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Maltoni P, Barucca G, Rutkowski B, Spadaro MC, Jönsson PE, Varvaro G, Yaacoub N, De Toro JA, Peddis D, Mathieu R. Unraveling Exchange Coupling in Ferrites Nano-Heterostructures. Small 2024; 20:e2304152. [PMID: 37888807 DOI: 10.1002/smll.202304152] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 10/10/2023] [Indexed: 10/28/2023]
Abstract
The magnetic coupling of a set of SrFe12 O19 /CoFe2 O4 nanocomposites is investigated. Advanced electron microscopy evidences the structural coherence and texture at the interfaces of the nanostructures. The fraction of the lower anisotropy phase (CoFe2 O4 ) is tuned to assess the limits that define magnetically exchange-coupled interfaces by performing magnetic remanence, first-order reversal curves (FORCs), and relaxation measurements. By combining these magnetometry techniques and the structural and morphological information from X-ray diffraction, electron microscopy, and Mössbauer spectrometry, the exchange intergranular interaction is evidenced, and the critical thickness within which coupled interfaces have a uniform reversal unraveled.
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Affiliation(s)
- Pierfrancesco Maltoni
- Department of Materials Science and Engineering, Uppsala University, Box 35, Uppsala, 751 03, Sweden
| | - Gianni Barucca
- Dipartimento di Scienze e Ingegneria della Materia dell'Ambiente ed Urbanistica-SIMAU, Università Politecnica delle Marche, Ancona, 60131, Italy
| | - Bogdan Rutkowski
- Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Al. A. Mickiewicza 30, Kraków, 30-059, Poland
| | - Maria Chiara Spadaro
- Dipartimento di Scienze e Ingegneria della Materia dell'Ambiente ed Urbanistica-SIMAU, Università Politecnica delle Marche, Ancona, 60131, Italy
| | - Petra E Jönsson
- Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala, SE-751 20, Sweden
| | - Gaspare Varvaro
- Istituto di Struttura della Materia, nM2-lab, Consiglio Nazionale delle Ricerche, Monterotondo Scalo, Rome, 00015, Italy
| | - Nader Yaacoub
- Institut des Molécules et Matériaux du Mans, CNRS UMR-6283, Le Mans Université, Le Mans, F-72085, France
| | - José A De Toro
- Instituto Regional de Investigación Científica Aplicada (IRICA) and Departamento de Física Aplicada, Universidad de Castilla-La Mancha, Ciudad Real, 13071, Spain
| | - Davide Peddis
- Istituto di Struttura della Materia, nM2-lab, Consiglio Nazionale delle Ricerche, Monterotondo Scalo, Rome, 00015, Italy
- Dipartimento di Chimica e Chimica Industriale & INSTM, nM2-Lab, Università degli Studi di Genova, Via Dodecaneso 31, Genova, 1-16146, Italy
| | - Roland Mathieu
- Department of Materials Science and Engineering, Uppsala University, Box 35, Uppsala, 751 03, Sweden
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Hassan M, Koraltan S, Ullrich A, Bruckner F, Serha RO, Levchenko KV, Varvaro G, Kiselev NS, Heigl M, Abert C, Suess D, Albrecht M. Dipolar skyrmions and antiskyrmions of arbitrary topological charge at room temperature. Nat Phys 2024; 20:615-622. [PMID: 38638455 PMCID: PMC11021192 DOI: 10.1038/s41567-023-02358-z] [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] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 11/29/2023] [Indexed: 04/20/2024]
Abstract
Magnetic skyrmions are localized, stable topological magnetic textures that can move and interact with each other like ordinary particles when an external stimulus is applied. The efficient control of the motion of spin textures using spin-polarized currents opened an opportunity for skyrmionic devices such as racetrack memory and neuromorphic or reservoir computing. The coexistence of skyrmions with high topological charge in the same system promises further possibilities for efficient technological applications. In this work, we directly observe dipolar skyrmions and antiskyrmions with arbitrary topological charge in Co/Ni multilayers at room temperature. We explore the dipolar-stabilized spin objects with topological charges of up to 10 and characterize their nucleation process, their energy dependence on the topological charge and the effect of the material parameters on their stability. Furthermore, our micromagnetic simulations demonstrate spin-transfer-induced motion of these spin objects, which is important for their potential device application.
