1
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Backes D, Fujita R, Veiga LSI, Mayoh DA, Wood GDA, Dhesi SS, Balakrishnan G, van der Laan G, Hesjedal T. Valence-state mixing and reduced magnetic moment inFe3-δGeTe2single crystals with varying Fe content probed by x-ray spectroscopy. NANOTECHNOLOGY 2024; 35:395709. [PMID: 38959868 DOI: 10.1088/1361-6528/ad5e87] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 07/03/2024] [Indexed: 07/05/2024]
Abstract
We present a spectroscopic study of the magnetic properties ofFe3-δGeTe2single crystals with varying Fe content, achieved by tuning the stoichiometry of the crystals. We carried out x-ray absorption spectroscopy and analyzed the x-ray circular magnetic dichroism spectra using the sum rules, to determine the orbital and spin magnetic moments of the materials. We find a clear reduction of the spin and orbital magnetic moment with increasing Fe deficiency. Magnetic susceptibility measurements show that the reduction in magnetization is accompanied by a reduced Curie temperature. Multiplet calculations reveal that the Fe2+state increasingly mixes with a higher valence state when the Fe deficiency is increased. This effect is correlated with the weakening of the magnetic moment. As single crystals are the base material for exfoliation processes, our results are relevant for the assembly of 2D magnetic heterostructures.
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Affiliation(s)
- D Backes
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - R Fujita
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - L S I Veiga
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - D A Mayoh
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - G D A Wood
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - S S Dhesi
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - G Balakrishnan
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - G van der Laan
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - T Hesjedal
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
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2
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Sun S, Gu B, Hu H, Lu L, Tang D, Chernyak VY, Li X, Mukamel S. Direct Probe of Conical Intersection Photochemistry by Time-Resolved X-ray Magnetic Circular Dichroism. J Am Chem Soc 2024. [PMID: 38989850 DOI: 10.1021/jacs.4c03033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
The direct probing of photochemical dynamics by detecting the electronic coherence generated during passage through conical intersections is an intriguing challenge. The weak coherence signal and the difficulty in preparing purely excited wave packets that exclude coherence from other sources make it experimentally challenging. We propose to use time-resolved X-ray magnetic circular dichroism to probe the wave packet dynamics around the conical intersection. The magnetic field amplifies the relative strength of the electronic coherence signal compared to populations through the magnetic field response anisotropy. More importantly, since the excited state relaxation through conical intersections involves a change of parity, the magnetic coupling matches the symmetry of the response function with the electronic coherence, making the coherence signal only sensitive to the conical intersection induced coherence and excludes the pump pulse induced coherence between the ground state and excited state. In this theoretical study, we apply this technique to the photodissociation dynamics of a pyrrole molecule and demonstrate its capability of probing electronic coherence at a conical intersection as well as population transfer. We demonstrate that a magnetic field can be effectively used to extract novel information about electron and nuclear molecular dynamics.
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Affiliation(s)
- Shichao Sun
- Department of Chemistry, University of California, Irvine, California 92697, United states
- Departmnet of Physics and Astronomy, University of California, Irvine, California 92697, United States
| | - Bing Gu
- Department of Chemistry and Department of Physics, Westlake University, Hangzhou, Zhejiang 310030, China
| | - Hang Hu
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Lixin Lu
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Diandong Tang
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Vladimir Y Chernyak
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
- Department of Mathematics, Wayne State University, 656 West Kirby, Detroit, Michigan 48202, United States
| | - Xiaosong Li
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Shaul Mukamel
- Department of Chemistry, University of California, Irvine, California 92697, United states
- Departmnet of Physics and Astronomy, University of California, Irvine, California 92697, United States
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3
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Melnikov AR, Ivanov MY, Samsonenko AA, Getmanov YV, Nikovskiy IA, Matiukhina AK, Zorina-Tikhonova EN, Voronina JK, Goloveshkin AS, Babeshkin KA, Efimov NN, Kiskin MA, Eremenko IL, Fedin MV, Veber SL. Inductive detection of temperature-induced magnetization dynamics of molecular spin systems. J Chem Phys 2024; 160:224201. [PMID: 38856059 DOI: 10.1063/5.0211936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 05/24/2024] [Indexed: 06/11/2024] Open
Abstract
The development and technological applications of molecular spin systems require versatile experimental techniques to characterize and control their static and dynamic magnetic properties. In the latter case, bulk spectroscopic and magnetometric techniques, such as AC magnetometry and pulsed electron paramagnetic resonance, are usually employed, showing high sensitivity, wide dynamic range, and flexibility. They are based on creating a nonequilibrium state either by changing the magnetic field or by applying resonant microwave radiation. Another possible source of perturbation is a laser pulse that rapidly heats the sample. This approach has proven to be one of the most useful techniques for studying the kinetics and mechanism of chemical and biochemical reactions. Inspired by these works, we propose an inductive detection of temperature-induced magnetization dynamics as applied to the study of molecular spin systems and describe the general design and construction of a particular induction probehead, taking into account the constraints imposed by the cryostat and electromagnet. To evaluate the performance, several coordination compounds of VO2+, Co2+, and Dy3+ were investigated using low-energy pulses of a terahertz free electron laser of the Novosibirsk free electron laser facility as a heat source. All measured magnetization dynamics were qualitatively or quantitatively described using a proposed basic theoretical model and compared with the data obtained by alternating current magnetometry. Based on the results of the research, the possible scope of applications of inductive detection and its advantages and disadvantages in comparison with standard methods are discussed.
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Affiliation(s)
- Anatoly R Melnikov
- International Tomography Center of the Siberian Branch of the Russian Academy of Sciences, 3a, Institutskaya Str., Novosibirsk 630090, Russian Federation
- Novosibirsk State University, 1, Pirogova Str., Novosibirsk 630090, Russian Federation
| | - Mikhail Yu Ivanov
- International Tomography Center of the Siberian Branch of the Russian Academy of Sciences, 3a, Institutskaya Str., Novosibirsk 630090, Russian Federation
| | - Arkady A Samsonenko
- International Tomography Center of the Siberian Branch of the Russian Academy of Sciences, 3a, Institutskaya Str., Novosibirsk 630090, Russian Federation
- Novosibirsk State University, 1, Pirogova Str., Novosibirsk 630090, Russian Federation
| | - Yaroslav V Getmanov
- Novosibirsk State University, 1, Pirogova Str., Novosibirsk 630090, Russian Federation
- Budker Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences, 11, Acad. Lavrentieva Ave., Novosibirsk 630090, Russian Federation
| | - Igor A Nikovskiy
- A.N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences, 28, Vavilova Str., Moscow 119334, Russian Federation
| | - Anna K Matiukhina
- N.S. Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31, Leninsky Ave., Moscow 119991, Russian Federation
| | - Ekaterina N Zorina-Tikhonova
- N.S. Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31, Leninsky Ave., Moscow 119991, Russian Federation
| | - Julia K Voronina
- N.S. Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31, Leninsky Ave., Moscow 119991, Russian Federation
| | - Alexander S Goloveshkin
- A.N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences, 28, Vavilova Str., Moscow 119334, Russian Federation
| | - Konstantin A Babeshkin
- N.S. Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31, Leninsky Ave., Moscow 119991, Russian Federation
| | - Nikolay N Efimov
- N.S. Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31, Leninsky Ave., Moscow 119991, Russian Federation
| | - Mikhail A Kiskin
- N.S. Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31, Leninsky Ave., Moscow 119991, Russian Federation
| | - Igor L Eremenko
- N.S. Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31, Leninsky Ave., Moscow 119991, Russian Federation
| | - Matvey V Fedin
- International Tomography Center of the Siberian Branch of the Russian Academy of Sciences, 3a, Institutskaya Str., Novosibirsk 630090, Russian Federation
- Novosibirsk State University, 1, Pirogova Str., Novosibirsk 630090, Russian Federation
| | - Sergey L Veber
- International Tomography Center of the Siberian Branch of the Russian Academy of Sciences, 3a, Institutskaya Str., Novosibirsk 630090, Russian Federation
- Novosibirsk State University, 1, Pirogova Str., Novosibirsk 630090, Russian Federation
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4
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Fan R, Aboljadayel ROM, Alsaeed K, Bencok P, Burn DM, Hindmarch AT, Steadman P. Measuring magnetic hysteresis curves with polarized soft X-ray resonant reflectivity. JOURNAL OF SYNCHROTRON RADIATION 2024; 31:493-507. [PMID: 38597745 DOI: 10.1107/s160057752400119x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 02/03/2024] [Indexed: 04/11/2024]
Abstract
Calculations and measurements of polarization-dependent soft X-ray scattering intensity are presented during a magnetic hysteresis cycle. It is confirmed that the dependence of the intensity on the magnetic moment can be linear, quadratic or a combination of both, depending on the polarization of the incident X-ray beam and the direction of the magnetic moment. With a linearly polarized beam, the scattered intensity will have a purely quadratic dependence on the magnetic moment when the magnetic moment is parallel to the scattering plane. However, with the magnetic moment perpendicular to the scattering plane, there is also a linear component. This means that, when measuring the hysteresis with linear polarization during a hysteresis cycle, the intensity will be an even function of the applied field when the change in the magnetic moment (and field) is confined within the scattering plane but becomes more complicated when the magnetic moment is out of the scattering plane. Furthermore, with circular polarization, the dependence of the scattered intensity on the moment is a combination of linear and quadratic. With the moment parallel to the scattering plane, the linear component changes with the helicity of the incident beam. Surprisingly, in stark contrast to absorption studies, even when the magnetic moment is perpendicular to the scattering plane there is still a dependence on the moment with a linear component. This linear component is completely independent of the helicity of the beam, meaning that the hysteresis loops will not be inverted with helicity.
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Affiliation(s)
- Raymond Fan
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0DE, United Kingdom
| | - Razan O M Aboljadayel
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0DE, United Kingdom
| | - Kalel Alsaeed
- Department of Physics, Durham University, Durham DH1 3LE, United Kingdom
| | - Peter Bencok
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0DE, United Kingdom
| | - David M Burn
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0DE, United Kingdom
| | - Aidan T Hindmarch
- Department of Physics, Durham University, Durham DH1 3LE, United Kingdom
| | - Paul Steadman
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0DE, United Kingdom
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5
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Everett J, Brooks J, Tjendana Tjhin V, Lermyte F, Hands-Portman I, Plascencia-Villa G, Perry G, Sadler PJ, O’Connor PB, Collingwood JF, Telling ND. Label-Free In Situ Chemical Characterization of Amyloid Plaques in Human Brain Tissues. ACS Chem Neurosci 2024; 15:1469-1483. [PMID: 38501754 PMCID: PMC10995949 DOI: 10.1021/acschemneuro.3c00756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 02/20/2024] [Accepted: 03/01/2024] [Indexed: 03/20/2024] Open
Abstract
The accumulation of amyloid plaques and increased brain redox burdens are neuropathological hallmarks of Alzheimer's disease. Altered metabolism of essential biometals is another feature of Alzheimer's, with amyloid plaques representing sites of disturbed metal homeostasis. Despite these observations, metal-targeting disease treatments have not been therapeutically effective to date. A better understanding of amyloid plaque composition and the role of the metals associated with them is critical. To establish this knowledge, the ability to resolve chemical variations at nanometer length scales relevant to biology is essential. Here, we present a methodology for the label-free, nanoscale chemical characterization of amyloid plaques within human Alzheimer's disease tissue using synchrotron X-ray spectromicroscopy. Our approach exploits a C-H carbon absorption feature, consistent with the presence of lipids, to visualize amyloid plaques selectively against the tissue background, allowing chemical analysis to be performed without the addition of amyloid dyes that alter the native sample chemistry. Using this approach, we show that amyloid plaques contain elevated levels of calcium, carbonates, and iron compared to the surrounding brain tissue. Chemical analysis of iron within plaques revealed the presence of chemically reduced, low-oxidation-state phases, including ferromagnetic metallic iron. The zero-oxidation state of ferromagnetic iron determines its high chemical reactivity and so may contribute to the redox burden in the Alzheimer's brain and thus drive neurodegeneration. Ferromagnetic metallic iron has no established physiological function in the brain and may represent a target for therapies designed to lower redox burdens in Alzheimer's disease. Additionally, ferromagnetic metallic iron has magnetic properties that are distinct from the iron oxide forms predominant in tissue, which might be exploitable for the in vivo detection of amyloid pathologies using magnetically sensitive imaging. We anticipate that this label-free X-ray imaging approach will provide further insights into the chemical composition of amyloid plaques, facilitating better understanding of how plaques influence the course of Alzheimer's disease.
