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Volkov OM, Pylypovskyi OV, Porrati F, Kronast F, Fernandez-Roldan JA, Kákay A, Kuprava A, Barth S, Rybakov FN, Eriksson O, Lamb-Camarena S, Makushko P, Mawass MA, Shakeel S, Dobrovolskiy OV, Huth M, Makarov D. Three-dimensional magnetic nanotextures with high-order vorticity in soft magnetic wireframes. Nat Commun 2024; 15:2193. [PMID: 38467623 PMCID: PMC10928081 DOI: 10.1038/s41467-024-46403-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 02/22/2024] [Indexed: 03/13/2024] Open
Abstract
Additive nanotechnology enable curvilinear and three-dimensional (3D) magnetic architectures with tunable topology and functionalities surpassing their planar counterparts. Here, we experimentally reveal that 3D soft magnetic wireframe structures resemble compact manifolds and accommodate magnetic textures of high order vorticity determined by the Euler characteristic, χ. We demonstrate that self-standing magnetic tetrapods (homeomorphic to a sphere; χ = + 2) support six surface topological solitons, namely four vortices and two antivortices, with a total vorticity of + 2 equal to its Euler characteristic. Alternatively, wireframe structures with one loop (homeomorphic to a torus; χ = 0) possess equal number of vortices and antivortices, which is relevant for spin-wave splitters and 3D magnonics. Subsequent introduction of n holes into the wireframe geometry (homeomorphic to an n-torus; χ < 0) enables the accommodation of a virtually unlimited number of antivortices, which suggests their usefulness for non-conventional (e.g., reservoir) computation. Furthermore, complex stray-field topologies around these objects are of interest for superconducting electronics, particle trapping and biomedical applications.
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Affiliation(s)
- Oleksii M Volkov
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany.
| | - Oleksandr V Pylypovskyi
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany.
- Kyiv Academic University, 03142, Kyiv, Ukraine.
| | - Fabrizio Porrati
- Physikalisches Institut, Johann Wolfgang Goethe-Universität Frankfurt am Main, Max-von-Laue-Str. 1, 60438, Frankfurt am Main, Germany.
| | - Florian Kronast
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489, Berlin, Germany
| | - Jose A Fernandez-Roldan
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Attila Kákay
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Alexander Kuprava
- Physikalisches Institut, Johann Wolfgang Goethe-Universität Frankfurt am Main, Max-von-Laue-Str. 1, 60438, Frankfurt am Main, Germany
| | - Sven Barth
- Physikalisches Institut, Johann Wolfgang Goethe-Universität Frankfurt am Main, Max-von-Laue-Str. 1, 60438, Frankfurt am Main, Germany
| | - Filipp N Rybakov
- Department of Physics and Astronomy, Uppsala University, Box-516, Uppsala, SE-751 20, Sweden
| | - Olle Eriksson
- Department of Physics and Astronomy, Uppsala University, Box-516, Uppsala, SE-751 20, Sweden
- Wallenberg Initiative Materials Science for Sustainability, Uppsala University, 75121, Uppsala, Sweden
| | - Sebastian Lamb-Camarena
- University of Vienna, Faculty of Physics, Nanomagnetism and Magnonics, Superconductivity and Spintronics Laboratory, Währinger Str. 17, 1090, Vienna, Austria
- University of Vienna, Vienna Doctoral School in Physics, Boltzmanngasse 5, A-1090, Vienna, Austria
| | - Pavlo Makushko
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Mohamad-Assaad Mawass
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489, Berlin, Germany
- Department of Interface Science, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4 - 6, 14195, Berlin, Germany
| | - Shahrukh Shakeel
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Oleksandr V Dobrovolskiy
- University of Vienna, Faculty of Physics, Nanomagnetism and Magnonics, Superconductivity and Spintronics Laboratory, Währinger Str. 17, 1090, Vienna, Austria
| | - Michael Huth
- Physikalisches Institut, Johann Wolfgang Goethe-Universität Frankfurt am Main, Max-von-Laue-Str. 1, 60438, Frankfurt am Main, Germany
| | - Denys Makarov
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany.