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Affiliation(s)
- Mariam Hassan
- Institute of Physics, University of Augsburg, Augsburg, Germany
- ISM – CNR, nM2-Lab, Monterotondo Scalo, Roma, Italy
| | - Sabri Koraltan
- Physics of Functional Materials, Faculty of Physics, University of Vienna, Vienna, Austria
- Vienna Doctoral School in Physics, University of Vienna, Vienna, Austria
- Research Platform MMM Mathematics – Magnetism – Materials, University of Vienna, Vienna, Austria
| | - Aladin Ullrich
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | - Florian Bruckner
- Physics of Functional Materials, Faculty of Physics, University of Vienna, Vienna, Austria
| | - Rostyslav O. Serha
- Vienna Doctoral School in Physics, University of Vienna, Vienna, Austria
- Nanomagnetism and Magnonics, Faculty of Physics, University of Vienna, Vienna, Austria
| | | | | | - Nikolai S. Kiselev
- Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, Jülich, Germany
| | - Michael Heigl
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | - Claas Abert
- Physics of Functional Materials, Faculty of Physics, University of Vienna, Vienna, Austria
- Research Platform MMM Mathematics – Magnetism – Materials, University of Vienna, Vienna, Austria
| | - Dieter Suess
- Physics of Functional Materials, Faculty of Physics, University of Vienna, Vienna, Austria
- Research Platform MMM Mathematics – Magnetism – Materials, University of Vienna, Vienna, Austria
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Hassan M, Laureti S, Rinaldi C, Fagiani F, Barucca G, Casoli F, Mezzi A, Bolli E, Kaciulis S, Fix M, Ullrich A, Albrecht M, Varvaro G. Thin-Film Heterostructures Based on Co/Ni Synthetic Antiferromagnets on Polymer Tapes: Toward Sustainable Flexible Spintronics. ACS Appl Mater Interfaces 2022; 14:51496-51509. [PMID: 36318544 DOI: 10.1021/acsami.2c14000] [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] [Indexed: 06/16/2023]
Abstract
Synthetic antiferromagnets with perpendicular magnetic anisotropy (PMA-SAFs) have gained growing attention for both conventional and next-generation spin-based technologies. While the progress of PMA-SAF spintronic devices on rigid substrates has been remarkable, only few examples of flexible thin-film heterostructures are reported in the literature, all containing platinum group metals (PGMs). Systems based on Co/Ni may offer additional advantages with respect to devices containing PGMs, i.e., low damping and high spin polarization. Moreover, limiting the use of PGMs may relieve the demand for critical raw materials and reduce the environmental impact of related technologies, thus contributing to the transition toward a more sustainable future. Here, we discuss for the first time the realization of Co/Ni-based PMA-SAFs on polymer tapes and exploit it to obtain flexible giant magneto-resistive spin valves (GMR-SVs) with perpendicular magnetic anisotropy. Several combinations of buffer and capping layers (i.e., Pt, Pd, and Cu/Ta) are also investigated. High-quality flexible SAFs with a fully compensated antiferromagnetic region and SVs with a sizable GMR ratio (up to 4.4%), in line with the values reported in the literature for similar systems on rigid substrates, were obtained in all cases. However, we demonstrate that PGMs allows achieving the best results when used as a buffer layer, while Cu is the best choice as a capping layer to optimize the properties of the stacks. We justify the role of buffer and capping layers in terms of different interdiffusion mechanisms occurring at the interface between the metallic layers. These results, along with the high robustness of the samples' properties against bending (up to 180°), indicate that complex and bendable Co/Ni-based heterostructures with reduced content of PGMs can be obtained on flexible tapes, allowing for the development of novel flexible and sustainable spintronic devices for applications in many fields including wearable electronics, soft robotics, and biomedicine.
