscopy and bulk magnetization measurements. The spin and orbital moments are virtually identical in magnitude, but opposite in sign, resulting in an almost perfect cancellation, which is corroborated by ab initio calculations. This work constitutes the first experimental demonstration of a seemingly non-magnetic molecular actinide complex carrying sizable spin and orbital magnetic moments.
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Affiliation(s)
- Kasper S Pedersen
- Univ. Bordeaux, CNRS, Centre de Recherche Paul Pascal, UMR 5031, 33600, Pessac, France.,Department of Chemistry, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| | - Katie R Meihaus
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - Andrei Rogalev
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, 38000, Grenoble Cedex 9, France
| | - Fabrice Wilhelm
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, 38000, Grenoble Cedex 9, France
| | - Daniel Aravena
- Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile (USACH), Casilla 40, Correo 33, Santiago, Chile
| | - Martín Amoza
- Departament de Química Inorgànica i Orgànica and Institut de Química Teòrica i Computacional, Universitat de Barcelona, Diagonal 645, 08028, Barcelona, Spain
| | - Eliseo Ruiz
- Departament de Química Inorgànica i Orgànica and Institut de Química Teòrica i Computacional, Universitat de Barcelona, Diagonal 645, 08028, Barcelona, Spain
| | - Jeffrey R Long
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Chemical and Biomolecular Engineering, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Jesper Bendix
- Department of Chemistry, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Rodolphe Clérac
- Univ. Bordeaux, CNRS, Centre de Recherche Paul Pascal, UMR 5031, 33600, Pessac, France
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62
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Burn DM, Duffy LB, Fujita R, Zhang SL, Figueroa AI, Herrero-Martin J, van der Laan G, Hesjedal T. Cr 2Te 3 Thin Films for Integration in Magnetic Topological Insulator Heterostructures. Sci Rep 2019; 9:10793. [PMID: 31346229 PMCID: PMC6658498 DOI: 10.1038/s41598-019-47265-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 07/12/2019] [Indexed: 11/09/2022] Open
Abstract
Chromium telluride compounds are promising ferromagnets for proximity coupling to magnetic topological insulators (MTIs) of the Cr-doped (Bi,Sb)2(Se,Te)3 class of materials as they share the same elements, thus simplifying thin film growth, as well as due to their compatible crystal structure. Recently, it has been demonstrated that high quality (001)-oriented Cr2Te3 thin films with perpendicular magnetic anisotropy can be grown on c-plane sapphire substrate. Here, we present a magnetic and soft x-ray absorption spectroscopy study of the chemical and magnetic properties of Cr2Te3 thin films. X-ray magnetic circular dichroism (XMCD) measured at the Cr L2,3 edges gives information about the local electronic and magnetic structure of the Cr ions. We further demonstrate the overgrowth of Cr2Te3 (001) thin films by high-quality Cr-doped Sb2Te3 films. The magnetic properties of the layers have been characterized and our results provide a starting point for refining the physical models of the complex magnetic ordering in Cr2Te3 thin films, and their integration into advanced MTI heterostructures for quantum device applications.
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Affiliation(s)
- D M Burn
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot, OX11 0DE, United Kingdom
| | - L B Duffy
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom.,ISIS, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Oxon, OX11 0QX, United Kingdom
| | - R Fujita
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot, OX11 0DE, United Kingdom.,Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
| | - S L Zhang
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
| | - A I Figueroa
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot, OX11 0DE, United Kingdom.,Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, Campus UAB, Barcelona, 08193, Spain
| | - J Herrero-Martin
- CELLS-Divisió Experiments, ALBA Synchrotron Light Source, E-08290 Cerdanyola del Vallès, Barcelona, Catalonia, Spain
| | - G van der Laan
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot, OX11 0DE, United Kingdom
| | - T Hesjedal
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom.
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63
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Vectorizing the spatial structure of high-harmonic radiation from gas. Nat Commun 2019; 10:2020. [PMID: 31043591 PMCID: PMC6494894 DOI: 10.1038/s41467-019-10014-5] [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: 12/20/2018] [Accepted: 04/01/2019] [Indexed: 11/25/2022] Open
Abstract
Strong field laser physics has primarily been concerned with controlling beams in time while keeping their spatial profiles invariant. In the case of high harmonic generation, the harmonic beam is the result of the coherent superposition of atomic dipole emissions. Therefore, fundamental beams can be tailored in space, and their spatial characteristics will be imparted onto the harmonics. Here we produce high harmonics using a space-varying polarized fundamental laser beam, which we refer to as a vector beam. By exploiting the natural evolution of a vector beam as it propagates, we convert the fundamental beam into high harmonic radiation at its focus where the polarization is primarily linear. This evolution results in circularly polarized high harmonics in the far field. Such beams will be important for ultrafast probing of magnetic materials. Ultrafast pulses with controlled parameters are desirable in many applications including probing materials and their interaction with light. Here the authors demonstrate a technique for polarization control of XUV beam using high-harmonic generation and polarization shaping.
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64
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Song D, Wang Z, Zhu J. Magnetic measurement by electron magnetic circular dichroism in the transmission electron microscope. Ultramicroscopy 2019; 201:1-17. [PMID: 30904784 DOI: 10.1016/j.ultramic.2019.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 03/05/2019] [Accepted: 03/18/2019] [Indexed: 10/27/2022]
Abstract
Magnetic measurement by transmitted electrons at nanometer or even atomic scale is always an attractive and challenging issue in the transmission electron microscope. Electron magnetic circular dichroism, proposed in 2003 and realized in 2006, opens a new insight into the measurement of local magnetic properties. Later, it is developed into a powerful technique for quantitative magnetic measurement with site specificity and element specificity at high spatial resolution over years of efforts, both in the aspect of theory and experiments. The novel technique has been widely applied to the characterization of magnetic materials now. This present review gives an overview of its development and applications in the past fifteen years since its invention. The theory of electron magnetic circular dichroism and its development are reviewed. The diffraction geometry and experimental setups are summarized. The general way for quantitative measurement of magnetic parameters is presented with typical cases. Representative breakthroughs in method development and applications over a wide range of materials are then described. Finally, prospects for future development are briefly discussed.
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Affiliation(s)
- Dongsheng Song
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
| | - Ziqiang Wang
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Jing Zhu
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
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65
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Ramanantoanina H, Studniarek M, Daffé N, Dreiser J. Non-empirical calculation of X-ray magnetic circular dichroism in lanthanide compounds. Chem Commun (Camb) 2019; 55:2988-2991. [PMID: 30785135 DOI: 10.1039/c8cc09321k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Affordable calculations of X-ray magnetic circular dichroism and X-ray linear dichroism spectra of lanthanide ions purely based on structural input are difficult to achieve. Here we report on the successful application of ligand-field density-functional theory to obtain an exquisite reproduction of experimental spectra. As a testbed we use TbPc2 single-molecule magnets on a flat substrate.