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2
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Fullerton J, McCray ARC, Petford-Long AK, Phatak C. Understanding the Effect of Curvature on the Magnetization Reversal of Three-Dimensional Nanohelices. NANO LETTERS 2024; 24:2481-2487. [PMID: 38373326 DOI: 10.1021/acs.nanolett.3c04172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Comprehending the interaction between geometry and magnetism in three-dimensional (3D) nanostructures is important to understand the fundamental physics of domain wall (DW) formation and pinning. Here, we use focused-electron-beam-induced deposition to fabricate magnetic nanohelices with increasing helical curvature with height. Using electron tomography and Lorentz transmission electron microscopy, we reconstruct the 3D structure and magnetization of the nanohelices. The surface curvature, helical curvature, and torsion of the nanohelices are then quantified from the tomographic reconstructions. Furthermore, by using the experimental 3D reconstructions as inputs for micromagnetic simulations, we can reveal the influence of surface and helical curvature on the magnetic reversal mechanism. Hence, we can directly correlate the magnetic behavior of a 3D nanohelix to its experimental structure. These results demonstrate how the control of geometry in nanohelices can be utilized in the stabilization of DWs and control of the response of the nanostructure to applied magnetic fields.
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Affiliation(s)
- John Fullerton
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Arthur R C McCray
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
| | - Amanda K Petford-Long
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Charudatta Phatak
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
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3
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Li X, Wang Z, Lei Z, Ding W, Shi X, Yan J, Ku J. Magnetic characterization techniques and micromagnetic simulations of magnetic nanostructures: from zero to three dimensions. NANOSCALE 2023. [PMID: 37981862 DOI: 10.1039/d3nr04493a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2023]
Abstract
The investigation of the magnetic characteristics of magnetic nanostructures (MNs) in various dimensions is a crucial direction of research in nanomagnetism, with MNs belonging to various dimensions exhibiting magnetic properties related to their geometry. A better understanding of these magnetic properties is required for MN manipulation. The primary tools for researching MNs are magnetic characterisation techniques with great spatial resolution and spin sensitivity. Micromagnetic simulation is another technique that minimises experimental costs, while providing information on the magnetic structure and magnetic behaviour, and has enormous potential for predicting, validating, and extending the magnetic characterisation results. This review first looks at the progress of research into quantitatively characterising the magnetic properties of low-dimensional (including 0D, 1D, and 2D) and 3D MNs in two directions: magnetic characterisation techniques and micromagnetic simulations, with a particular emphasis on the potential for future applications of these techniques. Single magnetic characterization techniques, single micromagnetic simulations, or a mix of both are utilised in these research studies to investigate MNs in a variety of dimensions. How the magnetic characterisation techniques and micromagnetic simulations can be better applied to MNs in various dimensions is then outlined. This discussion has significant application potential for low-dimensional and 3D MNs.
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Affiliation(s)
- Xin Li
- Zijin School of Geology and Mining, Fuzhou University, Fuzhou 350116, China.
- Fujian Key Laboratory of Green Extraction and High-value Utilization of Energy Metals, Fuzhou 350116, China
| | - Zhaolian Wang
- Shandong Huate Magnet Technology Co., Ltd, Weifang 261000, China
| | - Zhongyun Lei
- College of Chemical Engineering, Fuzhou University, Fuzhou 350116, China
| | - Wei Ding
- Zijin School of Geology and Mining, Fuzhou University, Fuzhou 350116, China.
| | - Xiao Shi
- Zijin School of Geology and Mining, Fuzhou University, Fuzhou 350116, China.
| | - Jujian Yan
- Zijin School of Geology and Mining, Fuzhou University, Fuzhou 350116, China.
| | - Jiangang Ku
- Zijin School of Geology and Mining, Fuzhou University, Fuzhou 350116, China.
