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Safari MR, Matthes F, Caciuc V, Atodiresei N, Schneider CM, Ernst KH, Bürgler DE. Enantioselective Adsorption on Magnetic Surfaces. Adv Mater 2024; 36:e2308666. [PMID: 38153192 DOI: 10.1002/adma.202308666] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/29/2023] [Indexed: 12/29/2023]
Abstract
From the beginning of molecular theory, the interplay of chirality and magnetism has intrigued scientists. There is still the question if enantiospecific adsorption of chiral molecules occurs on magnetic surfaces. Enantiomer discrimination was conjectured to arise from chirality-induced spin separation within the molecules and exchange interaction with the substrate's magnetization. Here, it is shown that single helical aromatic hydrocarbons undergo enantioselective adsorption on ferromagnetic cobalt surfaces. Spin and chirality sensitive scanning tunneling microscopy reveals that molecules of opposite handedness prefer adsorption onto cobalt islands with opposite out-of-plane magnetization. As mobility ceases in the final chemisorbed state, it is concluded that enantioselection must occur in a physisorbed transient precursor state. State-of-the-art spin-resolved ab initio simulations support this scenario by refuting enantio-dependent chemisorption energies. These findings demonstrate that van der Waals interaction should also include spin-fluctuations which are crucial for molecular magnetochiral processes.
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Affiliation(s)
- Mohammad Reza Safari
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Jülich Aachen Research Alliance (JARA-FIT), Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Frank Matthes
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Jülich Aachen Research Alliance (JARA-FIT), Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Vasile Caciuc
- Peter Grünberg Institute and Institute for Advanced Simulation, Quantum Theory of Materials (PGI-1/IAS-1), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Nicolae Atodiresei
- Peter Grünberg Institute and Institute for Advanced Simulation, Quantum Theory of Materials (PGI-1/IAS-1), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Claus M Schneider
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Jülich Aachen Research Alliance (JARA-FIT), Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425, Jülich, Germany
- Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Karl-Heinz Ernst
- Molecular Surface Science Group, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600, Dübendorf, Switzerland
- Nanosurf Laboratory, Institute of Physics, The Czech Academy of Sciences, 16200, Prague, Czech Republic
- Institut für Chemie, Universität Zürich, 8057, Zürich, Switzerland
| | - Daniel E Bürgler
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Jülich Aachen Research Alliance (JARA-FIT), Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425, Jülich, Germany
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2
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Ali H, Rusz J, Bürgler DE, Adam R, Schneider CM, Tai CW, Thersleff T. Noise-dependent bias in quantitative STEM-EMCD experiments revealed by bootstrapping. Ultramicroscopy 2024; 257:113891. [PMID: 38043363 DOI: 10.1016/j.ultramic.2023.113891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 11/13/2023] [Accepted: 11/23/2023] [Indexed: 12/05/2023]
Abstract
Electron magnetic circular dichroism (EMCD) is a powerful technique for estimating element-specific magnetic moments of materials on nanoscale with the potential to reach atomic resolution in transmission electron microscopes. However, the fundamentally weak EMCD signal strength complicates quantification of magnetic moments, as this requires very high precision, especially in the denominator of the sum rules. Here, we employ a statistical resampling technique known as bootstrapping to an experimental EMCD dataset to produce an empirical estimate of the noise-dependent error distribution resulting from application of EMCD sum rules to bcc iron in a 3-beam orientation. We observe clear experimental evidence that noisy EMCD signals preferentially bias the estimation of magnetic moments, further supporting this with error distributions produced by Monte-Carlo simulations. Finally, we propose guidelines for the recognition and minimization of this bias in the estimation of magnetic moments.