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66
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Patra N, Sachan UGPS, SundarRajan S, Malhotra S, Harad V, Agarwal A, Divedi A, Jha SN, Bhattacharyya D. First results from the XMCD facility at the Energy-Dispersive EXAFS beamline of the Indus-2 synchrotron source. JOURNAL OF SYNCHROTRON RADIATION 2019; 26:445-449. [PMID: 30855254 DOI: 10.1107/s1600577519000602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 01/11/2019] [Indexed: 06/09/2023]
Abstract
Setting up of the X-ray Magnetic Circular Dichroism (XMCD) measurement facility with hard X-rays at the Energy-Dispersive EXAFS beamline (BL-08) at the Indus-2 synchrotron source is reported. This includes the design and development of a water-cooled electromagnet having a highest magnetic field of 2 T in a good field volume of 125 mm3 and having a 10 mm hole throughout for passage of the synchrotron beam. This also includes the development of an (X-Z-θ) motion stage for the heavy electromagnet for aligning its axis and the beam hole along the synchrotron beam direction. Along with the above developments, also reported is the first XMCD signal measured on a thick Gd film in the above set-up which shows good agreement with the reported results. This is the first facility to carry out XMCD measurement with hard X-rays in India.
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Affiliation(s)
- N Patra
- Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - U G P S Sachan
- Accelerator Control Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - S SundarRajan
- Accelerator Control Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Sanjay Malhotra
- Accelerator Control Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Vijay Harad
- Accelerator Control Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Ankur Agarwal
- Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Ashutosh Divedi
- Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - S N Jha
- Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - D Bhattacharyya
- Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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67
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Liu W, Xu Y, He L, van der Laan G, Zhang R, Wang K. Experimental observation of dual magnetic states in topological insulators. SCIENCE ADVANCES 2019; 5:eaav2088. [PMID: 30783626 PMCID: PMC6368422 DOI: 10.1126/sciadv.aav2088] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Accepted: 12/19/2018] [Indexed: 06/09/2023]
Abstract
The recently discovered topological phase offers new possibilities for spintronics and condensed matter. Even insulating material exhibits conductivity at the edges of certain systems, giving rise to an anomalous quantum Hall effect and other coherent spin transport phenomena, in which heat dissipation is minimized, with potential uses for next-generation energy-efficient electronics. While the metallic surface states of topological insulators (TIs) have been extensively studied, direct comparison of the surface and bulk magnetic properties of TIs has been little explored. We report unambiguous evidence for distinctly enhanced surface magnetism in a prototype magnetic TI, Cr-doped Bi2Se3. Using synchrotron-based x-ray techniques, we demonstrate a "three-step transition" model, with a temperature window of ~15 K, where the TI surface is magnetically ordered while the bulk is not. Understanding the dual magnetization process has strong implications for defining a physical model of magnetic TIs and lays the foundation for applications to information technology.
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Affiliation(s)
- Wenqing Liu
- York-Nanjing Joint Center (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University, Nanjing 210093, China
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Yongbing Xu
- York-Nanjing Joint Center (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University, Nanjing 210093, China
- Department of Electronic Engineering, The University of York, York YO10 5DD, UK
| | - Liang He
- York-Nanjing Joint Center (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University, Nanjing 210093, China
- Department of Electrical and Computer Engineering, Department of Materials Science and Engineering, and Department of Physics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | | | - Rong Zhang
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Kang Wang
- Department of Electrical and Computer Engineering, Department of Materials Science and Engineering, and Department of Physics, University of California, Los Angeles, Los Angeles, CA 90095, USA
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68
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Kappler JP, Otero E, Li W, Joly L, Schmerber G, Muller B, Scheurer F, Leduc F, Gobaut B, Poggini L, Serrano G, Choueikani F, Lhotel E, Cornia A, Sessoli R, Mannini M, Arrio MA, Sainctavit P, Ohresser P. Ultralow-temperature device dedicated to soft X-ray magnetic circular dichroism experiments. JOURNAL OF SYNCHROTRON RADIATION 2018; 25:1727-1735. [PMID: 30407183 PMCID: PMC6225739 DOI: 10.1107/s1600577518012717] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 09/07/2018] [Indexed: 06/08/2023]
Abstract
A new ultralow-temperature setup dedicated to soft X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) experiments is described. Two experiments, performed on the DEIMOS beamline (SOLEIL synchrotron), demonstrate the outstanding performance of this new platform in terms of the lowest achievable temperature under X-ray irradiation (T = 220 mK), the precision in controlling the temperature during measurements as well as the speed of the cooling-down and warming-up procedures. Moreover, owing to the new design of the setup, the eddy-current power is strongly reduced, allowing fast scanning of the magnetic field in XMCD experiments; these performances lead to a powerful device for X-ray spectroscopies on synchrotron-radiation beamlines facilities.