- Fujian Key Laboratory of Green Extraction and High-value Utilization of Energy Metals, Fuzhou 350116, China
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4
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Bran C, Fernandez-Roldan JA, Moreno JA, Fraile Rodríguez A, Del Real RP, Asenjo A, Saugar E, Marqués-Marchán J, Mohammed H, Foerster M, Aballe L, Kosel J, Vazquez M, Chubykalo-Fesenko O. Domain wall propagation and pinning induced by current pulses in cylindrical modulated nanowires. NANOSCALE 2023; 15:8387-8394. [PMID: 37092798 DOI: 10.1039/d3nr00455d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The future developments in 3D magnetic nanotechnology require the control of domain wall dynamics by means of current pulses. While this has been extensively studied in 2D magnetic strips (planar nanowires), few reports on this exist in cylindrical geometry, where Bloch point domain walls are expected to have intriguing properties. Here, we report an investigation on cylindrical magnetic Ni nanowires with geometrical notches. An experimental work based on synchrotron X-ray magnetic circular dichroism (XMCD) combined with photoemission electron microscopy (PEEM) indicates that large current densities induce domain wall nucleation, while smaller currents move domain walls preferably antiparallel to the current direction. In the region where no pinning centers are present, we found a domain wall velocity of about 1 km s-1. Thermal modelling indicates that large current densities temporarily raise the temperature in the nanowire above the Curie temperature, leading to nucleation of domain walls during the system cooling. Micromagnetic modelling with a spin-torque effect shows that for intermediate current densities, Bloch point domain walls with chirality parallel to the Oersted field propagate antiparallel to the current direction. In other cases, domain walls can be bounced from the notches and/or get pinned outside their positions. We thus found that current is not only responsible for domain wall propagation, but also is a source of pinning due to the Oersted field action.
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Affiliation(s)
- C Bran
- Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, 28049, Spain.
| | - J A Fernandez-Roldan
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - J A Moreno
- King Abdullah University of Science and Technology, Computer Electrical and Mathematical Science and Engineering, Thuwal 23955-6900, Saudi Arabia
| | - A Fraile Rodríguez
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Barcelona, 08028, Spain
- Institut de Nanociencia i Nanotecnologia (IN2UB), Universitat de Barcelona, Barcelona, 08028, Spain
| | - R P Del Real
- Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, 28049, Spain.
| | - A Asenjo
- Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, 28049, Spain.
| | - E Saugar
- Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, 28049, Spain.
| | - J Marqués-Marchán
- Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, 28049, Spain.
| | - H Mohammed
- King Abdullah University of Science and Technology, Computer Electrical and Mathematical Science and Engineering, Thuwal 23955-6900, Saudi Arabia
| | - M Foerster
- ALBA Synchrotron Light Facility, CELLS, Barcelona, 08290, Spain
| | - L Aballe
- ALBA Synchrotron Light Facility, CELLS, Barcelona, 08290, Spain
| | - J Kosel
- King Abdullah University of Science and Technology, Computer Electrical and Mathematical Science and Engineering, Thuwal 23955-6900, Saudi Arabia
- Silicon Austria Labs, Villach 9524, Austria
| | - M Vazquez
- Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, 28049, Spain.
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5
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Fullerton J, Hierro-Rodriguez A, Donnelly C, Sanz-Hernández D, Skoric L, MacLaren DA, Fernández-Pacheco A. Controlled evolution of three-dimensional magnetic states in strongly coupled cylindrical nanowire pairs. NANOTECHNOLOGY 2023; 34:125301. [PMID: 36595337 DOI: 10.1088/1361-6528/aca9d6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 12/07/2022] [Indexed: 06/17/2023]
Abstract
Cylindrical magnetic nanowires are promising systems for the development of three-dimensional spintronic devices. Here, we simulate the evolution of magnetic states during fabrication of strongly-coupled cylindrical nanowires with varying degrees of overlap. By varying the separation between wires, the relative strength of exchange and magnetostatic coupling can be tuned. Hence, we observe the formation of six fundamental states as a function of both inter-wire separation and wire height. In particular, two complex three-dimensional magnetic states, a 3D Landau Pattern and a Helical domain wall, are observed to emerge for intermediate overlap. These two emergent states show complex spin configurations, including a modulated domain wall with both Néel and Bloch character. The competition of magnetic interactions and the parallel growth scheme we follow (growing both wires at the same time) favours the formation of these anti-parallel metastable states. This works shows how the engineering of strongly coupled 3D nanostructures with competing interactions can be used to create complex spin textures.