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Affiliation(s)
- Hasan Ali
- Department of Materials Science and Engineering, Uppsala University, Box 534, Uppsala 751 21, Sweden; Department of Materials and Environmental Chemistry, Stockholm University, Stockholm 106 91, Sweden; Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, Jülich 52425, Germany.
| | - Jan Rusz
- Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala 751 20, Sweden
| | - Daniel E Bürgler
- Peter Grünberg Institut, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Roman Adam
- Peter Grünberg Institut, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Claus M Schneider
- Peter Grünberg Institut, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Cheuk-Wai Tai
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm 106 91, Sweden
| | - Thomas Thersleff
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm 106 91, Sweden
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3
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Safari MR, Matthes F, Schneider CM, Ernst KH, Bürgler DE. Spin-Selective Electron Transport Through Single Chiral Molecules. Small 2023:e2308233. [PMID: 38050945 DOI: 10.1002/smll.202308233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 10/30/2023] [Indexed: 12/07/2023]
Abstract
The interplay between chirality and magnetism is a source of fascination among scientists for over a century. In recent years, chirality-induced spin selectivity (CISS) has attracted renewed interest. It is observed that electron transport through layers of homochiral molecules leads to a significant spin polarization of several tens of percent. Despite the abundant experimental evidence gathered through mesoscopic transport measurements, the exact mechanism behind CISS remains elusive. This study reports spin-selective electron transport through single helical aromatic hydrocarbons that are sublimed in vacuo onto ferromagnetic cobalt surfaces and examined with spin-polarized scanning tunneling microscopy (SP-STM) at a temperature of 5 K. Direct comparison of two enantiomers under otherwise identical conditions revealed magnetochiral conductance asymmetries of up to 50% when either the molecular handedness is exchanged or the magnetization direction of the STM tip or Co substrate is reversed. Importantly, the results rule out electron-phonon coupling and ensemble effects as primary mechanisms responsible for CISS.
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Affiliation(s)
- Mohammad Reza Safari
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Jülich Aachen Research Alliance (JARA-FIT), Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Frank Matthes
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Jülich Aachen Research Alliance (JARA-FIT), Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Claus M Schneider
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Jülich Aachen Research Alliance (JARA-FIT), Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425, Jülich, Germany
- Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Karl-Heinz Ernst
- Molecular Surface Science Group, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600, Dübendorf, Switzerland
- Nanosurf Laboratory, Institute of Physics, The Czech Academy of Sciences, 16200, Prague, Czech Republic
- Institut für Chemie, Universität Zürich, 8057, Zürich, Switzerland
| | - Daniel E Bürgler
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Jülich Aachen Research Alliance (JARA-FIT), Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425, Jülich, Germany
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4
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Safari MR, Matthes F, Ernst KH, Bürgler DE, Schneider CM. Deposition of Chiral Heptahelicene Molecules on Ferromagnetic Co and Fe Thin-Film Substrates. Nanomaterials (Basel) 2022; 12:3281. [PMID: 36234411 PMCID: PMC9565510 DOI: 10.3390/nano12193281] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/02/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
The discovery of chirality-induced spin selectivity (CISS), resulting from an interaction between the electron spin and handedness of chiral molecules, has sparked interest in surface-adsorbed chiral molecules due to potential applications in spintronics, enantioseparation, and enantioselective chemical or biological processes. We study the deposition of chiral heptahelicene by sublimation under ultra-high vacuum onto bare Cu(111), Co bilayer nanoislands on Cu(111), and Fe bilayers on W(110) by low-temperature spin-polarized scanning tunneling microscopy/spectroscopy (STM/STS). In all cases, the molecules remain intact and adsorb with the proximal phenanthrene group aligned parallel to the surface. Three degenerate in-plane orientations on Cu(111) and Co(111), reflecting substrate symmetry, and only two on Fe(110), i.e., fewer than symmetry permits, indicate a specific adsorption site for each substrate. Heptahelicene physisorbs on Cu(111) but chemisorbs on Co(111) and Fe(110) bilayers, which nevertheless remain for the sub-monolayer coverage ferromagnetic and magnetized out-of-plane. We are able to determine the handedness of individual molecules chemisorbed on Fe(110) and Co(111), as previously reported for less reactive Cu(111). The demonstrated deposition control and STM/STS imaging capabilities for heptahelicene on Co/Cu(111) and Fe/W(110) substrate systems lay the foundation for studying CISS in ultra-high vacuum and on the microscopic level of single molecules in controlled atomic configurations.