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Affiliation(s)
- Mariam Hassan
- ISM-CNR, nM2-Lab, Area della Ricerca Roma 1, Monterotondo Scalo (Roma)00015, Italy
- Institute of Physics, University of Augsburg, Universitätsstraße 1 Nord, D-86159Augsburg, Germany
| | - Sara Laureti
- ISM-CNR, nM2-Lab, Area della Ricerca Roma 1, Monterotondo Scalo (Roma)00015, Italy
| | - Christian Rinaldi
- Department of Physics, Politecnico di Milano, via G. Colombo 81, Milano20133, Italy
| | - Federico Fagiani
- Department of Physics, Politecnico di Milano, via G. Colombo 81, Milano20133, Italy
| | - Gianni Barucca
- Department SIMAU, University Politecnica delle Marche, via Brecce Bianche, Ancona60131, Italy
| | | | - Alessio Mezzi
- ISMN-CNR, Area della Ricerca Roma 1, Monterotondo Scalo (Roma)00015, Italy
| | - Eleonora Bolli
- ISMN-CNR, Area della Ricerca Roma 1, Monterotondo Scalo (Roma)00015, Italy
| | - Saulius Kaciulis
- ISMN-CNR, Area della Ricerca Roma 1, Monterotondo Scalo (Roma)00015, Italy
| | - Mario Fix
- Institute of Physics, University of Augsburg, Universitätsstraße 1 Nord, D-86159Augsburg, Germany
| | - Aladin Ullrich
- Institute of Physics, University of Augsburg, Universitätsstraße 1 Nord, D-86159Augsburg, Germany
| | - Manfred Albrecht
- Institute of Physics, University of Augsburg, Universitätsstraße 1 Nord, D-86159Augsburg, Germany
| | - Gaspare Varvaro
- ISM-CNR, nM2-Lab, Area della Ricerca Roma 1, Monterotondo Scalo (Roma)00015, Italy
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Falciglia PP, Gagliano E, Scandura P, Bianco C, Tosco T, Sethi R, Varvaro G, Agostinelli E, Bongiorno C, Russo A, Romano S, Malandrino G, Roccaro P, Vagliasindi FG. Physico-magnetic properties and dynamics of magnetite (Fe3O4) nanoparticles (MNPs) under the effect of permanent magnetic fields in contaminated water treatment applications. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.121342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Verna A, Alippi P, Offi F, Barucca G, Varvaro G, Agostinelli E, Albrecht M, Rutkowski B, Ruocco A, Paoloni D, Valvidares M, Laureti S. Correction to "Disclosing the Nature of Asymmetric Interface Magnetism in Co/Pt Multilayers". ACS Appl Mater Interfaces 2022; 14:24069-24069. [PMID: 35544701 DOI: 10.1021/acsami.2c06943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
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Verna A, Alippi P, Offi F, Barucca G, Varvaro G, Agostinelli E, Albrecht M, Rutkowski B, Ruocco A, Paoloni D, Valvidares M, Laureti S. Disclosing the Nature of Asymmetric Interface Magnetism in Co/Pt Multilayers. ACS Appl Mater Interfaces 2022; 14:12766-12776. [PMID: 35254812 DOI: 10.1021/acsami.1c22341] [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] [Indexed: 06/14/2023]
Abstract
Nowadays, a wide number of applications based on magnetic materials rely on the properties arising at the interface between different layers in complex heterostructures engineered at the nanoscale. In ferromagnetic/heavy metal multilayers, such as the [Co/Pt]N and [Co/Pd]N systems, the magnetic proximity effect was demonstrated to be asymmetric, thus inducing a magnetic moment on the Pt (Pd) layer that is typically higher at the top Co/Pt(Pd) interface. In this work, advanced spectroscopic and imaging techniques were combined with theoretical approaches to clarify the origin of this asymmetry both in Co/Pt trilayers and, for the first time, in multilayer systems that are more relevant for practical applications. The different magnetic moment induced at the Co/Pt interfaces was correlated to the microstructural features that are in turn affected by the growth processes that induce a different intermixing during the film deposition, thus influencing the interface magnetic profile.