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Affiliation(s)
- J.-P. Kappler
- Synchrotron SOLEIL, L’Orme des Merisiers, BP 48, 91192 Gif-sur-Yvette, France
| | - E. Otero
- Synchrotron SOLEIL, L’Orme des Merisiers, BP 48, 91192 Gif-sur-Yvette, France
| | - W. Li
- Synchrotron SOLEIL, L’Orme des Merisiers, BP 48, 91192 Gif-sur-Yvette, France
| | - L. Joly
- Synchrotron SOLEIL, L’Orme des Merisiers, BP 48, 91192 Gif-sur-Yvette, France
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 23 rue du Loess, 67034 Strasbourg, France
| | - G. Schmerber
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 23 rue du Loess, 67034 Strasbourg, France
| | - B. Muller
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 23 rue du Loess, 67034 Strasbourg, France
| | - F. Scheurer
- Synchrotron SOLEIL, L’Orme des Merisiers, BP 48, 91192 Gif-sur-Yvette, France
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 23 rue du Loess, 67034 Strasbourg, France
| | - F. Leduc
- Synchrotron SOLEIL, L’Orme des Merisiers, BP 48, 91192 Gif-sur-Yvette, France
| | - B. Gobaut
- Synchrotron SOLEIL, L’Orme des Merisiers, BP 48, 91192 Gif-sur-Yvette, France
| | - L. Poggini
- Department of Chemistry ‘U. Schiff’ and INSTM RU, University of Firenze, Via della Lastruccia n. 3, 50019 Sesto Fiorentino (FI), Italy
| | - G. Serrano
- Department of Chemistry ‘U. Schiff’ and INSTM RU, University of Firenze, Via della Lastruccia n. 3, 50019 Sesto Fiorentino (FI), Italy
| | - F. Choueikani
- Synchrotron SOLEIL, L’Orme des Merisiers, BP 48, 91192 Gif-sur-Yvette, France
| | - E. Lhotel
- Institut Néel, 25 rue des Martyrs, 38042 Grenoble, France
| | - A. Cornia
- Department of Chemical and Geological Sciences and INSTM RU, University of Modena and Reggio Emilia, via G. Campi 103, I-41125 Modena, Italy
| | - R. Sessoli
- Department of Chemistry ‘U. Schiff’ and INSTM RU, University of Firenze, Via della Lastruccia n. 3, 50019 Sesto Fiorentino (FI), Italy
| | - M. Mannini
- Department of Chemistry ‘U. Schiff’ and INSTM RU, University of Firenze, Via della Lastruccia n. 3, 50019 Sesto Fiorentino (FI), Italy
| | - M.-A. Arrio
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, IRD, MNHN, UMR 7590, 4 place Jussieu, 75252 Paris Cedex 05, France
| | - Ph. Sainctavit
- Synchrotron SOLEIL, L’Orme des Merisiers, BP 48, 91192 Gif-sur-Yvette, France
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, IRD, MNHN, UMR 7590, 4 place Jussieu, 75252 Paris Cedex 05, France
| | - P. Ohresser
- Synchrotron SOLEIL, L’Orme des Merisiers, BP 48, 91192 Gif-sur-Yvette, France
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Jedrecy N, Aghavnian T, Moussy JB, Magnan H, Stanescu D, Portier X, Arrio MA, Mocuta C, Vlad A, Belkhou R, Ohresser P, Barbier A. Cross-Correlation between Strain, Ferroelectricity, and Ferromagnetism in Epitaxial Multiferroic CoFe 2O 4/BaTiO 3 Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2018; 10:28003-28014. [PMID: 30085643 DOI: 10.1021/acsami.8b09499] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Multiferroic biphase systems with robust ferromagnetic and ferroelectric response at room temperature would be ideally suitable for voltage-controlled nonvolatile memories. Understanding the role of strain and charges at interfaces is central for an accurate control of the ferroelectricity as well as of the ferromagnetism. In this paper, we probe the relationship between the strain and the ferromagnetic/ferroelectric properties in the layered CoFe2O4/BaTiO3 (CFO/BTO) model system. For this purpose, ultrathin epitaxial bilayers, ranging from highly strained to fully relaxed, were grown by molecular beam epitaxy on Nb:SrTiO3(001). The lattice characteristics, determined by X-ray diffraction, evidence a non-intuitive cross-correlation: the strain in the bottom BTO layer depends on the thickness of the top CFO layer and vice versa. Plastic deformation participates in the relaxation process through dislocations at both interfaces, revealed by electron microscopy. Importantly, the switching of the BTO ferroelectric polarization, probed by piezoresponse force microscopy, is found dependent on the CFO thickness: the larger is the latter, the easiest is the BTO switching. In the thinnest thickness regime, the tetragonality of BTO and CFO has a strong impact on the 3d electronic levels of the different cations, which were probed by X-ray linear dichroism. The quantitative determination of the nature and repartition of the magnetic ions in CFO, as well as of their magnetic moments, has been carried out by X-ray magnetic circular dichroism, with the support of multiplet calculations. While bulklike ferrimagnetism is found for 5-15 nm thick CFO layers with a magnetization resulting as expected from the Co2+ ions alone, important changes occur at the interface with BTO over a thickness of 2-3 nm because of the formation of Fe2+ and Co3+ ions. This oxidoreduction process at the interface has strong implications concerning the mechanisms of polarity compensation and coupling in multiferroic heterostructures.
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Affiliation(s)
- Nathalie Jedrecy
- Institut des Nano Sciences de Paris (INSP) , Sorbonne Université, CNRS UMR 7588 , 4 Place Jussieu , 75252 Paris Cedex 05 , France
| | - Thomas Aghavnian
- Service de Physique de l'Etat Condensé (SPEC), CEA, CNRS UMR 3680, Université Paris Saclay, Orme des Merisiers, CEA Saclay , 91191 Gif sur Yvette Cedex , France
| | - Jean-Baptiste Moussy
- Service de Physique de l'Etat Condensé (SPEC), CEA, CNRS UMR 3680, Université Paris Saclay, Orme des Merisiers, CEA Saclay , 91191 Gif sur Yvette Cedex , France
| | - Hélène Magnan
- Service de Physique de l'Etat Condensé (SPEC), CEA, CNRS UMR 3680, Université Paris Saclay, Orme des Merisiers, CEA Saclay , 91191 Gif sur Yvette Cedex , France
| | - Dana Stanescu
- Service de Physique de l'Etat Condensé (SPEC), CEA, CNRS UMR 3680, Université Paris Saclay, Orme des Merisiers, CEA Saclay , 91191 Gif sur Yvette Cedex , France
| | - Xavier Portier
- Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP), CEA, CNRS UMR 6252, ENSICAEN, Normandie Université , 6 Boulevard Maréchal Juin , 14050 Caen , France
| | - Marie-Anne Arrio
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Université, CNRS UMR 7590, IRD, MNHN , 4 Place Jussieu , 75252 Paris Cedex 05 , France
| | - Cristian Mocuta
- Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin , BP 48, 91192 Gif sur Yvette Cedex , France
| | - Alina Vlad
- Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin , BP 48, 91192 Gif sur Yvette Cedex , France
| | - Rachid Belkhou
- Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin , BP 48, 91192 Gif sur Yvette Cedex , France
| | - Philippe Ohresser
- Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin , BP 48, 91192 Gif sur Yvette Cedex , France
| | - Antoine Barbier
- Service de Physique de l'Etat Condensé (SPEC), CEA, CNRS UMR 3680, Université Paris Saclay, Orme des Merisiers, CEA Saclay , 91191 Gif sur Yvette Cedex , France
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Bar AK, Kalita P, Singh MK, Rajaraman G, Chandrasekhar V. Low-coordinate mononuclear lanthanide complexes as molecular nanomagnets. Coord Chem Rev 2018. [DOI: 10.1016/j.ccr.2018.03.022] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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71
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Jafri SF, Arrio MA, Bordage A, Moulin R, Juhin A, Cartier dit Moulin C, Otero E, Ohresser P, Bleuzen A, Sainctavit P. Weak Ferromagnetic Interaction at the Surface of the Ferrimagnetic Rb2Co4[Fe(CN)6]3.3·11H2O Photoexcited State. Inorg Chem 2018; 57:7610-7619. [DOI: 10.1021/acs.inorgchem.8b00508] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sadaf Fatima Jafri
- CNRS, Sorbonne Université, IRD, MNHN, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR7590, 75252 Paris cedex 05, France
| | - Marie-Anne Arrio
- CNRS, Sorbonne Université, IRD, MNHN, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR7590, 75252 Paris cedex 05, France
| | - Amélie Bordage
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, Université Paris-Sud, CNRS, Université Paris-Saclay, 91405 Orsay cedex, France
| | - Robinson Moulin
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, Université Paris-Sud, CNRS, Université Paris-Saclay, 91405 Orsay cedex, France
| | - Amélie Juhin
- CNRS, Sorbonne Université, IRD, MNHN, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR7590, 75252 Paris cedex 05, France
| | | | - Edwige Otero
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, France
| | | | - Anne Bleuzen
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, Université Paris-Sud, CNRS, Université Paris-Saclay, 91405 Orsay cedex, France
| | - Philippe Sainctavit
- CNRS, Sorbonne Université, IRD, MNHN, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR7590, 75252 Paris cedex 05, France
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, France
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72
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Zhang SL, van der Laan G, Wang WW, Haghighirad AA, Hesjedal T. Direct Observation of Twisted Surface skyrmions in Bulk Crystals. PHYSICAL REVIEW LETTERS 2018; 120:227202. [PMID: 29906149 DOI: 10.1103/physrevlett.120.227202] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 03/22/2018] [Indexed: 06/08/2023]
Abstract
Magnetic skyrmions in noncentrosymmetric helimagnets with D_{n} symmetry are Bloch-type magnetization swirls with a helicity angle of ±90°. At the surface of helimagnetic thin films below a critical thickness, a twisted skyrmion state with an arbitrary helicity angle has been proposed; however, its direct experimental observation has remained elusive. Here, we show that circularly polarized resonant elastic x-ray scattering is able to unambiguously measure the helicity angle of surface skyrmions, providing direct experimental evidence that a twisted skyrmion surface state also exists in bulk systems. The exact surface helicity angles of twisted skyrmions for both left- and right-handed chiral bulk Cu_{2}OSeO_{3}, in the single as well as in the multidomain skyrmion lattice state, are determined, revealing their detailed internal structure. Our findings suggest that a skyrmion surface reconstruction is a universal phenomenon, stemming from the breaking of translational symmetry at the interface.