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Affiliation(s)
- James Everett
- School
of Pharmacy and Bioengineering, Guy Hilton Research Centre, Keele University, Thornburrow Drive,Stoke-on-Trent,Staffordshire ST4 7QB, U.K.
- School
of Engineering, University of Warwick, Library Road,Coventry CV4 7AL, U.K.
| | - Jake Brooks
- School
of Engineering, University of Warwick, Library Road,Coventry CV4 7AL, U.K.
| | - Vindy Tjendana Tjhin
- School
of Engineering, University of Warwick, Library Road,Coventry CV4 7AL, U.K.
| | - Frederik Lermyte
- School
of Engineering, University of Warwick, Library Road,Coventry CV4 7AL, U.K.
- Department
of Chemistry, Technical University of Darmstadt, Alarich-Weiss-Strasse 4, 64287 Darmstadt, Germany
| | - Ian Hands-Portman
- School
of Life Sciences, University of Warwick, Gibbet Hill Campus,Coventry CV4 7AL, U.K.
| | - Germán Plascencia-Villa
- Department
of Developmental and Regenerative Biology, The University of Texas at San Antonio (UTSA), San Antonio, Texas 78249, United States
| | - George Perry
- Department
of Developmental and Regenerative Biology, The University of Texas at San Antonio (UTSA), San Antonio, Texas 78249, United States
| | - Peter J. Sadler
- Department
of Chemistry, University of Warwick, Library Road,Coventry CV4 7AL, U.K.
| | - Peter B. O’Connor
- Department
of Chemistry, University of Warwick, Library Road,Coventry CV4 7AL, U.K.
| | | | - Neil D. Telling
- School
of Pharmacy and Bioengineering, Guy Hilton Research Centre, Keele University, Thornburrow Drive,Stoke-on-Trent,Staffordshire ST4 7QB, U.K.
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6
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Golosovsky IV, Kibalin IA, Gukasov A, Roca AG, López-Ortega A, Estrader M, Vasilakaki M, Trohidou KN, Hansen TC, Puente-Orench I, Lelièvre-Berna E, Nogués J. Elucidating Individual Magnetic Contributions in Bi-Magnetic Fe 3 O 4 /Mn 3 O 4 Core/Shell Nanoparticles by Polarized Powder Neutron Diffraction. SMALL METHODS 2023; 7:e2201725. [PMID: 37391272 DOI: 10.1002/smtd.202201725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 05/10/2023] [Indexed: 07/02/2023]
Abstract
Heterogeneous bi-magnetic nanostructured systems have had a sustained interest during the last decades owing to their unique magnetic properties and the wide range of derived potential applications. However, elucidating the details of their magnetic properties can be rather complex. Here, a comprehensive study of Fe3 O4 /Mn3 O4 core/shell nanoparticles using polarized neutron powder diffraction, which allows disentangling the magnetic contributions of each of the components, is presented. The results show that while at low fields the Fe3 O4 and Mn3 O4 magnetic moments averaged over the unit cell are antiferromagnetically coupled, at high fields, they orient parallel to each other. This magnetic reorientation of the Mn3 O4 shell moments is associated with a gradual evolution with the applied field of the local magnetic susceptibility from anisotropic to isotropic. Additionally, the magnetic coherence length of the Fe3 O4 cores shows some unusual field dependence due to the competition between the antiferromagnetic interface interaction and the Zeeman energies. The results demonstrate the great potential of the quantitative analysis of polarized neutron powder diffraction for the study of complex multiphase magnetic materials.
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Affiliation(s)
- I V Golosovsky
- National Research Center "Kurchatov Institute", B. P. Konstantinov Petersburg Nuclear Physics Institute, Gatchina, 188300, Russia
| | - I A Kibalin
- Laboratoire Léon Brillouin, CEA-CNRS, CE-Saclay, Gif-sur-Yvette, 91191, France
| | - A Gukasov
- Laboratoire Léon Brillouin, CEA-CNRS, CE-Saclay, Gif-sur-Yvette, 91191, France
| | - A G Roca
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Spain
| | - A López-Ortega
- Departamento de Ciencias, Universidad Pública de Navarra, Pamplona, 31006, Spain
- Institute for Advanced Materials and Mathematics INAMAT2, Universidad Pública de Navarra, Pamplona, 31006, Spain
| | - M Estrader
- Departament de Química Inorgànica i Orgànica, carrer Martí i Franqués 1-11, Universitat de Barcelona, Barcelona, 08028, Spain
- Institut de Nanociència i Nanotecnologia IN2UB, carrer Martí i Franqués 1-11, Universitat de Barcelona, Barcelona, 08028, Spain
| | - M Vasilakaki
- Institute of Nanoscience and Nanotechnology, NCSR "Demokritos", 153 10, Agia Paraskevi, Attiki, 15310, Greece
| | - K N Trohidou
- Institute of Nanoscience and Nanotechnology, NCSR "Demokritos", 153 10, Agia Paraskevi, Attiki, 15310, Greece
| | - T C Hansen
- Institut Laue Langevin, 71 avenue des Martyrs, Grenoble, 38000, France
| | - I Puente-Orench
- Institut Laue Langevin, 71 avenue des Martyrs, Grenoble, 38000, France
- Instituto de NanoCiencia y Materiales de Aragón, Zaragoza, 50009, Spain
| | - E Lelièvre-Berna
- Institut Laue Langevin, 71 avenue des Martyrs, Grenoble, 38000, France
| | - J Nogués
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Spain
- ICREA, Barcelona, 08010, Spain
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7
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Han JK, Baker AA, Lee JRI, McCall SK. Probing strongly exchange coupled magnetic behaviors in soft/hard Ni/CoFe 2O 4 core/shell nanoparticles. NANOSCALE 2023; 15:14782-14789. [PMID: 37548923 DOI: 10.1039/d3nr03478j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Exchange coupling in a model core-shell system is demonstrated as a step on the path to 3d exchange spring magnets. Employing a model system of Ni@CoFe2O4, high quality core-shell nanoparticles were fabricated using a simple two-step method. The microstructural quality was validated using TEM, confirming a well-defined interface between the core and the shell. A strongly temperature dependent two-phase magnetic hysteresis loop was measured, wherein an analysis of step heights indicates coupling of roughly 50% between the core and the shell. Element-specific XMCD hysteresis confirms the presence of exchange coupling, suppressing the superparamagnetism of the Ni core at room temperature, and reaching a coercivity of >6 kOe at 80 K. These results provide a pathway to the development of heterostructured metal-oxide exchange coupled nanoparticles with improved maximum energy product.
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Affiliation(s)
- J K Han
- Critical Materials Institute, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
| | - A A Baker
- Critical Materials Institute, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
| | - J R I Lee
- Critical Materials Institute, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
| | - S K McCall
- Critical Materials Institute, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
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8
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Lv H, da Silva A, Figueroa AI, Guillemard C, Aguirre IF, Camosi L, Aballe L, Valvidares M, Valenzuela SO, Schubert J, Schmidbauer M, Herfort J, Hanke M, Trampert A, Engel-Herbert R, Ramsteiner M, Lopes JMJ. Large-Area Synthesis of Ferromagnetic Fe 5- x GeTe 2 /Graphene van der Waals Heterostructures with Curie Temperature above Room Temperature. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2302387. [PMID: 37231567 DOI: 10.1002/smll.202302387] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 05/10/2023] [Indexed: 05/27/2023]
Abstract
Van der Waals (vdW) heterostructures combining layered ferromagnets and other 2D crystals are promising building blocks for the realization of ultracompact devices with integrated magnetic, electronic, and optical functionalities. Their implementation in various technologies depends strongly on the development of a bottom-up scalable synthesis approach allowing for realizing highly uniform heterostructures with well-defined interfaces between different 2D-layered materials. It is also required that each material component of the heterostructure remains functional, which ideally includes ferromagnetic order above room temperature for 2D ferromagnets. Here, it is demonstrated that the large-area growth of Fe5- x GeTe2 /graphene heterostructures is achieved by vdW epitaxy of Fe5- x GeTe2 on epitaxial graphene. Structural characterization confirms the realization of a continuous vdW heterostructure film with a sharp interface between Fe5- x GeTe2 and graphene. Magnetic and transport studies reveal that the ferromagnetic order persists well above 300 K with a perpendicular magnetic anisotropy. In addition, epitaxial graphene on SiC(0001) continues to exhibit a high electronic quality. These results represent an important advance beyond nonscalable flake exfoliation and stacking methods, thus marking a crucial step toward the implementation of ferromagnetic 2D materials in practical applications.
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Affiliation(s)
- Hua Lv
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V, 10117, Berlin, Germany
| | - Alessandra da Silva
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V, 10117, Berlin, Germany
| | - Adriana I Figueroa
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Spain
| | - Charles Guillemard
- ALBA Synchrotron Light Source, Cerdanyola del Valles, Barcelona, 08290, Spain
| | - Iván Fernández Aguirre
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Spain
- Universitat Autònoma de Barcelona, Bellaterra, Barcelona, 08193, Spain
| | - Lorenzo Camosi
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Spain
| | - Lucia Aballe
- ALBA Synchrotron Light Source, Cerdanyola del Valles, Barcelona, 08290, Spain
| | - Manuel Valvidares
- ALBA Synchrotron Light Source, Cerdanyola del Valles, Barcelona, 08290, Spain
| | - Sergio O Valenzuela
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, 08010, Spain
| | - Jürgen Schubert
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, 52425, Jülich, Germany
| | | | - Jens Herfort
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V, 10117, Berlin, Germany
| | - Michael Hanke
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V, 10117, Berlin, Germany
| | - Achim Trampert
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V, 10117, Berlin, Germany
| | - Roman Engel-Herbert
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V, 10117, Berlin, Germany
| | - Manfred Ramsteiner
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V, 10117, Berlin, Germany
| | - Joao Marcelo J Lopes
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V, 10117, Berlin, Germany
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9
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Misael WA, Severo Pereira Gomes A. Core Excitations of Uranyl in Cs 2UO 2Cl 4 from Relativistic Embedded Damped Response Time-Dependent Density Functional Theory Calculations. Inorg Chem 2023; 62:11589-11601. [PMID: 37432868 DOI: 10.1021/acs.inorgchem.3c01302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2023]
Abstract
X-ray spectroscopies, by their high selectivity and sensitivity to the chemical environment around the atoms probed, provide significant insights into the electronic structures of molecules and materials. Interpreting experimental results requires reliable theoretical models, accounting for environmental, relativistic, electron correlation, and orbital relaxation effects in a balanced manner. In this work, we present a protocol for the simulation of core excited spectra with damped response time-dependent density functional theory based on the Dirac-Coulomb Hamiltonian (4c-DR-TD-DFT), in which environmental effects are accounted for through the frozen density embedding (FDE) method. We showcase this approach for the uranium M4- and L3-edges and oxygen K-edge of the uranyl tetrachloride (UO2Cl42-) unit as found in a host Cs2UO2Cl4 crystal. We have found that the 4c-DR-TD-DFT simulations yield excitation spectra that very closely match the experiment for the uranium M4-edge and the oxygen K-edge, with good agreement for the broad experimental spectra for the L3-edge. By decomposing the complex polarizability in terms of its components, we have been able to correlate our results with angle-resolved spectra. We have observed that for all edges, but in particular the uranium M4-edge, an embedded model in which the chloride ligands are replaced by an embedding potential reproduces rather well the spectral profile obtained for UO2Cl42-. Our results underscore the importance of the equatorial ligands to simulating core spectra at both uranium and oxygen edges.