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Affiliation(s)
- J Fullerton
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom
| | | | - C Donnelly
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - D Sanz-Hernández
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Paris, France
| | - L Skoric
- Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - D A MacLaren
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom
| | - A Fernández-Pacheco
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom
- Instituto de Nanociencia y Materiales de Aragón, CSIC-Universidad de Zaragoza, Zaragoza, Spain
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6
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Fernandez-Roldan JA, Bran C, Asenjo A, Vázquez M, Sorrentino A, Ferrer S, Chubykalo-Fesenko O, Del Real RP. Spatial magnetic imaging of non-axially symmetric vortex domains in cylindrical nanowire by transmission X-ray microscopy. NANOSCALE 2022; 14:13661-13666. [PMID: 36082785 DOI: 10.1039/d2nr03228g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The spatial magnetization texture of a cylindrical nanowire has been determined by Transmission X-ray Microscopy (TXM) and X-ray magnetic circular dichroism (XMCD). For this purpose, nanowires with designed geometry, consisting of CoNi/Ni periodic segments, have been grown by designed electrodeposition into alumina templates. Experimental data allow one to conclude the presence of mono- and trivortex magnetic domains in CoNi segments but, unusually, these states are characterized by an asymmetric XMCD contrast across the nanowire's section. Micromagnetic modelling shows non-trivial three-dimensional structures with ellipsoidal vortex cores and non-axially symmetric magnetization along the nanowire direction. The modelled TXM contrast of micromagnetic structures allows to correlate the experimental asymmetric XMCD contrast to the easy axis direction of the uniaxial magnetocrystalline anisotropy.
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Affiliation(s)
- Jose A Fernandez-Roldan
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, 01328 Dresden, Germany.
| | - Cristina Bran
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain.
| | - Agustina Asenjo
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain.
| | - Manuel Vázquez
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain.
| | | | | | | | - Rafael P Del Real
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain.
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7
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Marqués-Marchán J, Fernandez-Roldan JA, Bran C, Puttock R, Barton C, Moreno JA, Kosel J, Vazquez M, Kazakova O, Chubykalo-Fesenko O, Asenjo A. Distinguishing Local Demagnetization Contribution to the Magnetization Process in Multisegmented Nanowires. NANOMATERIALS 2022; 12:nano12121968. [PMID: 35745306 PMCID: PMC9229024 DOI: 10.3390/nano12121968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 06/03/2022] [Accepted: 06/05/2022] [Indexed: 01/16/2023]
Abstract
Cylindrical magnetic nanowires are promising materials that have the potential to be used in a wide range of applications. The versatility of these nanostructures is based on the tunability of their magnetic properties, which is achieved by appropriately selecting their composition and morphology. In addition, stochastic behavior has attracted attention in the development of neuromorphic devices relying on probabilistic magnetization switching. Here, we present a study of the magnetization reversal process in multisegmented CoNi/Cu nanowires. Nonstandard 2D magnetic maps, recorded under an in-plane magnetic field, produce datasets that correlate with magnetoresistance measurements and micromagnetic simulations. From this process, the contribution of the individual segments to the demagnetization process can be distinguished. The results show that the magnetization reversal in these nanowires does not occur through a single Barkhausen jump, but rather by multistep switching, as individual CoNi segments in the NW undergo a magnetization reversal. The existence of vortex states is confirmed by their footprint in the magnetoresistance and 2D MFM maps. In addition, the stochasticity of the magnetization reversal is analysed. On the one hand, we observe different switching fields among the segments due to a slight variation in geometrical parameters or magnetic anisotropy. On the other hand, the stochasticity is observed in a series of repetitions of the magnetization reversal processes for the same NW under the same conditions.
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Affiliation(s)
- Jorge Marqués-Marchán
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain; (J.M.-M.); (C.B.); (M.V.); (O.C.-F.)
| | - Jose Angel Fernandez-Roldan
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, 01328 Dresden, Germany;
| | - Cristina Bran
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain; (J.M.-M.); (C.B.); (M.V.); (O.C.-F.)
| | - Robert Puttock
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK; (R.P.); (C.B.); (O.K.)
- Department of Physics, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Craig Barton
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK; (R.P.); (C.B.); (O.K.)
| | - Julián A. Moreno
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia;
| | - Jürgen Kosel
- Computer Electrical and Mathematical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia;
- Silicon Austria Labs, Sensor Systems Division, A-9524 Villach, Austria
| | - Manuel Vazquez
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain; (J.M.-M.); (C.B.); (M.V.); (O.C.-F.)
| | - Olga Kazakova
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK; (R.P.); (C.B.); (O.K.)
| | - Oksana Chubykalo-Fesenko
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain; (J.M.-M.); (C.B.); (M.V.); (O.C.-F.)
| | - Agustina Asenjo
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain; (J.M.-M.); (C.B.); (M.V.); (O.C.-F.)