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Affiliation(s)
- S L Zhang
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - G van der Laan
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE, United Kingdom
| | - W W Wang
- Faculty of Science, Ningbo University, Ningbo 315211, China
| | - A A Haghighirad
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
- Institute for Solid State Physics, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - T Hesjedal
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
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73
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Collins SP, Lovesey SW. A unified formulation of dichroic signals using the Borrmann effect and twisted photon beams. Sci Rep 2018; 8:7941. [PMID: 29784947 PMCID: PMC5962556 DOI: 10.1038/s41598-018-23627-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 03/16/2018] [Indexed: 11/09/2022] Open
Abstract
Dichroic X-ray signals derived from the Borrmann effect and a twisted photon beam with topological charge l = 1 are formulated with an effective wavevector. The unification applies for non-magnetic and magnetic materials. Electronic degrees of freedom associated with an ion are encapsulated in multipoles previously used to interpret conventional dichroism and Bragg diffraction enhanced by an atomic resonance. A dichroic signal exploiting the Borrmann effect with a linearly polarized beam presents charge-like multipoles that include a hexadecapole. A difference between dichroic signals obtained with a twisted beam carrying spin polarization (circular polarization) and opposite winding numbers presents charge-like atomic multipoles, whereas a twisted beam carrying linear polarization alone presents magnetic (time-odd) multipoles. Charge-like multipoles include a quadrupole, and magnetic multipoles include a dipole and an octupole. We discuss the practicalities and relative merits of spectroscopy exploiting the two remarkably closely-related processes. Signals using beams with topological charges l ≥ 2 present additional atomic multipoles.
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Affiliation(s)
| | - Stephen W Lovesey
- Diamond Light Source Ltd, Oxfordshire, OX11 0DE, UK
- ISIS Facility, STFC, Oxfordshire, OX11 0QX, UK
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74
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Miedema PS, Beye M. Total 3s Emission Yield as Bulk-Sensitive Probe for a True Soft X-ray Absorption Spectrum? J Phys Chem Lett 2018; 9:2579-2583. [PMID: 29715037 DOI: 10.1021/acs.jpclett.8b00720] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The detection of the true soft X-ray absorption typically needs specially prepared submicrometer thin samples for transmission measurements. Bulk experiments instead have to rely on yield methods, for example, electron yield with limitations for insulating samples, sensitivity to applied fields, and with limited bulk sensitivity. Fluorescence yield methods instead do not have those limitations but have been found to deviate, in general, from the absorption spectrum. We demonstrate that restricting the detection to the 3s fluorescence channel (with the detector at a special angle where all polarizations contribute equally) restores the true X-ray absorption spectrum for all 3d-metal L2,3 edges. These theoretically derived results are rationalized by the lack of 3s-3d interaction in the core-excited state. Comparing X-ray absorption versus 3s-PFY for arbitrary detection geometries for both linear and circular polarized light, deviations appear that can become as large as 15%.
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Affiliation(s)
- Piter S Miedema
- DESY Photon Science, FS-FLASH , Notkestraße 85 , 22607 Hamburg , Germany
| | - Martin Beye
- DESY Photon Science, FS-FLASH , Notkestraße 85 , 22607 Hamburg , Germany
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75
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Huang Z, Zhang Y, He Y, Song H, Yin C, Wu K. A chemist's overview of surface electron spins. Chem Soc Rev 2018; 46:1955-1976. [PMID: 28317957 DOI: 10.1039/c6cs00891g] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This review summarizes recent research progress in the measurement and tuning of the electron spins of alien atoms and molecules adsorbed on well-defined substrates. After a brief introduction to the main experimental techniques employed to study surface electron spins, some well-explored systems consisting of atomic and molecular spin-carriers at surfaces are overviewed from a chemist's viewpoint, focusing on the experimental measurements and chemical modifications of the electron spin states of the alien entities at the surfaces on the atomic/molecular level. Finally, personal perspectives have been provided, aiming at describing some of the remaining issues that need to be addressed in the future and proposing potential applications in surface chemistry.
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Affiliation(s)
- Zhichao Huang
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Yajie Zhang
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Yang He
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Huanjun Song
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Cen Yin
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Kai Wu
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
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76
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Mössbauer spectroscopy of a monolayer of single molecule magnets. Nat Commun 2018; 9:480. [PMID: 29396458 PMCID: PMC5797240 DOI: 10.1038/s41467-018-02840-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 01/03/2018] [Indexed: 11/30/2022] Open
Abstract
The use of single molecule magnets (SMMs) as cornerstone elements in spintronics and quantum computing applications demands that magnetic bistability is retained when molecules are interfaced with solid conducting surfaces. Here, we employ synchrotron Mössbauer spectroscopy to investigate a monolayer of a tetrairon(III) (Fe4) SMM chemically grafted on a gold substrate. At low temperature and zero magnetic field, we observe the magnetic pattern of the Fe4 molecule, indicating slow spin fluctuations compared to the Mössbauer timescale. Significant structural deformations of the magnetic core, induced by the interaction with the substrate, as predicted by ab initio molecular dynamics, are also observed. However, the effects of the modifications occurring at the individual iron sites partially compensate each other, so that slow magnetic relaxation is retained on the surface. Interestingly, these deformations escaped detection by conventional synchrotron-based techniques, like X-ray magnetic circular dichroism, thus highlighting the power of synchrotron Mössbauer spectroscopy for the investigation of hybrid interfaces. Deposition of single molecule magnets onto surfaces is a key step for integration in devices exploiting their magnetic bistability and quantum properties. Here, Sessoli and colleagues exploit synchrotron Mössbauer spectroscopy to assess the effects of molecule-surface interactions on the magnetic properties of Fe(III) SMMs.