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Affiliation(s)
- Wilken Aldair Misael
- Univ. Lille, CNRS, UMR 8523-PhLAM-Physique des Lasers Atomes et Molécules, F-59000 Lille, France
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10
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Chen H, Yang HH, Frauhammer T, You H, Sun Q, Nagel P, Schuppler S, Gaspar AB, Real JA, Wulfhekel W. Observation of Exchange Interaction in Iron(II) Spin Crossover Molecules in Contact with Passivated Ferromagnetic Surface of Co/Au(111). SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2300251. [PMID: 36828799 DOI: 10.1002/smll.202300251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Indexed: 06/02/2023]
Abstract
Spin crossover (SCO) complexes sensitively react on changes of the environment by a change in the spin of the central metallic ion making them ideal candidates for molecular spintronics. In particular, the composite of SCO complexes and ferromagnetic (FM) surfaces would allow spin-state switching of the molecules in combination with the magnetic exchange interaction to the magnetic substrate. Unfortunately, when depositing SCO complexes on ferromagnetic surfaces, spin-state switching is blocked by the relatively strong interaction between the adsorbed molecules and the surface. Here, the Fe(II) SCO complex [FeII (Pyrz)2 ] (Pyrz = 3,5-dimethylpyrazolylborate) with sub-monolayer thickness in contact with a passivated FM film of Co on Au(111) is studied. In this case, the molecules preserve thermal spin crossover and at the same time the high-spin species show a sizable exchange interaction of > 0.9 T with the FM Co substrate. These observations provide a feasible design strategy in fabricating SCO-FM hybrid devices.
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Affiliation(s)
- Hongyan Chen
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Hung-Hsiang Yang
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Timo Frauhammer
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Haoran You
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Qing Sun
- Laboratory for Electron Microscopy, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Peter Nagel
- Electron Spectroscopy Group, Institute for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), 76021, Karlsruhe, Germany
- Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany
| | - Stefan Schuppler
- Electron Spectroscopy Group, Institute for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), 76021, Karlsruhe, Germany
- Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany
| | - Ana Belén Gaspar
- Institut de Ciència Molecular (ICMol), Universitat de València, C/Catedrático José Beltrán Martínez 2, 46980, Paterna, Valencia, Spain
| | - José Antonio Real
- Institut de Ciència Molecular (ICMol), Universitat de València, C/Catedrático José Beltrán Martínez 2, 46980, Paterna, Valencia, Spain
| | - Wulf Wulfhekel
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
- Quantum Control Group, Institute for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), 76021, Karlsruhe, Germany
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11
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Burn DM, Lin JC, Fujita R, Achinuq B, Bibby J, Singh A, Frisk A, van der Laan G, Hesjedal T. Spin pumping through nanocrystalline topological insulators. NANOTECHNOLOGY 2023; 34:275001. [PMID: 36947871 DOI: 10.1088/1361-6528/acc663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 03/21/2023] [Indexed: 06/18/2023]
Abstract
The topological surface states (TSSs) in topological insulators (TIs) offer exciting prospects for dissipationless spin transport. Common spin-based devices, such as spin valves, rely on trilayer structures in which a non-magnetic layer is sandwiched between two ferromagnetic (FM) layers. The major disadvantage of using high-quality single-crystalline TI films in this context is that a single pair of spin-momentum locked channels spans across the entire film, meaning that only a very small spin current can be pumped from one FM to the other, along the side walls of the film. On the other hand, using nanocrystalline TI films, in which the grains are large enough to avoid hybridization of the TSSs, will effectively increase the number of spin channels available for spin pumping. Here, we used an element-selective, x-ray based ferromagnetic resonance technique to demonstrate spin pumping from a FM layer at resonance through the TI layer and into the FM spin sink.
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Affiliation(s)
- David M Burn
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Jheng-Cyuan Lin
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
| | - Ryuji Fujita
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
| | - Barat Achinuq
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
| | - Joshua Bibby
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
| | - Angadjit Singh
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
| | - Andreas Frisk
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Gerrit van der Laan
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire 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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12
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Alam M, Chatterjee S. B-site order/disorder in A 2BB'O 6and its correlation with their magnetic property. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:223001. [PMID: 36888997 DOI: 10.1088/1361-648x/acc295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 03/08/2023] [Indexed: 06/18/2023]
Abstract
The disorder in any system affects their physical behavior. In this scenario, we report the possibility of disorder in A2BB'O6oxides and their effect on different magnetic properties. These systems show anti-site disorder by interchanging B and B' elements from their ordered position and giving rise to an anti-phase boundary. The presence of disorder leads to a reduction in saturationMand magnetic transition temperature. The disorder prevents the system from sharp magnetic transition which originates short-range clustered phase (or Griffiths phase) in the paramagnetic region just above the long-range magnetic transition temperature. Further, we report that the presence of anti-site disorder and anti-phase boundary in A2BB'O6oxides give different interesting magnetic phases like metamagnetic transition, spin-glass, exchange bias, magnetocaloric effect, magnetodielectric, magnetoresistance, spin-phonon coupling, etc.
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Affiliation(s)
- Mohd Alam
- Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India
| | - Sandip Chatterjee
- Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India
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13
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Ohsumi H, Fujikawa Y, Liu L, Kotani Y, Nakamura T. Post-acquisition upsampling method for scanning x-ray microscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:033701. [PMID: 37012746 DOI: 10.1063/5.0098245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 01/13/2023] [Indexed: 06/19/2023]
Abstract
A method of post-acquisition upsampling for scanning x-ray microscopy is developed in this study to improve the spatial resolution beyond the Nyquist frequency as determined by the intervals of a raster scan grid. The proposed method is applicable only when the probe beam size is not negligibly small compared with the pixels that constitute a raster micrograph-the Voronoi cells of a scan grid. The unconvoluted spatial variation in a photoresponse is estimated by solving a stochastic inverse problem at a higher resolution than that at which the data are acquired. This is followed by a rise in the spatial cutoff frequency due to a reduction in the noise floor. The practicability of the proposed method was verified by applying it to raster micrographs of x-ray absorption in Nd-Fe-B sintered magnets. The improvement thus achieved in spatial resolution was numerically demonstrated via spectral analysis by using the discrete Fourier transform. The authors also argue for a reasonable decimation scheme for the spatial sampling interval in relation to an ill-posed inverse problem and aliasing. The computer-assisted enhancement in the viability of scanning x-ray magnetic circular dichroism microscopy was illustrated by visualizing magnetic field-induced changes in domain patterns of the Nd2Fe14B main-phase.
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Affiliation(s)
- Hiroyuki Ohsumi
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | | | - Lihua Liu
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Yoshinori Kotani
- Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Tetsuya Nakamura
- Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
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14
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Powalla L, Birch MT, Litzius K, Wintz S, Yasin FS, Turnbull LA, Schulz F, Mayoh DA, Balakrishnan G, Weigand M, Yu X, Kern K, Schütz G, Burghard M. Seeding and Emergence of Composite Skyrmions in a van der Waals Magnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208930. [PMID: 36637996 DOI: 10.1002/adma.202208930] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 12/14/2022] [Indexed: 06/17/2023]
Abstract
Topological charge plays a significant role in a range of physical systems. In particular, observations of real-space topological objects in magnetic materials have been largely limited to skyrmions - states with a unitary topological charge. Recently, more exotic states with varying topology, such as antiskyrmions, merons, or bimerons and 3D states such as skyrmion strings, chiral bobbers, and hopfions, have been experimentally reported. Along these lines, the realization of states with higher-order topology has the potential to open new avenues of research in topological magnetism and its spintronic applications. Here, real-space imaging of such spin textures, including skyrmion, skyrmionium, skyrmion bag, and skyrmion sack states, observed in exfoliated flakes of the van der Waals magnet Fe3-x GeTe2 (FGT) is reported. These composite skyrmions may emerge from seeded, loop-like states condensed into the stripe domain structure, demonstrating the possibility to realize spin textures with arbitrary integer topological charge within exfoliated flakes of 2D magnets. The general nature of the formation mechanism motivates the search for composite skyrmion states in both well-known and new magnetic materials, which may yet reveal an even richer spectrum of higher-order topological objects.
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Affiliation(s)
- Lukas Powalla
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
| | - Max T Birch
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Kai Litzius
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Sebastian Wintz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Fehmi S Yasin
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Luke A Turnbull
- Department of Physics, Durham University, Durham, DH1 3LE, UK
| | - Frank Schulz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Daniel A Mayoh
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | | | - Markus Weigand
- Institute Nanospectroscopy, Helmholtz-Zentrum Berlin, 12489, Berlin, Germany
| | - Xiuzhen Yu
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Klaus Kern
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
- Institut de Physique, École Polytechnique Fédérale de Lausanne, Lausanne, 1015, Switzerland
| | - Gisela Schütz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Marko Burghard
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
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15
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Tereba N, Muzioł TM, Wiśniewska J, Podgajny R, Bieńko A, Wrzeszcz G. Structural Diversity, XAS and Magnetism of Copper(II)-Nickel(II) Heterometallic Complexes Based on the [Ni(NCS) 6] 4- Unit. MATERIALS (BASEL, SWITZERLAND) 2023; 16:731. [PMID: 36676467 PMCID: PMC9861906 DOI: 10.3390/ma16020731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/05/2023] [Accepted: 01/07/2023] [Indexed: 06/17/2023]
Abstract
The new heterometallic compounds, [{Cu(pn)2}2Ni(NCS)6]n·2nH2O (1), [{CuII(trien)}2Ni(NCS)6CuI(NCS)]n (2) and [Cu(tren)(NCS)]4[Ni(NCS)6] (3) (pn = 1,2-diaminopropane, trien = triethylenetetramine and tren = tris(2-aminoethylo)amine), were obtained and characterized by X-ray analysis, IR spectra, XAS and magnetic measurements. Compounds 1, 2 and 3 show the structural diversity of 2D, 1D and 0D compounds, respectively. Depending on the polyamine used, different coordination polyhedron for Cu(II) was found, i.e., distorted octahedral (1), square pyramidal (2) and trigonal bipyramidal (3), whereas coordination polyhedron for nickel(II) was always octahedral. It provides an approach for tailoring magnetic properties by proper selection of auxiliary ligands determining the topology. In 1, thiocyanate ligands form bridges between the copper and nickel ions, creating 2D layers of sql topology with weak ferromagnetic interactions. Compound 2 is a mixed-valence copper coordination polymer and shows the rare ladder topology of 1D chains decorated with [CuII(tren)]2+ antennas as the side chains attached to nickel(II). The ladder rails are formed by alternately arranged Ni(II) and Cu(I) ions connected by N2 thiocyanate anions and rungs made by N3 thiocyanate. For the Cu(I) ions, the tetrahedral thiocyanate environment mixed N/S donor atoms was found, confirming significant coordination spheres rearrangement occurring at the copper precursor together with the reduction in some Cu(II) to Cu(I). Such topology enables significant simplification of the magnetic properties modeling by assuming magnetic coupling inside {NiIICuII2} trinuclear units separated by diamagnetic [Cu(NCS)(SCN)3]3- linkers. Compound 3 shows three discrete mononuclear units connected by N-H…N and N-H…S hydrogen bonds. Analysis of XAS proves that the average ligand character and the covalency of the unoccupied metal d-based orbitals for copper(II) and nickel(II) increase in the following order: 1 → 2 → 3. In 1 and 2, a weak ferromagnetic coupling between copper(II) and nickel(II) was found, but in 2, additional and stronger antiferromagnetic interaction between copper(II) ions prevailed. Compound 3, as an ionic pair, shows, as expected, a spin-only magnetic moment.
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Affiliation(s)
- Natalia Tereba
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
| | - Tadeusz M. Muzioł
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
| | - Joanna Wiśniewska
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
| | - Robert Podgajny
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Alina Bieńko
- Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, 50-383 Wrocław, Poland
| | - Grzegorz Wrzeszcz
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
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16
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Magnetic molecules on surfaces: SMMs and beyond. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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17
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Powalla L, Birch MT, Litzius K, Wintz S, Schulz F, Weigand M, Scholz T, Lotsch BV, Kern K, Schütz G, Burghard M. Single Skyrmion Generation via a Vertical Nanocontact in a 2D Magnet-Based Heterostructure. NANO LETTERS 2022; 22:9236-9243. [PMID: 36400013 PMCID: PMC9756335 DOI: 10.1021/acs.nanolett.2c01944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 11/07/2022] [Indexed: 06/16/2023]
Abstract
Skyrmions have been well studied in chiral magnets and magnetic thin films due to their potential application in practical devices. Recently, monochiral skyrmions have been observed in two-dimensional van der Waals magnets. Their atomically flat surfaces and capability to be stacked into heterostructures offer new prospects for skyrmion applications. However, the controlled local nucleation of skyrmions within these materials has yet to be realized. Here, we utilize real-space X-ray microscopy to investigate a heterostructure composed of the 2D ferromagnet Fe3GeTe2 (FGT), an insulating hexagonal boron nitride layer, and a graphite top electrode. Upon a stepwise increase of the voltage applied between the graphite and FGT, a vertically conducting pathway can be formed. This nanocontact allows the tunable creation of individual skyrmions via single nanosecond pulses of low current density. Furthermore, time-resolved magnetic imaging highlights the stability of the nanocontact, while our micromagnetic simulations reproduce the observed skyrmion nucleation process.