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Affiliation(s)
- Mohammad Reza Safari
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52428 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Frank Matthes
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52428 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Karl-Heinz Ernst
- Molecular Surface Science Group, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Nanosurf Laboratory, Institute of Physics, The Czech Academy of Sciences, 16200 Prague, Czech Republic
| | - Daniel E. Bürgler
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52428 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Claus M. Schneider
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52428 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
- Fakultät für Physik, Universität Duisburg-Essen, 47057 Duisburg, Germany
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5
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Kerres P, Zhou Y, Vaishnav H, Raghuwanshi M, Wang J, Häser M, Pohlmann M, Cheng Y, Schön CF, Jansen T, Bellin C, Bürgler DE, Jalil AR, Ringkamp C, Kowalczyk H, Schneider CM, Shukla A, Wuttig M. Scaling and Confinement in Ultrathin Chalcogenide Films as Exemplified by GeTe. Small 2022; 18:e2201753. [PMID: 35491494 DOI: 10.1002/smll.202201753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Indexed: 06/14/2023]
Abstract
Chalcogenides such as GeTe, PbTe, Sb2 Te3 , and Bi2 Se3 are characterized by an unconventional combination of properties enabling a plethora of applications ranging from thermo-electrics to phase change materials, topological insulators, and photonic switches. Chalcogenides possess pronounced optical absorption, relatively low effective masses, reasonably high electron mobilities, soft bonds, large bond polarizabilities, and low thermal conductivities. These remarkable characteristics are linked to an unconventional bonding mechanism characterized by a competition between electron delocalization and electron localization. Confinement, that is, the reduction of the sample dimension as realized in thin films should alter this competition and modify chemical bonds and the resulting properties. Here, pronounced changes of optical and vibrational properties are demonstrated for crystalline films of GeTe, while amorphous films of GeTe show no similar thickness dependence. For crystalline films, this thickness dependence persists up to remarkably large thicknesses above 15 nm. X-ray diffraction and accompanying simulations employing density functional theory relate these changes to thickness dependent structural (Peierls) distortions, due to an increased electron localization between adjacent atoms upon reducing the film thickness. A thickness dependence and hence potential to modify film properties for all chalcogenide films with a similar bonding mechanism is expected.
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Affiliation(s)
- Peter Kerres
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
| | - Yiming Zhou
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
| | - Hetal Vaishnav
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
- Peter Grünberg Institute-JARA-Institute Energy-Efficient Information Technology (PGI-10), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Mohit Raghuwanshi
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
- Peter Grünberg Institute-JARA-Institute Energy-Efficient Information Technology (PGI-10), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Jiangjing Wang
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
- Center for Alloy Innovation and Design, Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Maria Häser
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
| | - Marc Pohlmann
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
| | - Yudong Cheng
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
- Center for Alloy Innovation and Design, Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | | | - Thomas Jansen
- Peter Grünberg Institute-Electronic Properties (PGI-6), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Christophe Bellin
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, MNHN, Paris, F-75005, France
| | - Daniel E Bürgler
- Peter Grünberg Institute-Electronic Properties (PGI-6), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Abdur Rehman Jalil
- Peter Grünberg Institute-Semiconductor Nanoelectronics (PGI-6), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Christoph Ringkamp
- Peter Grünberg Institute-Semiconductor Nanoelectronics (PGI-6), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Hugo Kowalczyk
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, MNHN, Paris, F-75005, France
| | - Claus M Schneider
- Peter Grünberg Institute-Electronic Properties (PGI-6), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
- JARA-FIT, RWTH Aachen University, 52056, Aachen, Germany
| | - Abhay Shukla
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, MNHN, Paris, F-75005, France
| | - Matthias Wuttig
- Peter Grünberg Institute-JARA-Institute Energy-Efficient Information Technology (PGI-10), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