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77
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Moreno Pineda E, Komeda T, Katoh K, Yamashita M, Ruben M. Surface confinement of TbPc 2-SMMs: structural, electronic and magnetic properties. Dalton Trans 2018; 45:18417-18433. [PMID: 27824366 DOI: 10.1039/c6dt03298b] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Since 2003, terbium(iii) bis-phthalocyaninato complexes have been recognised as acting as single molecule magnets (SMMs), propitiating multiple studies with the aim of better understanding the single metal-ion based magnetism with unusually high blocking temperatures. In the quest for novel applications, it became clear that if spintronic devices were made from SMM molecules, their confinement in the proximity of surfaces or electrodes would become difficult to circumvent. In this perspective article, we highlight the influence of the presence of different substrates on the magnetic performance of TbPc2-SMMs, in principle caused by, among other effects, electronic hybridization, dipole-dipole coupling and changing quantum tunnelling (QT) rates on the surface. We show that the improved comprehension of how SMMs interact and communicate with the environment finally leads to magnetic remanence and lower tunnelling rates, paving the way to novel classes of spintronic devices.
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Affiliation(s)
- Eufemio Moreno Pineda
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.
| | - Tadahiro Komeda
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM, Tagen), Tohoku University, Japan
| | - Keiichi Katoh
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-Ku, Sendai 980-8578, Japan.
| | - Masahiro Yamashita
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-Ku, Sendai 980-8578, Japan. and WPI Research Center, Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Mario Ruben
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany. and WPI Research Center, Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan and Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS-Université de Strasbourg, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
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78
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Sassi M, Pearce CI, Bagus PS, Arenholz E, Rosso KM. First-Principles Fe L 2,3-Edge and O K-Edge XANES and XMCD Spectra for Iron Oxides. J Phys Chem A 2017; 121:7613-7618. [PMID: 28933158 DOI: 10.1021/acs.jpca.7b08392] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
X-ray absorption near-edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) spectroscopies are tools in widespread use for providing detailed local atomic structure, oxidation state, and magnetic structure information for materials and organometallic complexes. The analysis of these spectra for transition-metal L-edges is routinely performed on the basis of ligand-field multiplet theory because one- and two-particle mean-field ab initio methods typically cannot describe the multiplet structure. Here we show that multireference configuration interaction (MRCI) calculations can satisfactorily reproduce measured XANES spectra for a range of complex iron oxide materials including hematite and magnetite. MRCI Fe L2,3-edge XANES and XMCD spectra of Fe(II)O6, Fe(III)O6, and Fe(III)O4 in magnetite are found to be in very good qualitative agreement with experiment and multiplet calculations. Point-charge embedding and small distortions of the first-shell oxygen ligands have only small effects. Oxygen K-edge XANES/XMCD spectra for magnetite investigated by a real-space Green's function approach complete the very good qualitative agreement with experiment. Material-specific differences in local coordination and site symmetry are well reproduced, making the approach useful for assigning spectral features to specific oxidation states and coordination environments.
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Affiliation(s)
- Michel Sassi
- Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Carolyn I Pearce
- Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Paul S Bagus
- Department of Chemistry, University of North Texas , Denton, Texas 76203, United States
| | - Elke Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Kevin M Rosso
- Pacific Northwest National Laboratory , Richland, Washington 99352, United States
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79
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Iron Biochemistry is Correlated with Amyloid Plaque Morphology in an Established Mouse Model of Alzheimer's Disease. Cell Chem Biol 2017; 24:1205-1215.e3. [PMID: 28890316 DOI: 10.1016/j.chembiol.2017.07.014] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 01/19/2017] [Accepted: 07/28/2017] [Indexed: 11/21/2022]
Abstract
A signature characteristic of Alzheimer's disease (AD) is aggregation of amyloid-beta (Aβ) fibrils in the brain. Nevertheless, the links between Aβ and AD pathology remain incompletely understood. It has been proposed that neurotoxicity arising from aggregation of the Aβ1-42 peptide can in part be explained by metal ion binding interactions. Using advanced X-ray microscopy techniques at sub-micron resolution, we investigated relationships between iron biochemistry and AD pathology in intact cortex from an established mouse model over-producing Aβ. We found a direct correlation of amyloid plaque morphology with iron, and evidence for the formation of an iron-amyloid complex. We also show that iron biomineral deposits in the cortical tissue contain the mineral magnetite, and provide evidence that Aβ-induced chemical reduction of iron could occur in vivo. Our observations point to the specific role of iron in amyloid deposition and AD pathology, and may impact development of iron-modifying therapeutics for AD.
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80
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Zhang Y, Rouxel JR, Autschbach J, Govind N, Mukamel S. X-ray circular dichroism signals: a unique probe of local molecular chirality. Chem Sci 2017; 8:5969-5978. [PMID: 28989627 PMCID: PMC5620991 DOI: 10.1039/c7sc01347g] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 06/23/2017] [Indexed: 11/21/2022] Open
Abstract
Core-resonant circular dichroism (CD) signals are induced by molecular chirality and vanish for achiral molecules and racemic mixtures. The highly localized nature of core excitations makes them ideal probes of local chirality within molecules. Simulations of the circular dichroism spectra of several molecular families illustrate how these signals vary with the electronic coupling to substitution groups, the distance between the X-ray chromophore and the chiral center, geometry, and chemical structure. Clear insight into the molecular structure is obtained through analysis of the X-ray CD spectra.