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Affiliation(s)
- Lukas Powalla
- Max
Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569Stuttgart, Germany
| | - Max T. Birch
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
| | - Kai Litzius
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
| | - Sebastian Wintz
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109Berlin, Germany
| | - Frank Schulz
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
| | - Markus Weigand
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109Berlin, Germany
| | - Tanja Scholz
- Max
Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569Stuttgart, Germany
| | - Bettina V. Lotsch
- Max
Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569Stuttgart, Germany
- University
of Munich (LMU), Butenandtstraße 5-13 (Haus D), 81377München, Germany
| | - Klaus Kern
- Max
Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569Stuttgart, Germany
- Institute
de Physique, École Polytechnique
Fédérale de Lausanne, CH-1015Lausanne, Switzerland
| | - Gisela Schütz
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569Stuttgart, Germany
| | - Marko Burghard
- Max
Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569Stuttgart, Germany
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18
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N’Diaye A, Bordage A, Nataf L, Baudelet F, Rivière E, Bleuzen A. Interplay between Transition-Metal K-edge XMCD and Magnetism in Prussian Blue Analogs. ACS OMEGA 2022; 7:36366-36378. [PMID: 36278067 PMCID: PMC9583310 DOI: 10.1021/acsomega.2c04049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 07/25/2022] [Indexed: 06/16/2023]
Abstract
To disentangle the information contained in transition-metal K-edge X-ray magnetic circular dichroism (XMCD), two series of Prussian blue analogs (PBAs) were investigated as model compounds. The number of 3d electrons and the magnetic orbitals have been varied on both sites of the bimetallic cyanide polymer by combining with the hexacyanoferrate or the hexacyanochromate entities' various divalent metal ions A2+ (Mn2+, Fe2+, Co2+, Ni2+, and Cu2+). These PBA were studied by Fe and Cr X-ray absorption spectroscopy and XMCD. The results, compared to those obtained at the A K-edges in a previous work, show that transition-metal K-edge XMCD is very sensitive to orbital symmetry and can therefore give valuable information on the local structure of the magnetic centers. Expressions of the intensity of the main 1s → 4p contribution to the signal are proposed for all K-edges and all compounds. The results pave the way toward a new tool for molecular materials able to give access to valuable information on the local orientation of the magnetic moments or to better understand the role of 4p orbitals involved in their magnetic properties.
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Affiliation(s)
- Adama N’Diaye
- Institut
de Chimie Moléculaire et des Matériaux d’Orsay,
CNRS, Université Paris-Saclay, 91405Orsay, France
| | - Amélie Bordage
- Institut
de Chimie Moléculaire et des Matériaux d’Orsay,
CNRS, Université Paris-Saclay, 91405Orsay, France
| | - Lucie Nataf
- Synchrotron
SOLEIL, L’Orme des Merisiers, St Aubin, BP 48, F-91192Gif sur Yvette, France
| | - François Baudelet
- Synchrotron
SOLEIL, L’Orme des Merisiers, St Aubin, BP 48, F-91192Gif sur Yvette, France
| | - Eric Rivière
- Institut
de Chimie Moléculaire et des Matériaux d’Orsay,
CNRS, Université Paris-Saclay, 91405Orsay, France
| | - Anne Bleuzen
- Institut
de Chimie Moléculaire et des Matériaux d’Orsay,
CNRS, Université Paris-Saclay, 91405Orsay, France
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19
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Bordage A, N’Diaye A, Bleuzen A. Prussian Blue analogs and transition metal K-edge XMCD: a longstanding friendship. CR CHIM 2022. [DOI: 10.5802/crchim.211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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20
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Ilin AM, van der Graaf CM, Yusta I, Sorrentino A, Sánchez-Andrea I, Sánchez-España J. Glycerol amendment enhances biosulfidogenesis in acid mine drainage-affected areas: An incubation column experiment. Front Bioeng Biotechnol 2022; 10:978728. [PMID: 36105607 PMCID: PMC9464833 DOI: 10.3389/fbioe.2022.978728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 08/02/2022] [Indexed: 11/30/2022] Open
Abstract
Microbial sulfate (SO42−) reduction in Acid Mine Drainage (AMD) environments can ameliorate the acidity and extreme metal concentrations by consumption of protons via the reduction of SO42− to hydrogen sulfide (H2S) and the concomitant precipitation of metals as metal sulfides. The activity of sulfate-reducing bacteria can be stimulated by the amendment of suitable organic carbon sources in these generally oligotrophic environments. Here, we used incubation columns (IC) as model systems to investigate the effect of glycerol amendment on the microbial community composition and its effect on the geochemistry of sediment and waters in AMD environments. The ICs were built with natural water and sediments from four distinct AMD-affected sites with different nutrient regimes: the oligotrophic Filón Centro and Guadiana acidic pit lakes, the Tintillo river (Huelva, Spain) and the eutrophic Brunita pit lake (Murcia, Spain). Physicochemical parameters were monitored during 18 months, and the microbial community composition was determined at the end of incubation through 16S rRNA gene amplicon sequencing. SEM-EDX analysis of sediments and suspended particulate matter was performed to investigate the microbially-induced mineral (neo)formation. Glycerol amendment strongly triggered biosulfidogenesis in all ICs, with pH increase and metal sulfide formation, but the effect was much more pronounced in the ICs from oligotrophic systems. Analysis of the microbial community composition at the end of the incubations showed that the SRB Desulfosporosinus was among the dominant taxa observed in all sulfidogenic columns, whereas the SRB Desulfurispora, Desulfovibrio and Acididesulfobacillus appeared to be more site-specific. Formation of Fe3+ and Al3+ (oxy)hydroxysulfates was observed during the initial phase of incubation together with increasing pH while formation of metal sulfides (predominantly, Zn, Fe and Cu sulfides) was observed after 1–5 months of incubation. Chemical analysis of the aqueous phase at the end of incubation showed almost complete removal of dissolved metals (Cu, Zn, Cd) in the amended ICs, while Fe and SO42− increased towards the water-sediment interface, likely as a result of the reductive dissolution of Fe(III) minerals enhanced by Fe-reducing bacteria. The combined geochemical and microbiological analyses further establish the link between biosulfidogenesis and natural attenuation through metal sulfide formation and proton consumption.
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Affiliation(s)
- A. M. Ilin
- Department of Geology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Barrio Sarriena s/n, Leioa, Spain
- *Correspondence: A. M. Ilin, ; J. Sánchez-España,
| | - C. M. van der Graaf
- Laboratory of Microbiology, Wageningen University (WUR), Wageningen, Netherlands
| | - I. Yusta
- Department of Geology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Barrio Sarriena s/n, Leioa, Spain
| | - A. Sorrentino
- ALBA Synchrotron Light Source, Cerdanyola del Vallés, Barcelona, Spain
| | - I. Sánchez-Andrea
- Laboratory of Microbiology, Wageningen University (WUR), Wageningen, Netherlands
| | - J. Sánchez-España
- Mine Wastes and Environmental Geochemistry Research Group, Department of Geological Resources for the Ecological Transition, (CN IGME-CSIC), Madrid, Spain
- *Correspondence: A. M. Ilin, ; J. Sánchez-España,
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21
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Usachov DY, Glazkova D, Tarasov AV, Schulz S, Poelchen G, Bokai KA, Vilkov OY, Dudin P, Kummer K, Kliemt K, Krellner C, Vyalikh DV. Estimating the Orientation of 4f Magnetic Moments by Classical Photoemission. J Phys Chem Lett 2022; 13:7861-7869. [PMID: 35977384 DOI: 10.1021/acs.jpclett.2c02203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
To use efficiently the magnetic functionalities emerging at the surfaces or interfaces of novel lanthanides-based materials, there is a need for complementary methods to probe the atomic-layer resolved magnetic properties. Here, we show that 4f photoelectron spectroscopy is highly sensitive to the collective orientation of 4f magnetic moments and, thus, a powerful tool for characterizing the related properties. To demonstrate this, we present the results of systematic study of a family of layered crystalline 4f-materials, which are crystallized in the body-centered tetragonal ThCr2Si2 structure. Analysis of 4f spectra indicates that the 4f moments at the surface experience a strong reorientation with respect to the bulk, caused by changes of the crystal-electric field. The presented database of the computed 4f spectra for all trivalent rare-earth ions in their different MJ states will facilitate the estimation of the orientation of the 4f magnetic moments in the layered 4f-systems for efficient control of their magnetic properties.
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Affiliation(s)
- Dmitry Yu Usachov
- St. Petersburg State University, 7/9 Universitetskaya nab, St. Petersburg 199034, Russia
| | - Daria Glazkova
- St. Petersburg State University, 7/9 Universitetskaya nab, St. Petersburg 199034, Russia
| | - Artem V Tarasov
- St. Petersburg State University, 7/9 Universitetskaya nab, St. Petersburg 199034, Russia
| | - Susanne Schulz
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, D-01062 Dresden, Germany
| | - Georg Poelchen
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, D-01062 Dresden, Germany
- European Synchrotron Radiation Facility (ESRF), 38043 Grenoble, France
| | - Kirill A Bokai
- St. Petersburg State University, 7/9 Universitetskaya nab, St. Petersburg 199034, Russia
| | - Oleg Yu Vilkov
- St. Petersburg State University, 7/9 Universitetskaya nab, St. Petersburg 199034, Russia
| | - Pavel Dudin
- Synchrotron-SOLEIL, Saint-Aubin, BP48, 91192 Gif-sur-Yvette, France
| | - Kurt Kummer
- European Synchrotron Radiation Facility (ESRF), 38043 Grenoble, France
| | - Kristin Kliemt
- Kristall-und Materiallabor, Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue Strasse 1, D-60438 Frankfurt am Main, Germany
| | - Cornelius Krellner
- Kristall-und Materiallabor, Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue Strasse 1, D-60438 Frankfurt am Main, Germany
| | - Denis V Vyalikh
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
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22
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Singh JP, Paidi AK, Chae KH, Lee S, Ahn D. Synchrotron radiation based X-ray techniques for analysis of cathodes in Li rechargeable batteries. RSC Adv 2022; 12:20360-20378. [PMID: 35919598 PMCID: PMC9277717 DOI: 10.1039/d2ra01250b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 06/15/2022] [Indexed: 01/21/2023] Open
Abstract
Li-ion rechargeable batteries are promising systems for large-scale energy storage solutions. Understanding the electrochemical process in the cathodes of these batteries using suitable techniques is one of the crucial steps for developing them as next-generation energy storage devices. Due to the broad energy range, synchrotron X-ray techniques provide a better option for characterizing the cathodes compared to the conventional laboratory-scale characterization instruments. This work gives an overview of various synchrotron radiation techniques for analyzing cathodes of Li-rechargeable batteries by depicting instrumental details of X-ray diffraction, X-ray absorption spectroscopy, X-ray imaging, and X-ray near-edge fine structure-imaging. Analysis and simulation procedures to get appropriate information of structural order, local electronic/atomic structure, chemical phase mapping and pores in cathodes are discussed by taking examples of various cathode materials. Applications of these synchrotron techniques are also explored to investigate oxidation state, metal-oxygen hybridization, quantitative local atomic structure, Ni oxidation phase and pore distribution in Ni-rich layered oxide cathodes.