- JARA-FIT, RWTH Aachen University, 52056, Aachen, Germany
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6
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Metzelaars M, Schleicher S, Hattori T, Borca B, Matthes F, Sanz S, Bürgler DE, Rawson J, Schneider CM, Kögerler P. Cyclophane with eclipsed pyrene units enables construction of spin interfaces with chemical accuracy. Chem Sci 2021; 12:8430-8437. [PMID: 34221324 PMCID: PMC8221062 DOI: 10.1039/d1sc01036k] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Advanced functionality in molecular electronics and spintronics is orchestrated by exact molecular arrangements at metal surfaces, but the strategies for constructing such arrangements remain limited. Here, we report the synthesis and surface hybridization of a cyclophane that comprises two pyrene groups fastened together by two ferrocene pillars. Crystallographic structure analysis revealed pyrene planes separated by ∼352 pm and stacked in an eclipsed geometry that approximates the rare configuration of AA-stacked bilayer graphene. We deposited this cyclophane onto surfaces of Cu(111) and Co(111) at submonolayer coverage and studied the resulting hybrid entities with scanning tunnelling microscopy (STM). We found distinct characteristics of this cyclophane on each metal surface: on non-magnetic Cu(111), physisorption occurred and the two pyrene groups remained electronically coupled to each other; on ferromagnetic Co(111) nanoislands, chemisorption occurred and the two pyrene groups became electronically decoupled. Spin-polarized STM measurements revealed that the ferrocene groups had spin polarization opposite to that of the surrounding Co metal, while the pyrene stack had no spin polarization. Comparisons to the non-stacked analogue comprising only one pyrene group bolster our interpretation of the cyclophane's STM features. The design strategy presented herein can be extended to realize versatile, three-dimensional platforms in single-molecule electronics and spintronics. A chemical strategy for the bottom-up construction of 3D spin interfaces is presented. Scanning tunnelling microscopy reveals distinct electronic features of a cyclophane with precisely designed pi-stacking on ferromagnetic Co(111) nanoislands.![]()
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Affiliation(s)
- Marvin Metzelaars
- Institute of Inorganic Chemistry, RWTH Aachen University 52074 Aachen Germany
| | | | - Takuma Hattori
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich 52428 Jülich Germany
| | - Bogdana Borca
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich 52428 Jülich Germany .,National Institute of Materials Physics Atomistilor 405A, Magurele 077125 Ilfov Romania
| | - Frank Matthes
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich 52428 Jülich Germany
| | - Sergio Sanz
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich 52428 Jülich Germany
| | - Daniel E Bürgler
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich 52428 Jülich Germany
| | - Jeff Rawson
- Institute of Inorganic Chemistry, RWTH Aachen University 52074 Aachen Germany.,Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich 52428 Jülich Germany
| | - Claus M Schneider
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich 52428 Jülich Germany
| | - Paul Kögerler
- Institute of Inorganic Chemistry, RWTH Aachen University 52074 Aachen Germany.,Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich 52428 Jülich Germany
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7
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Thersleff T, Schönström L, Tai CW, Adam R, Bürgler DE, Schneider CM, Muto S, Rusz J. Single-pass STEM-EMCD on a zone axis using a patterned aperture: progress in experimental and data treatment methods. Sci Rep 2019; 9:18170. [PMID: 31796786 PMCID: PMC6890689 DOI: 10.1038/s41598-019-53373-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/22/2019] [Indexed: 11/08/2022] Open
Abstract
Measuring magnetic moments in ferromagnetic materials at atomic resolution is theoretically possible using the electron magnetic circular dichroism (EMCD) technique in a (scanning) transmission electron microscope ((S)TEM). However, experimental and data processing hurdles currently hamper the realization of this goal. Experimentally, the sample must be tilted to a zone-axis orientation, yielding a complex distribution of magnetic scattering intensity, and the same sample region must be scanned multiple times with sub-atomic spatial registration necessary at each pass. Furthermore, the weak nature of the EMCD signal requires advanced data processing techniques to reliably detect and quantify the result. In this manuscript, we detail our experimental and data processing progress towards achieving single-pass zone-axis EMCD using a patterned aperture. First, we provide a comprehensive data acquisition and analysis strategy for this and other EMCD experiments that should scale down to atomic resolution experiments. Second, we demonstrate that, at low spatial resolution, promising EMCD candidate signals can be extracted, and that these are sensitive to both crystallographic orientation and momentum transfer.