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Affiliation(s)
- Yu Zhang
- Department of Chemistry , University of California , Irvine , CA 92697 , USA . ; ;
| | - Jérémy R Rouxel
- Department of Chemistry , University of California , Irvine , CA 92697 , USA . ; ;
| | - Jochen Autschbach
- Department of Chemistry , University at Buffalo , State University of New York , Buffalo , NY 14260 , USA .
| | - Niranjan Govind
- Environmental Molecular Sciences Laboratory , Pacific Northwest National Laboratory , Richland , WA 99352 , USA .
| | - Shaul Mukamel
- Department of Chemistry , University of California , Irvine , CA 92697 , USA . ; ;
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81
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Rouxel JR, Kowalewski M, Mukamel S. Photoinduced molecular chirality probed by ultrafast resonant X-ray spectroscopy. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2017; 4:044006. [PMID: 28191484 PMCID: PMC5291793 DOI: 10.1063/1.4974260] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 12/26/2016] [Indexed: 05/09/2023]
Abstract
Recently developed circularly polarized X-ray light sources can probe the ultrafast chiral electronic and nuclear dynamics through spatially localized resonant core transitions. We present simulations of time-resolved circular dichroism signals given by the difference of left and right circularly polarized X-ray probe transmission following an excitation by a circularly polarized optical pump with the variable time delay. Application is made to formamide which is achiral in the ground state and assumes two chiral geometries upon optical excitation to the first valence excited state. Probes resonant with various K-edges (C, N, and O) provide different local windows onto the parity breaking geometry change thus revealing the enantiomer asymmetry.
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Affiliation(s)
- Jérémy R Rouxel
- Department of Chemistry, University of California , Irvine, California 92697-2025, USA
| | - Markus Kowalewski
- Department of Chemistry, University of California , Irvine, California 92697-2025, USA
| | - Shaul Mukamel
- Department of Chemistry, University of California , Irvine, California 92697-2025, USA
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82
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Juhin A, Sainctavit P, Ollefs K, Sikora M, Filipponi A, Glatzel P, Wilhelm F, Rogalev A. X-ray magnetic circular dichroism measured at the Fe K-edge with a reduced intrinsic broadening: x-ray absorption spectroscopy versus resonant inelastic x-ray scattering measurements. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:505202. [PMID: 27783570 DOI: 10.1088/0953-8984/28/50/505202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
X-ray magnetic circular dichroism is measured at the Fe K pre-edge in yttrium iron garnet using two different procedures that allow reducing the intrinsic broadening due to the 1s corehole lifetime. First, deconvolution of XMCD data measured in total fluorescence yield (TFY) with an extremely high signal-to-noise ratio enables a factor of 2.4 to be gained in the XMCD intensity. Ligand field multiplet calculations performed with different values of intrinsic broadening show that deconvolving such high quality XMCD data is similar to reducing the lifetime broadening from a 1s corehole to a 2p corehole. Second, MCD is measured by resonant inelastic x-ray scattering spectroscopy as a function of incident energy and emission energy. Selection of a fixed emission energy, instead of using the TFY, allows enhancing the MCD intensity up to a factor of ∼4.7. However, this significantly changes the spectral shape of the XMCD signal, which cannot be interpreted any more as an absorption spectrum.
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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 UMR206, 4 Place Jussieu, F-75005 Paris, France
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83
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Zamudio-Bayer V, Lindblad R, Bülow C, Leistner G, Terasaki A, V Issendorff B, Lau JT. Electronic ground state of Ni 2. J Chem Phys 2016; 145:194302. [PMID: 27875883 DOI: 10.1063/1.4967821] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The Φ9/24 ground state of the Ni2+ diatomic molecular cation is determined experimentally from temperature and magnetic-field-dependent x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap, where an electronic and rotational temperature of 7.4±0.2 K was reached by buffer gas cooling of the molecular ion. The contribution of the spin dipole operator to the x-ray magnetic circular dichroism spin sum rule amounts to 7Tz=0.17±0.06μB per atom, approximately 11% of the spin magnetic moment. We find that, in general, homonuclear diatomic molecular cations of 3d transition metals seem to adopt maximum spin magnetic moments in their electronic ground states.
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Affiliation(s)
- V Zamudio-Bayer
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - R Lindblad
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - C Bülow
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - G Leistner
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - A Terasaki
- Cluster Research Laboratory, Toyota Technological Institute, 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan
| | - B V Issendorff
- Physikalisches Institut, Universität Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
| | - J T Lau
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
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84
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Size dependent microbial oxidation and reduction of magnetite nano- and micro-particles. Sci Rep 2016; 6:30969. [PMID: 27492680 PMCID: PMC4974511 DOI: 10.1038/srep30969] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 07/12/2016] [Indexed: 01/30/2023] Open
Abstract
The ability for magnetite to act as a recyclable electron donor and acceptor for Fe-metabolizing bacteria has recently been shown. However, it remains poorly understood whether microbe-mineral interfacial electron transfer processes are limited by the redox capacity of the magnetite surface or that of whole particles. Here we examine this issue for the phototrophic Fe(II)-oxidizing bacteria Rhodopseudomonas palustris TIE-1 and the Fe(III)-reducing bacteria Geobacter sulfurreducens, comparing magnetite nanoparticles (d ≈ 12 nm) against microparticles (d ≈ 100–200 nm). By integrating surface-sensitive and bulk-sensitive measurement techniques we observed a particle surface that was enriched in Fe(II) with respect to a more oxidized core. This enables microbial Fe(II) oxidation to occur relatively easily at the surface of the mineral suggesting that the electron transfer is dependent upon particle size. However, microbial Fe(III) reduction proceeds via conduction of electrons into the particle interior, i.e. it can be considered as more of a bulk electron transfer process that is independent of particle size. The finding has potential implications on the ability of magnetite to be used for long range electron transport in soils and sediments.
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85
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Liu W, Zhou Q, Chen Q, Niu D, Zhou Y, Xu Y, Zhang R, Wang J, van der Laan G. Probing the Buried Magnetic Interfaces. ACS APPLIED MATERIALS & INTERFACES 2016; 8:5752-5757. [PMID: 26887429 DOI: 10.1021/acsami.5b11438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Understanding magnetism in ferromagnetic metal/semiconductor (FM/SC) heterostructures is important to the development of the new-generation spin field-effect transistor. Here, we report an element-specific X-ray magnetic circular dichroism study of the interfacial magnetic moments for two FM/SC model systems, namely, Co/GaAs and Ni/GaAs, which was enabled using a specially designed FM1/FM2/SC superstructure. We observed a robust room temperature magnetization of the interfacial Co, while that of the interfacial Ni was strongly diminished down to 5 K because of hybridization of the Ni d(eg) and GaAs sp(3) states. The validity of the selected method was confirmed by first-principles calculations, showing only small deviations (<0.02 and <0.07 μB/atom for Co/GaAs and Ni/GaAs, respectively) compared to the real FM/SC interfaces. Our work proved that the electronic structure and magnetic ground state of the interfacial FM2 is not altered when the topmost FM2 is replaced by FM1 and that this model is applicable generally for probing the buried magnetic interfaces in the advanced spintronic materials..