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Affiliation(s)
- Jitendra Pal Singh
- Pohang Accelerator Laboratory, Pohang University of Science and Technology Pohang-37673 Republic of Korea
- Department of Physics, Manav Rachna University Faridabad-121004 Haryana India
| | - Anil Kumar Paidi
- Pohang Accelerator Laboratory, Pohang University of Science and Technology Pohang-37673 Republic of Korea
| | - Keun Hwa Chae
- Advanced Analysis Center, Korea Institute of Science and Technology Seoul-02792 Republic of Korea
| | - Sangsul Lee
- Pohang Accelerator Laboratory, Pohang University of Science and Technology Pohang-37673 Republic of Korea
- Xavisoptics Pohang-37673 Republic of Korea
| | - Docheon Ahn
- Pohang Accelerator Laboratory, Pohang University of Science and Technology Pohang-37673 Republic of Korea
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23
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Birch MT, Cortés-Ortuño D, Litzius K, Wintz S, Schulz F, Weigand M, Štefančič A, Mayoh DA, Balakrishnan G, Hatton PD, Schütz G. Toggle-like current-induced Bloch point dynamics of 3D skyrmion strings in a room temperature nanowire. Nat Commun 2022; 13:3630. [PMID: 35750676 PMCID: PMC9232487 DOI: 10.1038/s41467-022-31335-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 06/15/2022] [Indexed: 11/09/2022] Open
Abstract
Research into practical applications of magnetic skyrmions, nanoscale solitons with interesting topological and transport properties, has traditionally focused on two dimensional (2D) thin-film systems. However, the recent observation of novel three dimensional (3D) skyrmion-like structures, such as hopfions, skyrmion strings (SkS), skyrmion bundles, and skyrmion braids, motivates the investigation of new designs, aiming to exploit the third spatial dimension for more compact and higher performance spintronic devices in 3D or curvilinear geometries. A crucial requirement of such device schemes is the control of the 3D magnetic structures via charge or spin currents, which has yet to be experimentally observed. In this work, we utilise real-space imaging to investigate the dynamics of a 3D SkS within a nanowire of Co8Zn9Mn3 at room temperature. Utilising single current pulses, we demonstrate current-induced nucleation of a single SkS, and a toggle-like positional switching of an individual Bloch point at the end of a SkS. The observations highlight the possibility to locally manipulate 3D topological spin textures, opening up a range of design concepts for future 3D spintronic devices. In three dimensional systems with broken bulk inversion symmetry, skyrmions can form extended string-like structures. Here, Birch et al use scanning transmission x-ray microscopy to demonstrate the current induced generation and motion of these three dimensional skyrmion strings.
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Affiliation(s)
- M T Birch
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany.
| | - D Cortés-Ortuño
- Department of Earth Sciences, Utrecht University, 3584, CB, Utrecht, The Netherlands.
| | - K Litzius
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - S Wintz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany.,Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489, Berlin, Germany
| | - F Schulz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - M Weigand
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489, Berlin, Germany
| | - A Štefančič
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK.,Electrochemistry Laboratory, Paul Scherrer Institut, CH-5232, Villigen, PSI, Switzerland
| | - D A Mayoh
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - G Balakrishnan
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - P D Hatton
- Department of Physics, Durham University, Durham, DH1 3LE, UK
| | - G Schütz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
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24
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Birch MT, Cortés-Ortuño D, Litzius K, Wintz S, Schulz F, Weigand M, Štefančič A, Mayoh DA, Balakrishnan G, Hatton PD, Schütz G. Toggle-like current-induced Bloch point dynamics of 3D skyrmion strings in a room temperature nanowire. Nat Commun 2022; 13:3630. [PMID: 35750676 DOI: 10.21203/rs.3.rs-1235546/v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 06/15/2022] [Indexed: 05/23/2023] Open
Abstract
Research into practical applications of magnetic skyrmions, nanoscale solitons with interesting topological and transport properties, has traditionally focused on two dimensional (2D) thin-film systems. However, the recent observation of novel three dimensional (3D) skyrmion-like structures, such as hopfions, skyrmion strings (SkS), skyrmion bundles, and skyrmion braids, motivates the investigation of new designs, aiming to exploit the third spatial dimension for more compact and higher performance spintronic devices in 3D or curvilinear geometries. A crucial requirement of such device schemes is the control of the 3D magnetic structures via charge or spin currents, which has yet to be experimentally observed. In this work, we utilise real-space imaging to investigate the dynamics of a 3D SkS within a nanowire of Co8Zn9Mn3 at room temperature. Utilising single current pulses, we demonstrate current-induced nucleation of a single SkS, and a toggle-like positional switching of an individual Bloch point at the end of a SkS. The observations highlight the possibility to locally manipulate 3D topological spin textures, opening up a range of design concepts for future 3D spintronic devices.
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Affiliation(s)
- M T Birch
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany.
| | - D Cortés-Ortuño
- Department of Earth Sciences, Utrecht University, 3584, CB, Utrecht, The Netherlands.
| | - K Litzius
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - S Wintz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489, Berlin, Germany
| | - F Schulz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - M Weigand
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489, Berlin, Germany
| | - A Štefančič
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
- Electrochemistry Laboratory, Paul Scherrer Institut, CH-5232, Villigen, PSI, Switzerland
| | - D A Mayoh
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - G Balakrishnan
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - P D Hatton
- Department of Physics, Durham University, Durham, DH1 3LE, UK
| | - G Schütz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
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25
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Xu Z, Romankov V, Doll A, Dreiser J. Orienting dilute thin films of non-planar spin-1/2 vanadyl-phthalocyanine complexes. MATERIALS ADVANCES 2022; 3:4938-4946. [PMID: 35812836 PMCID: PMC9207598 DOI: 10.1039/d2ma00157h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
The molecular orientation as well as the electronic and magnetic properties of vanadyl-phthalocyanine (VOPc) diluted into titanyl-phthalocyanine (TiOPc) thin films on Si(100) and polycrystalline aluminum substrates have been investigated by soft X-ray absorption spectroscopy (XAS), X-ray linear dichroism (XLD) and X-ray magnetic circular dichroism (XMCD). On the bare substrates the films grow with a standing-up geometry. By contrast, on template layers of 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA), they assume a lying-down orientation. Moreover, a theoretical model based on the normalized intensity of the nitrogen K-edge XLD is established in order to extract the molecular orientation angle quantitatively without the need for crystallinity and with the sub-monolayer sensitivity of soft-XAS. XMCD reveals that the vanadium magnetic properties are preserved in both non-diluted and diluted films. The results pave the way toward the use of VOPc as nanometer-sized spin quantum bits.
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Affiliation(s)
- Zhewen Xu
- Swiss Light Source, Paul Scherrer Institut Forschungsstrasse 111 CH-5232 Villigen PSI Switzerland
| | - Vladyslav Romankov
- Swiss Light Source, Paul Scherrer Institut Forschungsstrasse 111 CH-5232 Villigen PSI Switzerland
| | - Andrin Doll
- Swiss Light Source, Paul Scherrer Institut Forschungsstrasse 111 CH-5232 Villigen PSI Switzerland
| | - Jan Dreiser
- Swiss Light Source, Paul Scherrer Institut Forschungsstrasse 111 CH-5232 Villigen PSI Switzerland
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26
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Birch MT, Powalla L, Wintz S, Hovorka O, Litzius K, Loudon JC, Turnbull LA, Nehruji V, Son K, Bubeck C, Rauch TG, Weigand M, Goering E, Burghard M, Schütz G. History-dependent domain and skyrmion formation in 2D van der Waals magnet Fe 3GeTe 2. Nat Commun 2022; 13:3035. [PMID: 35641499 PMCID: PMC9156682 DOI: 10.1038/s41467-022-30740-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 05/16/2022] [Indexed: 11/16/2022] Open
Abstract
The discovery of two-dimensional magnets has initiated a new field of research, exploring both fundamental low-dimensional magnetism, and prospective spintronic applications. Recently, observations of magnetic skyrmions in the 2D ferromagnet Fe3GeTe2 (FGT) have been reported, introducing further application possibilities. However, controlling the exhibited magnetic state requires systematic knowledge of the history-dependence of the spin textures, which remains largely unexplored in 2D magnets. In this work, we utilise real-space imaging, and complementary simulations, to determine and explain the thickness-dependent magnetic phase diagrams of an exfoliated FGT flake, revealing a complex, history-dependent emergence of the uniformly magnetised, stripe domain and skyrmion states. The results show that the interplay of the dominant dipolar interaction and strongly temperature dependent out-of-plane anisotropy energy terms enables the selective stabilisation of all three states at zero field, and at a single temperature, while the Dzyaloshinksii-Moriya interaction must be present to realise the observed Néel-type domain walls. The findings open perspectives for 2D devices incorporating topological spin textures. Fe3GeTe2, known as FGT, is a van der Waals magnetic material that was recently shown to host magnetic skyrmions. Here, Birch et al using both X-ray and electron microscopy to study the stability of skyrmions in FGT, revealing how the sample history can influence skyrmion formation
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Affiliation(s)
- M T Birch
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany.
| | - L Powalla
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany.
| | - S Wintz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - O Hovorka
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - K Litzius
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - J C Loudon
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK
| | - L A Turnbull
- Department of Physics, Durham University, Durham, DH1 3LE, UK
| | - V Nehruji
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - K Son
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany.,Department of Physics Education, Kongju National University, Gongju, 32588, South Korea
| | - C Bubeck
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - T G Rauch
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institut Nanospektroskopie, 12489, Berlin, Germany
| | - M Weigand
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institut Nanospektroskopie, 12489, Berlin, Germany
| | - E Goering
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - M Burghard
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
| | - G Schütz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
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27
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Marcano L, Orue I, Gandia D, Gandarias L, Weigand M, Abrudan RM, García-Prieto A, García-Arribas A, Muela A, Fdez-Gubieda ML, Valencia S. Magnetic Anisotropy of Individual Nanomagnets Embedded in Biological Systems Determined by Axi-asymmetric X-ray Transmission Microscopy. ACS NANO 2022; 16:7398-7408. [PMID: 35472296 PMCID: PMC9878725 DOI: 10.1021/acsnano.1c09559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Over the past few years, the use of nanomagnets in biomedical applications has increased. Among others, magnetic nanostructures can be used as diagnostic and therapeutic agents in cardiovascular diseases, to locally destroy cancer cells, to deliver drugs at specific positions, and to guide (and track) stem cells to damaged body locations in regenerative medicine and tissue engineering. All these applications rely on the magnetic properties of the nanomagnets which are mostly determined by their magnetic anisotropy. Despite its importance, the magnetic anisotropy of the individual magnetic nanostructures is unknown. Currently available magnetic sensitive microscopic methods are either limited in spatial resolution or in magnetic field strength or, more relevant, do not allow one to measure magnetic signals of nanomagnets embedded in biological systems. Hence, the use of nanomagnets in biomedical applications must rely on mean values obtained after averaging samples containing thousands of dissimilar entities. Here we present a hybrid experimental/theoretical method capable of working out the magnetic anisotropy constant and the magnetic easy axis of individual magnetic nanostructures embedded in biological systems. The method combines scanning transmission X-ray microscopy using an axi-asymmetric magnetic field with theoretical simulations based on the Stoner-Wohlfarth model. The validity of the method is demonstrated by determining the magnetic anisotropy constant and magnetic easy axis direction of 15 intracellular magnetite nanoparticles (50 nm in size) biosynthesized inside a magnetotactic bacterium.
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Affiliation(s)
- Lourdes Marcano
- Helmholtz-Zentrum
Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
- Dpto.
Electricidad y Electrónica, Universidad
del País Vasco - UPV/EHU, 48940 Leioa, Spain
| | - Iñaki Orue
- SGIker, Universidad del País Vasco - UPV/EHU, 48940 Leioa, Spain
| | - David Gandia
- BCMaterials, Bld. Martina Casiano third floor, 48940 Leioa, Spain
| | - Lucía Gandarias
- Dpto.
Inmunología, Microbiología y Parasitología, Universidad del País Vasco - UPV/EHU, 48940 Leioa, Spain
| | - Markus Weigand
- Helmholtz-Zentrum
Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - Radu Marius Abrudan
- Helmholtz-Zentrum
Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - Ana García-Prieto
- Dpto. Física
Aplicada, Universidad del País Vasco - UPV/EHU, 48013 Bilbao, Spain
| | - Alfredo García-Arribas
- Dpto.
Electricidad y Electrónica, Universidad
del País Vasco - UPV/EHU, 48940 Leioa, Spain
- BCMaterials, Bld. Martina Casiano third floor, 48940 Leioa, Spain
| | - Alicia Muela
- Dpto.
Inmunología, Microbiología y Parasitología, Universidad del País Vasco - UPV/EHU, 48940 Leioa, Spain
| | - M. Luisa Fdez-Gubieda
- Dpto.