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Affiliation(s)
- Adriano Verna
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, Roma I-00146, Italy
- ENEA-FSN-Fiss-SNI, Casaccia R. C., Via Anguillarese 301, Roma 00123, Italy
| | - Paola Alippi
- Istituto di Struttura della Materia, CNR, Monterotondo Scalo, Roma 00015, Italy
| | - Francesco Offi
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, Roma I-00146, Italy
| | - Gianni Barucca
- Dipartimento SIMAU, Università Politecnica Delle Marche, Via Brecce Bianche, Ancona 60121, Italy
| | - Gaspare Varvaro
- Istituto di Struttura della Materia, CNR, nM2-Lab, Monterotondo Scalo, Roma 00015, Italy
| | - Elisabetta Agostinelli
- Istituto di Struttura della Materia, CNR, nM2-Lab, Monterotondo Scalo, Roma 00015, Italy
| | - Manfred Albrecht
- Institute of Physics, University of Augsburg, Universitätsstraße 1 Nord, Augsburg D-86159, Germany
| | - Bogdan Rutkowski
- Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Al. A. Mickiewicza 30, Kraków 30-059, Poland
| | - Alessandro Ruocco
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, Roma I-00146, Italy
| | - Daniele Paoloni
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, Roma I-00146, Italy
| | - Manuel Valvidares
- ALBA Synchrotron Light Source, Cerdanyola del Vallès, Barcelona E-08290, Spain
| | - Sara Laureti
- Istituto di Struttura della Materia, CNR, nM2-Lab, Monterotondo Scalo, Roma 00015, Italy
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Fiore AM, Varvaro G, Agostinelli E, Mangone A, De Giglio E, Terzano R, Allegretta I, Dell'Anna MM, Fiore S, Mastrorilli P. Synthesis and Use in Catalysis of Hematite Nanoparticles Obtained from a Polymer Supported Fe(III) Complex. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202100943] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Ambra M. Fiore
- DICATECh Department Politecnico di Bari Via Orabona, 4. 70125 Bari Italy
| | - Gaspare Varvaro
- Istituto di Struttura della Materia Consiglio Nazionale delle Ricerche Research Area Roma 1, Monterotondo Scalo 00016 Roma Italy
| | - Elisabetta Agostinelli
- Istituto di Struttura della Materia Consiglio Nazionale delle Ricerche Research Area Roma 1, Monterotondo Scalo 00016 Roma Italy
| | - Annarosa Mangone
- Dipartimento di Chimica Università degli Studi di Bari-Aldo Moro Via Orabona, 4 70125 Bari Italy
| | - Elvira De Giglio
- Dipartimento di Chimica Università degli Studi di Bari-Aldo Moro Via Orabona, 4 70125 Bari Italy
| | - Roberto Terzano
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti Università degli Studi di Bari-Aldo Moro Via Amendola, 165/A 70125 Bari Italy
| | - Ignazio Allegretta
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti Università degli Studi di Bari-Aldo Moro Via Amendola, 165/A 70125 Bari Italy
| | | | - Saverio Fiore
- Institute of Methodologies for Environmental Analysis National Research Council of Italy (IMAA-CNR) Tito Scalo 85050 Potenza Italy
| | - Piero Mastrorilli
- DICATECh Department Politecnico di Bari Via Orabona, 4. 70125 Bari Italy
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8
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Maltoni P, Ivanov SA, Barucca G, Varvaro G, Peddis D, Mathieu R. Complex correlations between microstructure and magnetic behavior in SrFe 12O 19 hexaferrite nanoparticles. Sci Rep 2021; 11:23307. [PMID: 34857873 PMCID: PMC8639738 DOI: 10.1038/s41598-021-02782-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [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: 10/02/2021] [Accepted: 11/22/2021] [Indexed: 12/03/2022] Open
Abstract
The magnetic properties of SrFe12O19 (SFO) hard hexaferrites are governed by the complex relation to its microstructure, determining their relevance for permanent magnets´ applications. A set of SFO nanoparticles obtained by sol–gel self-combustion synthesis was selected for an in-depth structural X-Rays powder diffraction (XRPD) characterization by means of G(L) line-profile analysis. The obtained crystallites´ size distribution reveal a clear dependence of the size along the [001] direction on the synthesis approach, resulting in the formation of platelet-like crystallites. In addition, the size of the SFO nanoparticles was determined by transmission electron microscopy (TEM) analysis and the average number of crystallites within a particle was estimated. These results have been evaluated to illustrate the formation of single-domain state below a critical value, and the activation volume was derived from time dependent magnetization measurements, aiming to clarify the reversal magnetization process of hard magnetic materials.
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Affiliation(s)
- Pierfrancesco Maltoni
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03, Uppsala, Sweden.
| | - Sergey A Ivanov
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03, Uppsala, Sweden.,Department of Chemistry, M.V. Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow, Russia, 119991
| | - Gianni Barucca
- Department SIMAU, Università Politecnica delle Marche, Via Brecce Bianche 12, 60131, Ancona, Italy
| | - Gaspare Varvaro
- Istituto di Struttura della Materia-CNR, nM2-Lab, 00015, Monterotondo Scalo, RM, Italy
| | - Davide Peddis
- Istituto di Struttura della Materia-CNR, nM2-Lab, 00015, Monterotondo Scalo, RM, Italy.,Department of Chemistry and Industrial Chemistry, nM2-Lab, Università degli Studi di Genova, Via Dodecaneso 31, 1-16146, Genova, Italy
| | - Roland Mathieu
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03, Uppsala, Sweden.