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Affiliation(s)
- Thomas Thersleff
- Stockholm University, Department of Materials and Environmental Chemistry, 10691, Stockholm, Sweden.
| | - Linus Schönström
- Stockholm University, Department of Materials and Environmental Chemistry, 10691, Stockholm, Sweden
- Uppsala University, Department of Physics and Astronomy, Box 516, 75120, Uppsala, Sweden
| | - Cheuk-Wai Tai
- Stockholm University, Department of Materials and Environmental Chemistry, 10691, Stockholm, Sweden
| | - Roman Adam
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut, D-52425, Jülich, Germany
| | - Daniel E Bürgler
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut, D-52425, Jülich, Germany
| | - Claus M Schneider
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut, D-52425, Jülich, Germany
| | - Shunsuke Muto
- Nagoya University, Institute of Materials and Systems for Sustainability, Nagoya, 464-8603, Japan
| | - Ján Rusz
- Uppsala University, Department of Physics and Astronomy, Box 516, 75120, Uppsala, Sweden
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8
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Rusz J, Muto S, Spiegelberg J, Adam R, Tatsumi K, Bürgler DE, Oppeneer PM, Schneider CM. Erratum: Magnetic measurements with atomic-plane resolution. Nat Commun 2016; 7:13159. [PMID: 27703183 PMCID: PMC5059487 DOI: 10.1038/ncomms13159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
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9
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Rusz J, Muto S, Spiegelberg J, Adam R, Tatsumi K, Bürgler DE, Oppeneer PM, Schneider CM. Magnetic measurements with atomic-plane resolution. Nat Commun 2016; 7:12672. [PMID: 27578421 PMCID: PMC5013673 DOI: 10.1038/ncomms12672] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 07/21/2016] [Indexed: 11/09/2022] Open
Abstract
Rapid development of magnetic nanotechnologies calls for experimental techniques capable of providing magnetic information with subnanometre spatial resolution. Available probes of magnetism either detect only surface properties, such as spin-polarized scanning tunnelling microscopy, magnetic force microscopy or spin-polarized low-energy electron microscopy, or they are bulk probes with limited spatial resolution or quantitativeness, such as X-ray magnetic circular dichroism or classical electron magnetic circular dichroism (EMCD). Atomic resolution EMCD methods have been proposed, although not yet experimentally realized. Here, we demonstrate an EMCD technique with an atomic size electron probe utilizing a probe-corrected scanning transmission electron microscope in its standard operation mode. The crucial element of the method is a ramp in the phase of the electron beam wavefunction, introduced by a controlled beam displacement. We detect EMCD signals with atomic-plane resolution, thereby bringing near-atomic resolution magnetic circular dichroism spectroscopy to hundreds of laboratories worldwide. It has been predicted that electron beam probes may allow for the imaging of magnetism with atomic-scale resolution. Here, the authors demonstrate a scanning transmission electron microscopy method capable of resolving magnetic contrast from individual atomic planes.
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Affiliation(s)
- Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Box 516, S-75120 Uppsala, Sweden
| | - Shunsuke Muto
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Jakob Spiegelberg
- Department of Physics and Astronomy, Uppsala University, Box 516, S-75120 Uppsala, Sweden
| | - Roman Adam
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Kazuyoshi Tatsumi
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Daniel E Bürgler
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Peter M Oppeneer
- Department of Physics and Astronomy, Uppsala University, Box 516, S-75120 Uppsala, Sweden
| | - Claus M Schneider
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
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10
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Tesch MF, Gilbert MC, Mertins HC, Bürgler DE, Berges U, Schneider CM. X-ray magneto-optical polarization spectroscopy: an analysis from the visible region to the x-ray regime. Appl Opt 2013; 52:4294-4310. [PMID: 23842173 DOI: 10.1364/ao.52.004294] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 04/24/2013] [Indexed: 06/02/2023]
Abstract
An ultra-high vacuum compatible multipurpose chamber for magneto-optical reflection and transmission experiments with polarization analysis on magnetic systems is introduced. It is applicable in a broad photon energy range from the visible to the soft x-ray regime and for a wide angular range from grazing to normal incidence. It exploits a novel magnetization device based on rotating permanent magnets, which generates tuneable magnetic fields up to 570 mT in longitudinal, transverse and polar geometry. The unique combination of these features enables the feasibility of all typical magneto-optical spectroscopy techniques as T-MOKE, L-MOKE, P-MOKE, x-ray magneto optical linear dichroism, x-ray magnetic circular dichroism in reflection and Kerr polarization-spectroscopy, which is demonstrated for Co with focus on the Co 3p edges.