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Affiliation(s)
- Wenqing Liu
- York-Nanjing Joint Center for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York YO10 5DD, U.K
- Department of Physics, The University of Hong Kong , Pokfulam, Hong Kong
| | - Qionghua Zhou
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Qian Chen
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Daxin Niu
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York YO10 5DD, U.K
| | - Yan Zhou
- York-Nanjing Joint Center for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
- Department of Physics, The University of Hong Kong , Pokfulam, Hong Kong
| | - Yongbing Xu
- York-Nanjing Joint Center for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York YO10 5DD, U.K
| | - Rong Zhang
- York-Nanjing Joint Center for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
| | - Jinlan Wang
- Department of Physics, Southeast University , Nanjing 211189, China
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86
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Figueroa AI, van der Laan G, Harrison SE, Cibin G, Hesjedal T. Oxidation Effects in Rare Earth Doped Topological Insulator Thin Films. Sci Rep 2016; 6:22935. [PMID: 26956771 PMCID: PMC4783712 DOI: 10.1038/srep22935] [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: 12/01/2015] [Accepted: 02/25/2016] [Indexed: 11/23/2022] Open
Abstract
The breaking of time-reversal symmetry (TRS) in topological insulators is a prerequisite for unlocking their exotic properties and for observing the quantum anomalous Hall effect (QAHE). The incorporation of dopants which exhibit magnetic long-range order is the most promising approach for TRS-breaking. REBiTe3, wherein 50% of the Bi is substitutionally replaced by a RE atom (RE = Gd, Dy, and Ho), is a predicted QAHE system. Despite the low solubility of REs in bulk crystals of a few %, highly doped thin films have been demonstrated, which are free of secondary phases and of high crystalline quality. Here we study the effects of exposure to atmosphere of rare earth-doped Bi2(Se, Te)3 thin films using x-ray absorption spectroscopy. We demonstrate that these RE dopants are all trivalent and effectively substitute for Bi3+ in the Bi2(Se, Te)3 matrix. We find an unexpected high degree of sample oxidation for the most highly doped samples, which is not restricted to the surface of the films. In the low-doping limit, the RE-doped films mostly show surface oxidation, which can be prevented by surface passivation, encapsulation, or in-situ cleaving to recover the topological surface state.
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Affiliation(s)
- A I Figueroa
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot, OX11 0DE, United Kingdom
| | - G van der Laan
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot, OX11 0DE, United Kingdom
| | - S E Harrison
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom.,Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - G Cibin
- Diamond Light Source, Didcot, OX11 0DE, United Kingdom
| | - T Hesjedal
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom.,Diamond Light Source, Didcot, OX11 0DE, United Kingdom
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87
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Dreiser J, Pacchioni GE, Donati F, Gragnaniello L, Cavallin A, Pedersen KS, Bendix J, Delley B, Pivetta M, Rusponi S, Brune H. Out-of-Plane Alignment of Er(trensal) Easy Magnetization Axes Using Graphene. ACS NANO 2016; 10:2887-2892. [PMID: 26814851 DOI: 10.1021/acsnano.5b08178] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We have studied Er(trensal) single-ion magnets adsorbed on graphene/Ru(0001), on graphene/Ir(111), and on bare Ru(0001) by scanning tunneling microscopy and X-ray absorption spectroscopy. On graphene, the molecules self-assemble into dense and well-ordered islands with their magnetic easy axes perpendicular to the surface. In contrast, on bare Ru(0001), the molecules are disordered, exhibiting only weak directional preference of the easy magnetization axis. The perfect out-of-plane alignment of the easy axes on graphene results from the molecule-molecule interaction, which dominates over the weak adsorption on the graphene surface. Our results demonstrate that the net magnetic properties of a molecular submonolayer can be tuned using a graphene spacer layer, which is attractive for hybrid molecule-inorganic spintronic devices.
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Affiliation(s)
- Jan Dreiser
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Giulia E Pacchioni
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Fabio Donati
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Luca Gragnaniello
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Alberto Cavallin
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Kasper S Pedersen
- CNRS, CRPP, UPR 8641 and CNRS, ICMCB, UPR 9014, 33600 Pessac, France
| | - Jesper Bendix
- Department of Chemistry, University of Copenhagen , 2100 Copenhagen, Denmark
| | | | - Marina Pivetta
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Stefano Rusponi
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Harald Brune
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
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88
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Zamudio-Bayer V, Hirsch K, Langenberg A, Ławicki A, Terasaki A, v. Issendorff B, Lau JT. Electronic ground states of Fe2+ and Co2+ as determined by x-ray absorption and x-ray magnetic circular dichroism spectroscopy. J Chem Phys 2015; 143:244318. [DOI: 10.1063/1.4939078] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- V. Zamudio-Bayer
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
- Physikalisches Institut, Universität Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
| | - K. Hirsch
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - A. Langenberg
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - A. Ławicki
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - A. Terasaki
- Cluster Research Laboratory, Toyota Technological Institute, 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan
- Department of Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - B. v. Issendorff
- Physikalisches Institut, Universität Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
| | - J. T. Lau
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
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89
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Chen T, Liu W, Zheng F, Gao M, Pan X, van der Laan G, Wang X, Zhang Q, Song F, Wang B, Wang B, Xu Y, Wang G, Zhang R. High-Mobility Sm-Doped Bi2 Se3 Ferromagnetic Topological Insulators and Robust Exchange Coupling. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:4823-4829. [PMID: 26178149 DOI: 10.1002/adma.201501254] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/29/2015] [Indexed: 06/04/2023]
Abstract
High-mobility (Smx Bi1-x )2 Se3 topological insulators (with x = 0.05) show a Curie temperature of about 52 K, and the carrier concentration and Fermi wave vector can be manipulated by intentional Te introduction with no significant influence on the Curie temperature. The origin of the ferromagnetism is attributed to the trivalent Sm dopant, as confirmed by X-ray magnetic circular dichroism and first-principles calculations. The carrier concentration is on the order of 10(19) cm(-3) and the mobility can reach about 7200 cm(2) V(-1) s(-1) with pronounced Shubnikov-de Haas oscillations.