- Correspondence:
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8
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Novel Magnetic Properties in Curved Geometries. NANOMATERIALS 2022; 12:nano12071175. [PMID: 35407293 PMCID: PMC9000637 DOI: 10.3390/nano12071175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 03/25/2022] [Indexed: 02/04/2023]
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9
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Narrow Segment Driven Multistep Magnetization Reversal Process in Sharp Diameter Modulated Fe 67Co 33 Nanowires. NANOMATERIALS 2021; 11:nano11113077. [PMID: 34835841 PMCID: PMC8619352 DOI: 10.3390/nano11113077] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/29/2021] [Accepted: 11/10/2021] [Indexed: 12/04/2022]
Abstract
Magnetic nanomaterials are of great interest due to their potential use in data storage, biotechnology, or spintronic based devices, among others. The control of magnetism at such scale entails complexing the nanostructures by tuning their composition, shape, sizes, or even several of these properties at the same time, in order to search for new phenomena or optimize their performance. An interesting pathway to affect the dynamics of the magnetization reversal in ferromagnetic nanostructures is to introduce geometrical modulations to act as nucleation or pinning centers for the magnetic domain walls. Considering the case of 3D magnetic nanowires, the modulation of the diameter across their length can produce such effect as long as the segment diameter transition is sharp enough. In this work, diameter modulated Fe67Co33 ferromagnetic nanowires have been grown into the prepatterned diameter modulated nanopores of anodized Al2O3 membranes. Their morphological and compositional characterization was carried out by electron-based microscopy, while their magnetic behavior has been measured on both the nanowire array as well as for individual bisegmented nanowires after being released from the alumina template. The magnetic hysteresis loops, together with the evaluation of First Order Reversal Curve diagrams, point out that the magnetization reversal of the bisegmented FeCo nanowires is carried out in two steps. These two stages are interpreted by micromagnetic modeling, where a shell of the wide segment reverses its magnetization first, followed by the reversal of its core together with the narrow segment of the nanowire at once.
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10
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Magnetic Force Microscopy on Nanofibers—Limits and Possible Approaches for Randomly Oriented Nanofiber Mats. MAGNETOCHEMISTRY 2021. [DOI: 10.3390/magnetochemistry7110143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Magnetic force microscopy (MFM) belongs to the methods that enable spatially resolved magnetization measurements on common thin-film samples or magnetic nanostructures. The lateral resolution can be much higher than in Kerr microscopy, another spatially resolved magnetization imaging technique, but since MFM commonly necessitates positioning a cantilever tip typically within a few nanometers from the surface, it is often more complicated than other techniques. Here, we investigate the progresses in MFM on magnetic nanofibers that can be found in the literature during the last years. While MFM measurements on magnetic nanodots or thin-film samples can often be found in the scientific literature, reports on magnetic force microscopy on single nanofibers or chaotic nanofiber mats are scarce. The aim of this review is to show which MFM investigations can be conducted on magnetic nanofibers, where the recent borders are, and which ideas can be transferred from MFM on other rough surfaces towards nanofiber mats.
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11
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Zamani Kouhpanji MR, Stadler BJH. Magnetic Nanowires for Nanobarcoding and Beyond. SENSORS (BASEL, SWITZERLAND) 2021; 21:4573. [PMID: 34283095 PMCID: PMC8271806 DOI: 10.3390/s21134573] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 06/26/2021] [Accepted: 07/01/2021] [Indexed: 12/15/2022]
Abstract
Multifunctional magnetic nanowires (MNWs) have been studied intensively over the last decades, in diverse applications. Numerous MNW-based systems have been introduced, initially for fundamental studies and later for sensing applications such as biolabeling and nanobarcoding. Remote sensing of MNWs for authentication and/or anti-counterfeiting is not only limited to engineering their properties, but also requires reliable sensing and decoding platforms. We review the latest progress in designing MNWs that have been, and are being, introduced as nanobarcodes, along with the pros and cons of the proposed sensing and decoding methods. Based on our review, we determine fundamental challenges and suggest future directions for research that will unleash the full potential of MNWs for nanobarcoding applications.
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Affiliation(s)
- Mohammad Reza Zamani Kouhpanji
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA;
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Bethanie J. H. Stadler
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA;
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