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Affiliation(s)
- M F Tesch
- University of Applied Sciences Münster, Steinfurt, Germany.
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Heedt S, Morgan C, Weis K, Bürgler DE, Calarco R, Hardtdegen H, Grützmacher D, Schäpers T. Electrical spin injection into InN semiconductor nanowires. Nano Lett 2012; 12:4437-4443. [PMID: 22889199 DOI: 10.1021/nl301052g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report on the conditions necessary for the electrical injection of spin-polarized electrons into indium nitride nanowires synthesized from the bottom up by molecular beam epitaxy. The presented results mark the first unequivocal evidence of spin injection into III-V semiconductor nanowires. Utilizing a newly developed preparation scheme, we are able to surmount shadowing effects during the metal deposition. Thus, we avoid strong local anisotropies that arise if the ferromagnetic leads are wrapping around the nanowire. Using a combination of various complementary techniques, inter alia the local Hall effect, we carried out a comprehensive investigation of the coercive fields and switching behaviors of the cobalt micromagnetic spin probes. This enables the identification of a range of aspect ratios in which the mechanism of magnetization reversal is single domain switching. Lateral nanowire spin valves were prepared. The spin relaxation length is demonstrated to be about 200 nm, which provides an incentive to pursue the route toward nanowire spin logic devices.
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Affiliation(s)
- S Heedt
- Peter Grünberg Institut (PGI-9) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich, Germany.
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12
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Seemann KM, Freimuth F, Zhang H, Blügel S, Mokrousov Y, Bürgler DE, Schneider CM. Origin of the planar Hall effect in nanocrystalline Co60Fe20B20. Phys Rev Lett 2011; 107:086603. [PMID: 21929187 DOI: 10.1103/physrevlett.107.086603] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Indexed: 05/31/2023]
Abstract
An angle dependent analysis of the planar Hall effect (PHE) in nanocrystalline single-domain Co(60)Fe(20)B(20) thin films is reported. In a combined experimental and theoretical study we show that the transverse resistivity of the PHE is entirely driven by anisotropic magnetoresistance (AMR). Our results for Co(60)Fe(20)B(20) obtained from first principles theory in conjunction with a Boltzmann transport model take into account the nanocrystallinity and the presence of 20 at. % boron. The ab initio AMR ratio of 0.12% agrees well with the experimental value of 0.22%. Furthermore, we experimentally demonstrate that the anomalous Hall effect contributes negligibly in the present case.
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Affiliation(s)
- K M Seemann
- Peter Grünberg Institute (PGI-6) and Jülich-Aachen Research Alliance (JARA-FIT), Forschungszentrum Jülich, D-52425 Jülich, Germany.
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Gareev RR, Bürgler DE, Buchmeier M, Olligs D, Schreiber R, Grünberg P. Metallic-type oscillatory interlayer exchange coupling across an epitaxial FeSi spacer. Phys Rev Lett 2001; 87:157202. [PMID: 11580722 DOI: 10.1103/physrevlett.87.157202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2000] [Indexed: 05/23/2023]
Abstract
We study interlayer exchange coupling in epitaxial Fe/Fe(0.56)Si(0.44)/Fe trilayers. Iron-silicide spacers with high structural and compositional homogeneity for thicknesses up to 34 A are grown by coevaporation from two electron-beam sources. The coupling strength oscillates with spacer thickness for temperatures from 20 to 300 K with two antiferromagnetic maxima at 12 and 26 A, and it clearly increases with decreasing temperature down to 80 K. We conclude that the coupling across ordered Fe(1-x)Si(x) ( x approximately 0.5) is described by the conventional theory of interlayer coupling across metallic spacers.
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Affiliation(s)
- R R Gareev
- Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
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Schaub TM, Bürgler DE, Güntherodt H, Suck JB. Quasicrystalline structure of icosahedral Al68Pd23Mn9 resolved by scanning tunneling microscopy. Phys Rev Lett 1994; 73:1255-1258. [PMID: 10057664 DOI: 10.1103/physrevlett.73.1255] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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