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Affiliation(s)
- Taishi Chen
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, P. R. China
- Department of Physics, Nanjing University, Nanjing, 210093, P. R. China
| | - Wenqing Liu
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, P. R. China
- School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
- Department of Electronics, University of York, York, YO10 5DD, UK
| | - Fubao Zheng
- Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yancheng, 224051, P. R. China
| | - Ming Gao
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, P. R. China
- School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Xingchen Pan
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, P. R. China
- Department of Physics, Nanjing University, Nanjing, 210093, P. R. China
| | | | - Xuefeng Wang
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, P. R. China
- School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Qinfang Zhang
- Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yancheng, 224051, P. R. China
| | - Fengqi Song
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, P. R. China
- Department of Physics, Nanjing University, Nanjing, 210093, P. R. China
| | - Baigeng Wang
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, P. R. China
- Department of Physics, Nanjing University, Nanjing, 210093, P. R. China
| | - Baolin Wang
- Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yancheng, 224051, P. R. China
| | - Yongbing Xu
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, P. R. China
- School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
- Department of Electronics, University of York, York, YO10 5DD, UK
| | - Guanghou Wang
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, P. R. China
- Department of Physics, Nanjing University, Nanjing, 210093, P. R. China
| | - Rong Zhang
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, P. R. China
- School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
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90
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Fischer P, Ohldag H. X-rays and magnetism. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2015; 78:094501. [PMID: 26288956 DOI: 10.1088/0034-4885/78/9/094501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Magnetism is among the most active and attractive areas in modern solid state physics because of intriguing phenomena interesting to fundamental research and a manifold of technological applications. State-of-the-art synthesis of advanced magnetic materials, e.g. in hybrid structures paves the way to new functionalities. To characterize modern magnetic materials and the associated magnetic phenomena, polarized x-rays have emerged as unique probes due to their specific interaction with magnetic materials. A large variety of spectroscopic and microscopic techniques have been developed to quantify in an element, valence and site-sensitive way properties of ferro-, ferri-, and antiferromagnetic systems, such as spin and orbital moments, and to image nanoscale spin textures and their dynamics with sub-ns time and almost 10 nm spatial resolution. The enormous intensity of x-rays and their degree of coherence at next generation x-ray facilities will open the fsec time window to magnetic studies addressing fundamental time scales in magnetism with nanometer spatial resolution. This review will give an introduction into contemporary topics of nanoscale magnetic materials and provide an overview of analytical spectroscopy and microscopy tools based on x-ray dichroism effects. Selected examples of current research will demonstrate the potential and future directions of these techniques.
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Affiliation(s)
- Peter Fischer
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720, USA. Physics Department, University of California Santa Cruz, 1156 High St, Santa Cruz, CA 94056, USA
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92
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Zhang W, Zhang D, Wong PKJ, Yuan H, Jiang S, van der Laan G, Zhai Y, Lu Z. Selective Tuning of Gilbert Damping in Spin-Valve Trilayer by Insertion of Rare-Earth Nanolayers. ACS APPLIED MATERIALS & INTERFACES 2015; 7:17070-17075. [PMID: 26177747 DOI: 10.1021/acsami.5b03595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Selective tuning of the Gilbert damping constant, α, in a NiFe/Cu/FeCo spin-valve trilayer has been achieved by inserting different rare-earth nanolayers adjacent to the ferromagnetic layers. Frequency dependent analysis of the ferromagnetic resonances shows that the initially small magnitude of α in the NiFe and FeCo layers is improved by Tb and Gd insertions to various amounts. Using the element-specific technique of X-ray magnetic circular dichroism, we find that the observed increase in α can be attributed primarily to the orbital moment enhancement of Ni and Co, rather than that of Fe. The amplitude of the enhancement depends on the specific rare-earth element, as well as on the lattice and electronic band structure of the transition metals. Our results demonstrate an effective way for individual control of the magnetization dynamics in the different layers of the spin-valve sandwich structures, which will be important for practical applications in high-frequency spintronic devices.
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Affiliation(s)
- Wen Zhang
- †Department of Physics, Southeast University, Nanjing 211189, China
| | - Dong Zhang
- †Department of Physics, Southeast University, Nanjing 211189, China
| | - Ping Kwan Johnny Wong
- §Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
- ∥NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands
| | - Honglei Yuan
- †Department of Physics, Southeast University, Nanjing 211189, China
| | - Sheng Jiang
- †Department of Physics, Southeast University, Nanjing 211189, China
| | - Gerrit van der Laan
- ⊥Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE, United Kingdom
| | - Ya Zhai
- †Department of Physics, Southeast University, Nanjing 211189, China
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93
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Dreiser J. Molecular lanthanide single-ion magnets: from bulk to submonolayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:183203. [PMID: 25893740 DOI: 10.1088/0953-8984/27/18/183203] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Single-ion magnets (SIMs) are mononuclear molecular complexes exhibiting slow relaxation of magnetization. They are currently attracting a lot of interest because of potential applications in spintronics and quantum information processing. However, exploiting SIMs in, e.g. molecule-inorganic hybrid devices requires a fundamental understanding of the effects of molecule-substrate interactions on the SIM magnetic properties. In this review the properties of lanthanide SIMs in the bulk crystalline phase and deposited on surfaces in the (sub)monolayer regime are discussed. As a starting point trivalent lanthanide ions in a ligand field will be described, and the challenges in characterizing the ligand field are illustrated with a focus on several spectroscopic techniques which are able to give direct information on the ligand-field split energy levels. Moreover, the dominant mechanisms of magnetization relaxation in the bulk phase are discussed followed by an overview of SIMs relevant for surface deposition. Further, a short introduction will be given on x-ray absorption spectroscopy, x-ray magnetic circular dichroism and scanning tunneling microscopy. Finally, the recent experiments on surface-deposited SIMs will be reviewed, along with a discussion of future perspectives.
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Affiliation(s)
- J Dreiser
- Ecole Polytechnique Fédérale de Lausanne, ICMP, Station 3, CH-1015 Lausanne, Switzerland. Paul Scherrer Institut, Swiss Light Source, CH-5232 Villigen PSI, Switzerland
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94
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Vaz CAF, Walker FJ, Ahn CH, Ismail-Beigi S. Intrinsic interfacial phenomena in manganite heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:123001. [PMID: 25721578 DOI: 10.1088/0953-8984/27/12/123001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We review recent advances in our understanding of interfacial phenomena that emerge when dissimilar materials are brought together at atomically sharp and coherent interfaces. In particular, we focus on phenomena that are intrinsic to the interface and review recent work carried out on perovskite manganites interfaces, a class of complex oxides whose rich electronic properties have proven to be a useful playground for the discovery and prediction of novel phenomena.
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Affiliation(s)
- C A F Vaz
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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95
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Liu S, Li LL, Li H, Gao HL, Cui JZ, Cheng P. Slow magnetic relaxation in a lanthanide helix chain compound [Dy(HNA)(NA)2(NO3)]n (HNA = nicotinic acid). Dalton Trans 2015; 44:6169-74. [DOI: 10.1039/c5dt00205b] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A racemic helix chain Dy3+ compound 1 bridged by μ1,3-COO groups was synthesized, which showed slow magnetic relaxation behaviour.
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Affiliation(s)
- Shuang Liu
- Department of Chemistry
- Tianjin University
- Tianjin
- China
| | - Lei-Lei Li
- Department of Chemistry
- Key Laboratory of Advanced Energy Material Chemistry
- MOE
- and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
| | - Han Li
- Department of Chemistry
- Key Laboratory of Advanced Energy Material Chemistry
- MOE
- and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
| | - Hong-Ling Gao
- Department of Chemistry
- Tianjin University
- Tianjin
- China
| | | | - Peng Cheng
- Department of Chemistry
- Key Laboratory of Advanced Energy Material Chemistry
- MOE
- and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
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