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Hassan M, Laureti S, Rinaldi C, Fagiani F, Varotto S, Barucca G, Schmidt NY, Varvaro G, Albrecht M. Perpendicularly magnetized Co/Pd-based magneto-resistive heterostructures on flexible substrates. Nanoscale Adv 2021; 3:3076-3084. [PMID: 36133649 PMCID: PMC9418425 DOI: 10.1039/d1na00110h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/08/2021] [Indexed: 06/14/2023]
Abstract
Flexible magneto-resistive heterostructures have received a great deal of attention over the past few years as they allow for new product paradigms that are not possible with conventional rigid substrates. While the progress and development of systems with longitudinal magnetic anisotropy on non-planar substrates has been remarkable, flexible magneto-resistive heterostructures with perpendicular magnetic anisotropy (PMA) have never been studied despite the possibility to obtain additional functionality and improved performance. To fill this gap, flexible PMA Co/Pd-based giant magneto-resistive (GMR) spin-valve stacks were prepared by using an innovative transfer-and-bonding strategy exploiting the low adhesion of a gold underlayer to SiO x /Si(100) substrates. The approach allows overcoming the limits of the direct deposition on commonly used polymer substrates, whose high surface roughness and low melting temperature could hinder the growth of complex heterostructures with perpendicular magnetic anisotropy. The obtained PMA flexible spin-valves show a sizeable GMR ratio (∼1.5%), which is not affected by the transfer process, and a high robustness against bending as indicated by the slight change of the magneto-resistive properties upon bending, thus allowing for their integration on curved surfaces and the development of a novel class of advanced devices based on flexible magneto-resistive structures with perpendicular magnetic anisotropy. Besides endowing the family of flexible electronics with PMA magneto-resistive heterostructures, the exploitation of the results might apply to high temperature growth processes and to the fabrication of other functional and flexible multilayer materials engineered at the nanoscale.
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Affiliation(s)
- M Hassan
- Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia, nM2-Lab Via Salaria km 29.300 Monterotondo Scalo (Roma) 00015 Italy
- Università Politecnica delle Marche, Dipartimento SIMAU Via Brecce Bianche Ancona 60131 Italy
| | - S Laureti
- Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia, nM2-Lab Via Salaria km 29.300 Monterotondo Scalo (Roma) 00015 Italy
| | - C Rinaldi
- Politecnico di Milano, Department of Physics and IFN-CNR via G. Colombo 81 20133 Milano Italy
| | - F Fagiani
- Politecnico di Milano, Department of Physics and IFN-CNR via G. Colombo 81 20133 Milano Italy
| | - S Varotto
- Politecnico di Milano, Department of Physics and IFN-CNR via G. Colombo 81 20133 Milano Italy
| | - G Barucca
- Università Politecnica delle Marche, Dipartimento SIMAU Via Brecce Bianche Ancona 60131 Italy
| | - N Y Schmidt
- University of Augsburg, Institute of Physics Universitätsstraße 1 Nord D-86159 Augsburg Germany
| | - G Varvaro
- Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia, nM2-Lab Via Salaria km 29.300 Monterotondo Scalo (Roma) 00015 Italy
| | - M Albrecht
- University of Augsburg, Institute of Physics Universitätsstraße 1 Nord D-86159 Augsburg Germany
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Laureti S, Gerardino A, D'Acapito F, Peddis D, Varvaro G. The role of chemical and microstructural inhomogeneities on interface magnetism. Nanotechnology 2021; 32:205701. [PMID: 33530067 DOI: 10.1088/1361-6528/abe260] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The study of interfacing effects arising when different magnetic phases are in close contact has led to the discovery of novel physical properties and the development of innovative technological applications of nanostructured magnetic materials. Chemical and microstructural inhomogeneities at the interfacial region, driven by interdiffusion processes, chemical reactions and interface roughness may significantly affect the final properties of a material and, if suitably controlled, may represent an additional tool to finely tune the overall physical properties. The activity at the Nanostructured Magnetic Materials Laboratory (nM2-Lab) at CNR-ISM of Italy is aimed at designing and investigating nanoscale-engineered magnetic materials, where the overall magnetic properties are dominated by the interface exchange coupling. In this review, some examples of recent studies where the chemical and microstructural properties are critical in determining the overall magnetic properties in core/shell nanoparticles, nanocomposites and multilayer heterostructures are presented.