Electricidad y Electrónica, Universidad
del País Vasco - UPV/EHU, 48940 Leioa, Spain
- BCMaterials, Bld. Martina Casiano third floor, 48940 Leioa, Spain
| | - Sergio Valencia
- Helmholtz-Zentrum
Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
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28
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N'Diaye A, Bordage A, Nataf L, Baudelet F, Rivière E, Bleuzen A. Toward Quantitative Magnetic Information from Transition Metal K-Edge XMCD of Prussian Blue Analogs. Inorg Chem 2022; 61:6326-6336. [PMID: 35414167 DOI: 10.1021/acs.inorgchem.2c00637] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two series of Prussian blue analogs (PBA) were used as model compounds in order to disentangle the information contained in X-ray magnetic circular dichroism (XMCD) at the K-edges of transition metals. The number of 3d electrons on one site of the bimetallic cyanide polymer has been varied by associating to the [Fe(CN)6]3- or the [Cr(CN)6]3- precursors various divalent metal ions A2+ (Mn2+, Fe2+, Co2+, Ni2+, and Cu2+). The compounds were studied by X-ray diffraction and SQUID magnetometry, as well as by X-ray absorption spectroscopy and XMCD at the K-edges of the A2+ transition metal ion. The study shows that the 1s → 4p contribution to the A K-edge XMCD signal can be related to the electronic structure and the magnetic behavior of the probed A2+ ion: the shape of the signal to the filling of the 3d orbitals, the sign of the signal to the direction of the magnetic moment with respect to the applied magnetic field, the intensity of the signal to the total spin number SA, and the area under curve to the Curie constant CA. The whole study hence demonstrates that PBAs are particularly well-adapted for understanding the information contained in the transition metals K-edge XMCD signals. It also offers new perspectives toward the full disentangling of the information contained in these signals and access to new insights into materials magnetic properties.
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Affiliation(s)
- Adama N'Diaye
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - Amélie Bordage
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - Lucie Nataf
- Synchrotron SOLEIL, L'Orme des Merisiers, St. Aubin, BP 48, F-91192 Gif sur Yvette, France
| | - François Baudelet
- Synchrotron SOLEIL, L'Orme des Merisiers, St. Aubin, BP 48, F-91192 Gif sur Yvette, France
| | - Eric Rivière
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - Anne Bleuzen
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris-Saclay, 91405 Orsay, France
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29
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Abstract
Magnetic force microscopy (MFM) enables to characterize magnetic properties with submicron (nanoscale) resolution and without much demand on sample surface preparation. MFM can operate in a wide range of temperatures and environmental conditions, that is, vacuum, liquid, or air, therefore this technique has already become the most common tool used to characterize variety of magnetic materials ranging from ferromagnetic thin films and 2D materials to biomedical and/or biological materials. The purpose of this review is to provide a summary of MFM basic fundamentals in the frame of other related methods and, correspondingly, a brief overview of physics and chiefly biomedical as well as biological applications of MFM.
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30
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Song D, Zheng F, Dunin-Borkowski RE. Prospect for measuring two-dimensional van der Waals magnets by electron magnetic chiral dichroism. Ultramicroscopy 2022; 234:113476. [PMID: 35114564 DOI: 10.1016/j.ultramic.2022.113476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/13/2022] [Accepted: 01/24/2022] [Indexed: 10/19/2022]
Abstract
Two-dimensional (2D) van der Waals magnets have drawn considerable attention in recent years triggered by the huge interest in novel magnetism and spintronic devices. Magnetic measurement of 2D van der Waals (vdW) magnets is crucial to understand the physical origin of magnetism in 2D limits. Therefore, advanced magnetic characterization techniques are highly required. However, only a limited number of such techniques are available due to the extremely small volume of 2D vdW magnets. Here, we introduce the electron magnetic chiral dichroism (EMCD) technique in transmission electron microscope (TEM) to measure 2D vdW crystals. In comparison with some other already-employed techniques in 2D magnets, EMCD is able to quantitatively measure magnetic parameters in three orthogonal directions at nanometer or even at atomic scale. We then perform EMCD simulations on several typical 2D vdW magnets with respect to the accelerating voltage, the number of atomic layers and beam tilt under zone axial orientation. The intensity and distribution of EMCD signals in three orthogonal directions are given in the diffraction plane, thereby providing an optimized design to achieve EMCD measurements. Finally, we discuss the signal-to-noise-ratio and required electron dose in order to obtain a measurable EMCD signal for 2D vdW magnets. Our results provide a feasibility analysis and guideline to measure 2D vdW magnets in future experiments.
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Affiliation(s)
- Dongsheng Song
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China; Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich 52425, Germany.
| | - Fengshan Zheng
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich 52425, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich 52425, Germany
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31
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Kumar TSJ, Arumugam M. Optical Properties of Magnetic Nanoalloys and Nanocomposites. HANDBOOK OF MAGNETIC HYBRID NANOALLOYS AND THEIR NANOCOMPOSITES 2022:547-573. [DOI: 10.1007/978-3-030-90948-2_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
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32
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Kumar TSJ, Arumugam M. Optical Properties of Magnetic Nanoalloys and Nanocomposites. HANDBOOK OF MAGNETIC HYBRID NANOALLOYS AND THEIR NANOCOMPOSITES 2022:1-27. [DOI: 10.1007/978-3-030-34007-0_18-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 02/25/2022] [Indexed: 06/16/2023]
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33
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Shaw JM, Knut R, Armstrong A, Bhandary S, Kvashnin Y, Thonig D, Delczeg-Czirjak EK, Karis O, Silva TJ, Weschke E, Nembach HT, Eriksson O, Arena DA. Quantifying Spin-Mixed States in Ferromagnets. PHYSICAL REVIEW LETTERS 2021; 127:207201. [PMID: 34860034 DOI: 10.1103/physrevlett.127.207201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 09/08/2021] [Indexed: 06/13/2023]
Abstract
We quantify the presence of spin-mixed states in ferromagnetic 3D transition metals by precise measurement of the orbital moment. While central to phenomena such as Elliot-Yafet scattering, quantification of the spin-mixing parameter has hitherto been confined to theoretical calculations. We demonstrate that this information is also available by experimental means. Comparison of ferromagnetic resonance spectroscopy with x-ray magnetic circular dichroism results show that Kittel's original derivation of the spectroscopic g factor requires modification, to include spin mixing of valence band states. Our results are supported by ab initio relativistic electronic structure theory.
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Affiliation(s)
- Justin M Shaw
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Ronny Knut
- Department of Physics and Astronomy, University Uppsala, S-75120 Uppsala, Sweden
| | - Abigail Armstrong
- Department of Physics, University of South Florida, Tampa, Florida 33620, USA
| | - Sumanta Bhandary
- School of Physics and CRANN Institute, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
| | - Yaroslav Kvashnin
- Department of Physics and Astronomy, University Uppsala, S-75120 Uppsala, Sweden
| | - Danny Thonig
- School of Science and Technology, Örebro University, SE-701 82 Örebro, Sweden
| | | | - Olof Karis
- Department of Physics and Astronomy, University Uppsala, S-75120 Uppsala, Sweden
| | - T J Silva
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Eugen Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, D-12489 Berlin, Germany
| | - Hans T Nembach
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado 80305, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Olle Eriksson
- Department of Physics and Astronomy, University Uppsala, S-75120 Uppsala, Sweden
- School of Science and Technology, Örebro University, SE-701 82 Örebro, Sweden
| | - Dario A Arena
- Department of Physics, University of South Florida, Tampa, Florida 33620, USA
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Novikov VV, Nelyubina YV. Modern physical methods for the molecular design of single-molecule magnets. RUSSIAN CHEMICAL REVIEWS 2021. [DOI: 10.1070/rcr5002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Abstract
Many paramagnetic metal complexes have emerged as unique magnetic materials (single-molecule magnets), which behave as conventional magnets at the single-molecule level, thereby making it possible to use them in modern devices for data storage and processing. The rational design of these complexes, however, requires a deep understanding of the physical laws behind a single-molecule magnet behaviour, the mechanisms of magnetic relaxation that determines the magnetic properties and the relationship of these properties with the structure of single-molecule magnets. This review focuses on the physical methods providing such understanding, including different versions and various combinations of magnetometry, electron paramagnetic and nuclear magnetic resonance spectroscopy, optical spectroscopy and X-ray diffraction. Many of these methods are traditionally used to determine the composition and structure of new chemical compounds. However, they are rarely applied to study molecular magnetism.
The bibliography includes 224 references.
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35
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Liu J, Hesjedal T. Magnetic Topological Insulator Heterostructures: A Review. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021:e2102427. [PMID: 34665482 DOI: 10.1002/adma.202102427] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/05/2021] [Indexed: 06/13/2023]
Abstract
Topological insulators (TIs) provide intriguing prospects for the future of spintronics due to their large spin-orbit coupling and dissipationless, counter-propagating conduction channels in the surface state. The combination of topological properties and magnetic order can lead to new quantum states including the quantum anomalous Hall effect that was first experimentally realized in Cr-doped (Bi,Sb)2 Te3 films. Since magnetic doping can introduce detrimental effects, requiring very low operational temperatures, alternative approaches are explored. Proximity coupling to magnetically ordered systems is an obvious option, with the prospect to raise the temperature for observing the various quantum effects. Here, an overview of proximity coupling and interfacial effects in TI heterostructures is presented, which provides a versatile materials platform for tuning the magnetic and topological properties of these exciting materials. An introduction is first given to the heterostructure growth by molecular beam epitaxy and suitable structural, electronic, and magnetic characterization techniques. Going beyond transition-metal-doped and undoped TI heterostructures, examples of heterostructures are discussed, including rare-earth-doped TIs, magnetic insulators, and antiferromagnets, which lead to exotic phenomena such as skyrmions and exchange bias. Finally, an outlook on novel heterostructures such as intrinsic magnetic TIs and systems including 2D materials is given.
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Affiliation(s)
- Jieyi Liu
- Clarendon Laboratory, Department of Physics University of Oxford, Parks Road, Oxford, OX1 3PU, UK
| | - Thorsten Hesjedal
- Clarendon Laboratory, Department of Physics University of Oxford, Parks Road, Oxford, OX1 3PU, UK
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36
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Paschke F, Birk T, Enenkel V, Liu F, Romankov V, Dreiser J, Popov AA, Fonin M. Exceptionally High Blocking Temperature of 17 K in a Surface-Supported Molecular Magnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2102844. [PMID: 34396601 DOI: 10.1002/adma.202102844] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/09/2021] [Indexed: 06/13/2023]
Abstract
Single-molecule magnets (SMMs) are among the most promising building blocks for future magnetic data storage or quantum computing applications, owing to magnetic bistability and long magnetic relaxation times. The practical device integration requires realization of 2D surface assemblies of SMMs, where each magnetic unit shows magnetic relaxation being sufficiently slow at application-relevant temperatures. Using X-ray absorption spectroscopy and X-ray magnetic circular dichroism, it is shown that sub-monolayers of Dy2 @C80 (CH2 Ph) dimetallofullerenes prepared on graphene by electrospray deposition exhibit magnetic behavior fully comparable to that of the bulk. Magnetic hysteresis and relaxation time measurements show that the magnetic moment remains stable for 100 s at 17 K, marking the blocking temperature TB(100) , being not only in excellent agreement with that of the bulk sample but also representing by far the highest one detected for a surface-supported single-molecule magnet. The reported findings give a boost to the efforts to stabilize and address the spin degree of freedom in molecular magnets aiming at the realization of SMM-based spintronic units.
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Affiliation(s)
- Fabian Paschke
- Department of Physics, University of Konstanz, 78457, Konstanz, Germany
| | - Tobias Birk
- Department of Physics, University of Konstanz, 78457, Konstanz, Germany
| | - Vivien Enenkel
- Department of Physics, University of Konstanz, 78457, Konstanz, Germany
| | - Fupin Liu
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), 01069, Dresden, Germany
| | - Vladyslav Romankov
- Swiss Light Source, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Jan Dreiser
- Swiss Light Source, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Alexey A Popov
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), 01069, Dresden, Germany
| | - Mikhail Fonin
- Department of Physics, University of Konstanz, 78457, Konstanz, Germany
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Dmitriyeva A, Mikheev V, Zarubin S, Chouprik A, Vinai G, Polewczyk V, Torelli P, Matveyev Y, Schlueter C, Karateev I, Yang Q, Chen Z, Tao L, Tsymbal EY, Zenkevich A. Magnetoelectric Coupling at the Ni/Hf 0.5Zr 0.5O 2 Interface. ACS NANO 2021; 15:14891-14902. [PMID: 34468129 DOI: 10.1021/acsnano.1c05001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Composite multiferroics containing ferroelectric and ferromagnetic components often have much larger magnetoelectric coupling compared to their single-phase counterparts. Doped or alloyed HfO2-based ferroelectrics may serve as a promising component in composite multiferroic structures potentially feasible for technological applications. Recently, a strong charge-mediated magnetoelectric coupling at the Ni/HfO2 interface has been predicted using density functional theory calculations. Here, we report on the experimental evidence of such magnetoelectric coupling at the Ni/Hf0.5Zr0.5O2(HZO) interface. Using a combination of operando XAS/XMCD and HAXPES/MCDAD techniques, we probe element-selectively the local magnetic properties at the Ni/HZO interface in functional Au/Co/Ni/HZO/W capacitors and demonstrate clear evidence of the ferroelectric polarization effect on the magnetic response of a nanometer-thick Ni marker layer. The observed magnetoelectric effect and the electronic band lineup of the Ni/HZO interface are interpreted based on the results of our theoretical modeling. It elucidates the critical role of an ultrathin NiO interlayer, which controls the sign of the magnetoelectric effect as well as provides a realistic band offset at the Ni/HZO interface, in agreement with the experiment. Our results hold promise for the use of ferroelectric HfO2-based composite multiferroics for the design of multifunctional devices compatible with modern semiconductor technology.
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Affiliation(s)
- Anna Dmitriyeva
- Moscow Institute of Physics and Technology, 9, Institutskiy lane, Dolgoprudny, Moscow Region, 141700, Russia
| | - Vitalii Mikheev
- Moscow Institute of Physics and Technology, 9, Institutskiy lane, Dolgoprudny, Moscow Region, 141700, Russia
| | - Sergei Zarubin
- Moscow Institute of Physics and Technology, 9, Institutskiy lane, Dolgoprudny, Moscow Region, 141700, Russia
| | - Anastasia Chouprik
- Moscow Institute of Physics and Technology, 9, Institutskiy lane, Dolgoprudny, Moscow Region, 141700, Russia
| | - Giovanni Vinai
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S. 14 km 163.5, Trieste I-34149, Italy
| | - Vincent Polewczyk
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S. 14 km 163.5, Trieste I-34149, Italy
| | - Piero Torelli
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S. 14 km 163.5, Trieste I-34149, Italy
| | - Yury Matveyev
- Deutsches Elektronen-Synchrotron, 85 Notkestraße, Hamburg, D-22607, Germany
| | | | - Igor Karateev
- National Research Center "Kurchatov Institute", Moscow, 123182, Russia
| | - Qiong Yang
- School of Materials Science and Engineering, Xiangtan University, Xiangtan, Hunan 411105, China
| | - Zhaojin Chen
- School of Materials Science and Engineering, Xiangtan University, Xiangtan, Hunan 411105, China
| | - Lingling Tao
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Evgeny Y Tsymbal
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Andrei Zenkevich
- Moscow Institute of Physics and Technology, 9, Institutskiy lane, Dolgoprudny, Moscow Region, 141700, Russia
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Kimata M, Sasabe N, Kurita K, Yamasaki Y, Tabata C, Yokoyama Y, Kotani Y, Ikhlas M, Tomita T, Amemiya K, Nojiri H, Nakatsuji S, Koretsune T, Nakao H, Arima TH, Nakamura T. X-ray study of ferroic octupole order producing anomalous Hall effect. Nat Commun 2021; 12:5582. [PMID: 34552070 PMCID: PMC8458343 DOI: 10.1038/s41467-021-25834-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 08/29/2021] [Indexed: 11/21/2022] Open
Abstract
Recently found anomalous Hall, Nernst, magnetooptical Kerr, and spin Hall effects in the antiferromagnets Mn3X (X = Sn, Ge) are attracting much attention for spintronics and energy harvesting. Since these materials are antiferromagnets, the origin of these functionalities is expected to be different from that of conventional ferromagnets. Here, we report the observation of ferroic order of magnetic octupole in Mn3Sn by X-ray magnetic circular dichroism, which is only predicted theoretically so far. The observed signals are clearly decoupled with the behaviors of uniform magnetization, indicating that the present X-ray magnetic circular dichroism is not arising from the conventional magnetization. We have found that the appearance of this anomalous signal coincides with the time reversal symmetry broken cluster magnetic octupole order. Our study demonstrates that the exotic material functionalities are closely related to the multipole order, which can produce unconventional cross correlation functionalities.
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Affiliation(s)
- Motoi Kimata
- Institute for Materials Research, Tohoku University, Sendai, Miyagi, 980-8577, Japan.
| | - Norimasa Sasabe
- Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo, 679-5198, Japan
| | - Kensuke Kurita
- Department of Physics, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Yuichi Yamasaki
- Research and Services Division of Materials Data and Integrated System (MaDIS), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki, 305-0044, Japan
- Center for Emergent Matter Science (CEMS), RIKEN, Wako, 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Tokyo, 102-0076, Japan
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan
| | - Chihiro Tabata
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Osaka, 590-0494, Japan
| | - Yuichi Yokoyama
- Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo, 679-5198, Japan
| | - Yoshinori Kotani
- Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo, 679-5198, Japan
| | - Muhammad Ikhlas
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Takahiro Tomita
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Kenta Amemiya
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan
| | - Hiroyuki Nojiri
- Institute for Materials Research, Tohoku University, Sendai, Miyagi, 980-8577, Japan
| | - Satoru Nakatsuji
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
- Department of Physics, University of Tokyo, Hongo, Tokyo, 113-0033, Japan
- The Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA
- Trans-scale Quantum Science Institute, University of Tokyo, Hongo, Tokyo, 113-8654, Japan
| | - Takashi Koretsune
- Department of Physics, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Hironori Nakao
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan
| | - Taka-Hisa Arima
- Center for Emergent Matter Science (CEMS), RIKEN, Wako, 351-0198, Japan
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, 277-8561, Japan
| | - Tetsuya Nakamura
- Institute for Materials Research, Tohoku University, Sendai, Miyagi, 980-8577, Japan
- Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo, 679-5198, Japan
- International Center for Synchrotron Radiation Innovation Smart, Tohoku University, Sendai, Miyagi, 980-8577, Japan
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39
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Bai T, Ai J, Ma J, Duan Y, Han L, Jiang J, Che S. Resistance‐Chiral Anisotropy of Chiral Mesostructured Half‐metallic Fe
3
O
4
Films. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Te Bai
- School of Chemistry and Chemical Engineering State Key Laboratory of Metal Matrix Composites Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 P. R. China
| | - Jing Ai
- School of Chemical Science and Engineering Tongji University 1239 Siping Road Shanghai 200092 P. R. China
| | - Jie Ma
- School of Physics and Astronomy Key Laboratory of Artificial Structures and Quantum Control Ministry of Education Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 P. R. China
| | - Yingying Duan
- School of Chemical Science and Engineering Tongji University 1239 Siping Road Shanghai 200092 P. R. China
| | - Lu Han
- School of Chemical Science and Engineering Tongji University 1239 Siping Road Shanghai 200092 P. R. China
| | - Jingang Jiang
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes School of Chemistry and Molecular Engineering East China Normal University 3663 North Zhongshan Road Shanghai 200062 P. R. China
| | - Shunai Che
- School of Chemistry and Chemical Engineering State Key Laboratory of Metal Matrix Composites Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 P. R. China
- School of Chemical Science and Engineering Tongji University 1239 Siping Road Shanghai 200092 P. R. China
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40
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Bai T, Ai J, Ma J, Duan Y, Han L, Jiang J, Che S. Resistance-Chiral Anisotropy of Chiral Mesostructured Half-metallic Fe 3 O 4 Films. Angew Chem Int Ed Engl 2021; 60:20036-20041. [PMID: 34224198 DOI: 10.1002/anie.202108142] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Indexed: 11/11/2022]
Abstract
Half-metallic materials are theoretically predicted to be metallic and insulating, which have not been confirmed experimentally, and the predictions are still in doubt. We report the resistance-chiral anisotropy (R-ChA), i.e., chirality-dependent electrical conductivity, in chiral mesostructured Fe3 O4 films (CMFFs) grown on the substrates via a hydrothermal method using amino acids as symmetry-breaking agents. Two levels of chirality exist in the CMFFs: primary distortion of the crystal lattice forms twisted nanoflakes, and secondary helical stacking of nanoflakes forms fan-shaped nanoplates. At temperatures below 30 K, the CMFFs exhibited metallic conductivity and insulation for one handedness and the other, respectively. The chirality-dependent effective magnetic fields were speculated to stabilize the opposite spin in the antipodal chiral frame, which led to the free transport of electrons in one handedness of the chiral structure and immobility for the other handedness.
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Affiliation(s)
- Te Bai
- School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, P. R. China
| | - Jing Ai
- School of Chemical Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, P. R. China
| | - Jie Ma
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control, Ministry of Education, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, P. R. China
| | - Yingying Duan
- School of Chemical Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, P. R. China
| | - Lu Han
- School of Chemical Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, P. R. China
| | - Jingang Jiang
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 3663 North Zhongshan Road, Shanghai, 200062, P. R. China
| | - Shunai Che
- School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, P. R. China.,School of Chemical Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, P. R. China
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41
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N'Diaye A, Bordage A, Nataf L, Baudelet F, Moreno T, Bleuzen A. A cookbook for the investigation of coordination polymers by transition metal K-edge XMCD. JOURNAL OF SYNCHROTRON RADIATION 2021; 28:1127-1136. [PMID: 34212876 DOI: 10.1107/s1600577521004884] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 05/08/2021] [Indexed: 06/13/2023]
Abstract
In order to disentangle the physical effects at the origin of transition metal K-edge X-ray magnetic circular dichroism (XMCD) in coordination polymers and quantify small structural distortions from the intensity of these signals, a systematic investigation of Prussian blue analogs as model compounds is being conducted. Here the effects of the temperature and of the external magnetic field are tackled; none of these external parameters modify the shape of the XMCD signal but they both critically modify its intensity. The optimized experimental conditions, as well as a reliable and robust normalization procedure, could thus be determined for the study of the intrinsic parameters. Through an extended discussion on measurements on other XMCD-dedicated beamlines and for other coordination compounds, we finally provide new transition metal K-edge XMCD users with useful information to initiate and successfully carry out their projects.
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Affiliation(s)
- Adama N'Diaye
- ICMMO, Université Paris Saclay, CNRS, 15 rue Georges Clémenceau, 91405 Orsay, France
| | - Amélie Bordage
- ICMMO, Université Paris Saclay, CNRS, 15 rue Georges Clémenceau, 91405 Orsay, France
| | - Lucie Nataf
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - François Baudelet
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Thierry Moreno
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Anne Bleuzen
- ICMMO, Université Paris Saclay, CNRS, 15 rue Georges Clémenceau, 91405 Orsay, France
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42
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Turnbull LA, Birch MT, Laurenson A, Bukin N, Burgos-Parra EO, Popescu H, Wilson MN, Stefančič A, Balakrishnan G, Ogrin FY, Hatton PD. Tilted X-Ray Holography of Magnetic Bubbles in MnNiGa Lamellae. ACS NANO 2021; 15:387-395. [PMID: 33119252 DOI: 10.1021/acsnano.0c07392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Nanoscopic lamellae of centrosymmetric ferromagnetic alloys have recently been reported to host the biskyrmion spin texture; however, this has been disputed as the misidentication of topologically trivial type-II magnetic bubbles. Here we demonstrate resonant soft X-ray holographic imaging of topological magnetic states in lamellae of the centrosymmetric alloy (Mn1-xNix)0.65Ga0.35 (x = 0.5), showing the presence of magnetic stripes evolving into single core magnetic bubbles. We observe rotation of the stripe phase via the nucleation and destruction of disclination defects. This indicates the system behaves as a conventional uniaxial ferromagnet. By utilizing the holography with extended reference by autocorrelation linear differential operator (HERALDO) method, we show tilted holographic images at 30° incidence confirming the presence of type-II magnetic bubbles in this system. This study demonstrates the utility of X-ray imaging techniques in identifying the topology of localized structures in nanoscale magnetism.
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Affiliation(s)
- Luke A Turnbull
- Centre for Materials Physics, Durham University, Durham, DH1 3LE United Kingdom
| | - Max T Birch
- Centre for Materials Physics, Durham University, Durham, DH1 3LE United Kingdom
- Diamond Light Source, Didcot, OX11 0DE United Kingdom
| | - Angus Laurenson
- School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL United Kingdom
| | - Nick Bukin
- School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL United Kingdom
| | | | - Horia Popescu
- Synchrotron SOLEIL, Saint Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Murray N Wilson
- Centre for Materials Physics, Durham University, Durham, DH1 3LE United Kingdom
| | - Aleš Stefančič
- Department of Physics, University of Warwick, Coventry, CV4 7AL United Kingdom
| | - Geetha Balakrishnan
- Department of Physics, University of Warwick, Coventry, CV4 7AL United Kingdom
| | - Feodor Y Ogrin
- School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL United Kingdom
| | - Peter D Hatton
- Centre for Materials Physics, Durham University, Durham, DH1 3LE United Kingdom
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43
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Avvisati G, Gargiani P, Mariani C, Betti MG. Tuning the Magnetic Coupling of a Molecular Spin Interface via Electron Doping. NANO LETTERS 2021; 21:666-672. [PMID: 33356332 DOI: 10.1021/acs.nanolett.0c04256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Mastering the magnetic response of molecular spin interfaces by tuning the occupancy of the molecular orbitals, which carry the spin magnetic moment, can be accomplished by electron doping. We propose a viable route to control the magnetization direction and magnitude of a molecular spin network, in a graphene-mediated architecture, achieved via alkali doping of manganese phthalocyanine (MnPc) molecules assembled on cobalt intercalated under a graphene membrane. The antiparallel magnetic alignment of the MnPc molecules with the underlying Co layer can be switched to a ferromagnetic state by electron doping. Multiplet calculations unveil an enhanced magnetic state of the Mn centers with a 3/2 to 5/2 spin transition induced by alkali doping, as confirmed by the steepening of the hysteresis loops, with higher saturation magnetization values. This new molecular spin configuration can be aligned by an external field, almost independently from the hard-magnet substrate effectively behaving as a free magnetic layer.
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Affiliation(s)
- Giulia Avvisati
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro, 5 00185 Rome, Italy
| | - Pierluigi Gargiani
- ALBA Synchrotron Light Source, Carrer de la Llum, 2-26 08290 Barcelona, Spain
| | - Carlo Mariani
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro, 5 00185 Rome, Italy
| | - Maria Grazia Betti
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro, 5 00185 Rome, Italy
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44
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Schulze KS, Loetzsch R, Rüffer R, Uschmann I, Röhlsberger R, Paulus GG. X-ray dichroism in polyimide caused by non-resonant scattering. JOURNAL OF SYNCHROTRON RADIATION 2021; 28:176-180. [PMID: 33399566 PMCID: PMC7842229 DOI: 10.1107/s1600577520015568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 11/24/2020] [Indexed: 06/12/2023]
Abstract
Dichroism is one of the most important optical effects in both the visible and the X-ray range. Besides absorption, scattering can also contribute to dichroism. This paper demonstrates that, based on the example of polyimide, materials can show tiny dichroism even far from electronic resonances due to scattering. Although the effect is small, it can lead to a measurable polarization change and might have influence on highly sensitive polarimetric experiments.
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Affiliation(s)
- K. S. Schulze
- Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena, Germany
- Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
- GSI Helmholtzzentrum für Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt, Germany
| | - R. Loetzsch
- Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena, Germany
- Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
| | - R. Rüffer
- ESRF – The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9, France
| | - I. Uschmann
- Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena, Germany
- Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
| | - R. Röhlsberger
- Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena, Germany
- Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
- GSI Helmholtzzentrum für Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt, Germany
- Deutsches Elektronen Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - G. G. Paulus
- Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena, Germany
- Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
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45
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Figueroa AI, Bonell F, Cuxart MG, Valvidares M, Gargiani P, van der Laan G, Mugarza A, Valenzuela SO. Absence of Magnetic Proximity Effect at the Interface of Bi_{2}Se_{3} and (Bi,Sb)_{2}Te_{3} with EuS. PHYSICAL REVIEW LETTERS 2020; 125:226801. [PMID: 33315425 DOI: 10.1103/physrevlett.125.226801] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 09/02/2020] [Accepted: 10/16/2020] [Indexed: 06/12/2023]
Abstract
We performed x-ray magnetic circular dichroism (XMCD) measurements on heterostructures comprising topological insulators (TIs) of the (Bi,Sb)_{2}(Se,Te)_{3} family and the magnetic insulator EuS. XMCD measurements allow us to investigate element-selective magnetic proximity effects at the very TI/EuS interface. A systematic analysis reveals that there is neither significant induced magnetism within the TI nor an enhancement of the Eu magnetic moment at such interface. The induced magnetic moments in Bi, Sb, Te, and Se sites are lower than the estimated detection limit of the XMCD measurements of ∼10^{-3} μ_{B}/at.
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Affiliation(s)
- A I Figueroa
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - F Bonell
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - M G Cuxart
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Universitat Autònoma de Barcelona (UAB), Bellaterra 08193, Spain
| | - M Valvidares
- ALBA Synchrotron Light Source, Barcelona 08290, Spain
| | - P Gargiani
- ALBA Synchrotron Light Source, Barcelona 08290, Spain
| | - G van der Laan
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - A Mugarza
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain
| | - S O Valenzuela
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain
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46
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Kumar K, Mishra SK, Baev I, Martins M, Pandey D. Evidence for the coexistence of spin-glass and ferrimagnetic phases in BaFe 12O 19 due to basal plane freezing. Chem Commun (Camb) 2020; 56:14897-14900. [PMID: 33180068 DOI: 10.1039/d0cc03582c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present here the results of low-temperature magnetization and X-ray magnetic circular dichroism studies on the single crystals of BaFe12O19 which reveal for the first time the emergence of a spin glass phase, in coexistence with a long-range ordered ferrimagnetic phase, due to the freezing of the basal plane spin component.
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Affiliation(s)
- Keshav Kumar
- School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi, 221005, India.
| | - Shrawan Kumar Mishra
- School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi, 221005, India.
| | - Ivan Baev
- Universität Hamburg, Institut für Experimentalphysik Luruper Chaussee 149, D-22761, Hamburg, Germany
| | - Michael Martins
- Universität Hamburg, Institut für Experimentalphysik Luruper Chaussee 149, D-22761, Hamburg, Germany
| | - Dhananjai Pandey
- School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi, 221005, India.
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47
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Burn DM, Zhang SL, Yu GQ, Guang Y, Chen HJ, Qiu XP, van der Laan G, Hesjedal T. Depth-Resolved Magnetization Dynamics Revealed by X-Ray Reflectometry Ferromagnetic Resonance. PHYSICAL REVIEW LETTERS 2020; 125:137201. [PMID: 33034462 DOI: 10.1103/physrevlett.125.137201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/29/2020] [Accepted: 08/13/2020] [Indexed: 06/11/2023]
Abstract
Magnetic multilayers offer diverse opportunities for the development of ultrafast functional devices through advanced interface and layer engineering. Nevertheless, a method for determining their dynamic properties as a function of depth throughout such stacks has remained elusive. By probing the ferromagnetic resonance modes with element-selective soft x-ray resonant reflectivity, we gain access to the magnetization dynamics as a function of depth. Most notably, using reflectometry ferromagnetic resonance, we find a phase lag between the coupled ferromagnetic layers in [CoFeB/MgO/Ta]_{4} multilayers that is invisible to other techniques. The use of reflectometry ferromagnetic resonance enables the time-resolved and depth-resolved probing of the complex magnetization dynamics of a wide range of functional magnetic heterostructures with absorption edges in the soft x-ray wavelength regime.
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Affiliation(s)
- D M Burn
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - S L Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 200031, China
| | - G Q Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Y Guang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - H J Chen
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - X P Qiu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - G van der Laan
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - T Hesjedal
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
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48
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Lafuerza S, Carlantuono A, Retegan M, Glatzel P. Chemical Sensitivity of Kβ and Kα X-ray Emission from a Systematic Investigation of Iron Compounds. Inorg Chem 2020; 59:12518-12535. [PMID: 32830953 DOI: 10.1021/acs.inorgchem.0c01620] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
K-fluorescence X-ray emission spectroscopy (XES) is receiving growing interest in all fields of natural sciences to investigate the local spin. The spin sensitivity in Kβ (Kα) XES stems from the exchange interaction between the unpaired 3p (2p) and the 3d electrons, which is greater for Kβ than for Kα. We present a thorough investigation of a large number of iron-bearing compounds. The experimental spectra were analyzed in terms of commonly used quantitative parameters (Kβ1,3-first moment, Kα1-full width at half-maximum, and integrated absolute difference -IAD-), and we carefully examined the difference spectra. Multiplet calculations were also performed to elucidate the underlying mechanisms that lead to the chemical sensitivity. Our results confirm a strong influence of covalency on both Kβ and Kα lines. We establish a reliable spin sensitivity of Kβ XES as it is dominated by the exchange interaction, whose variations can be quantified by either Kβ1,3-first moment or Kβ-IAD and result in a systematic difference signal line shape. We find an exception in the Kβ XES of Fe3+ and Fe2+ in water solution, where a new difference spectrum is identified that cannot be reproduced by scaling the exchange integrals. We explain this by strong differences in orbital mixing between the valence orbitals. This result calls for caution in the interpretation of Kβ XES spectral changes as due to spin variations without a careful analysis of the line shape. For Kα XES, the smaller exchange interaction and the influence of other electron-electron interactions make it difficult to extract a quantity that directly relates to the spin.
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Affiliation(s)
- Sara Lafuerza
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, Grenoble, France
| | - Andrea Carlantuono
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Marius Retegan
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, Grenoble, France
| | - Pieter Glatzel
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, Grenoble, France
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49
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Sundman A, Vitzthum AL, Adaktylos-Surber K, Figueroa AI, van der Laan G, Daus B, Kappler A, Byrne JM. Effect of Fe-metabolizing bacteria and humic substances on magnetite nanoparticle reactivity towards arsenic and chromium. JOURNAL OF HAZARDOUS MATERIALS 2020; 384:121450. [PMID: 31759758 DOI: 10.1016/j.jhazmat.2019.121450] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/08/2019] [Accepted: 10/09/2019] [Indexed: 06/10/2023]
Abstract
Magnetite is a magnetic, Fe(II)-Fe(III)-mineral formed through abiogenic and biogenic pathways. It constitutes an attractive material for remediation due to its reactivity, large surface-area-to-volume ratio when present as nanoparticles, and magnetic recoverability. Magnetite can be repeatedly microbially oxidized or reduced, but it is unclear how this influences the reactivity of magnetite towards toxic metal or metalloid contaminants. In this study, magnetite (both abiogenic and biogenic) was exposed to microbial Fe(II) oxidation and Fe(III) reduction, before reacted with hexavalent chromium (Cr(VI)) or pentavalent arsenic (As(V)). Results showed microbial reduction of both magnetite types improved the removal rate of Cr(VI) from solution, though surprisingly microbial Fe(II)-oxidation also showed enhanced reactivity towards Cr(VI) compared to un-treated magnetite. Synchrotron based analysis confirmed the formation of Cr(III) at the surface of the magnetite. Reactivity with As was less dramatic and showed un-treated material was able to remove As(V) from solution faster than microbially Fe(III)-reduced and Fe(II)-oxidized magnetite. The presence of humic substances was also shown to lead to a decreased reactivity of biogenic and abiogenic magnetite towards As(V) and Cr(VI). Our results imply that Fe-metabolizing bacteria influence the immobilization of contaminants and should be considered when evaluating remediation schemes, especially where Fe-metabolizing bacteria are active.
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Affiliation(s)
- Anneli Sundman
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen, Germany
| | - Anna-Lena Vitzthum
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen, Germany
| | - Konstantin Adaktylos-Surber
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen, Germany
| | | | | | - Birgit Daus
- Department Analytical Chemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Andreas Kappler
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen, Germany
| | - James M Byrne
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen, Germany.
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50
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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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