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Affiliation(s)
- S Laureti
- Istituto di Struttura della Materia, CNR, nM2-Lab, Monterotondo Scalo (Roma), I-00015, Italy
| | - A Gerardino
- Istituto di Fotonica e Nanotecnologie, CNR, via Cineto Romano 42, I-00156, Italy
| | - F D'Acapito
- CNR-IOM-OGG c/o ESRF, LISA CRG, c/o ESRF BP220, F-38043 Grenoble, France
| | - D Peddis
- Istituto di Struttura della Materia, CNR, nM2-Lab, Monterotondo Scalo (Roma), I-00015, Italy
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, nM2-Lab, Via Dodecaneso 31, Genova, I-16146, Italy
| | - G Varvaro
- Istituto di Struttura della Materia, CNR, nM2-Lab, Monterotondo Scalo (Roma), I-00015, Italy
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11
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Belviso C, Peddis D, Varvaro G, Abdolrahimi M, Reverberi AP, Cavalcante F. Obsidian as a Raw Material for Eco-Friendly Synthesis of Magnetic Zeolites. Materials (Basel) 2020; 13:ma13204633. [PMID: 33081399 PMCID: PMC7603046 DOI: 10.3390/ma13204633] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/13/2020] [Accepted: 10/15/2020] [Indexed: 06/11/2023]
Abstract
A sample of rhyolitic obsidian (OS) was used as raw material for zeolite synthesis by long (4 days) and fast (2 h)-aging hydrothermal processes. Zeolite synthesis was also performed by a fast (2 h) sonication method. The products were analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) both immediately after and 3 years after their formation in order to determine the stability of synthetic materials according to the method used. The results confirm zeolitization of obsidian both by long-aging conventional hydrothermal heating and fast hydrothermal process. However, the data highlight the efficiency of direct ultrasound energy in achieving more stable zeolite crystals over time. These results carried out using a natural source, follow those already obtained using wastes and pure sources as raw materials thus providing a definitive validation of the different mechanisms controlling zeolite formation according to the process used. Moreover, the results confirm the effectiveness of ultrasonic energy in the formation of zeolites that are more stable over time. Due to the chemical composition of the obsidian precursor, all synthetic zeolites show good magnetic properties (i.e., saturation magnetization), in view to potential magnetic separation.
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Affiliation(s)
- Claudia Belviso
- Istituto di Metodologie per l’Analisi Ambientale—CNR, 85050 Tito Scalo, Italy;
| | - Davide Peddis
- Departments of Chemistry and Industrial Chemistry (DCIC), Università of Genova, 16146 Genova, Italy; (D.P.); (A.P.R.)
- Istituto di Struttura della Materia—CNR, 00015 Monterotondo Scalo, Italy;
| | - Gaspare Varvaro
- Dipartimento di Scienze, Università degli Studi Roma Tre, 00146 Roma, Italy;
| | - Maryam Abdolrahimi
- Istituto di Struttura della Materia—CNR, 00015 Monterotondo Scalo, Italy;
- Dipartimento di Scienze, Università degli Studi Roma Tre, 00146 Roma, Italy;
| | - Andrea Pietro Reverberi
- Departments of Chemistry and Industrial Chemistry (DCIC), Università of Genova, 16146 Genova, Italy; (D.P.); (A.P.R.)
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Varvaro G, Agostinelli E, Laureti S. A Special Section on Metastable, Amorphous and Nanostructured Materials. J Nanosci Nanotechnol 2020; 20:4537-4539. [PMID: 31968515 DOI: 10.1166/jnn.2020.17864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Affiliation(s)
- Gaspare Varvaro
- National Research Council Institute of Structure of Matter Roma (Italy)
| | | | - Sara Laureti
- National Research Council Institute of Structure of Matter Roma (Italy)
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Sayed F, Kotnana G, Muscas G, Locardi F, Comite A, Varvaro G, Peddis D, Barucca G, Mathieu R, Sarkar T. Symbiotic, low-temperature, and scalable synthesis of bi-magnetic complex oxide nanocomposites. Nanoscale Adv 2020; 2:851-859. [PMID: 36133229 PMCID: PMC9417494 DOI: 10.1039/c9na00619b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 01/15/2020] [Indexed: 06/12/2023]
Abstract
Functional oxide nanocomposites, where the individual components belong to the family of strongly correlated electron oxides, are an important class of materials, with potential applications in several areas such as spintronics and energy devices. For these materials to be technologically relevant, it is essential to design low-cost and scalable synthesis techniques. In this work, we report a low-temperature and scalable synthesis of prototypical bi-magnetic LaFeO3-CoFe2O4 nanocomposites using a unique sol-based synthesis route, where both the phases of the nanocomposite are formed during the same time. In this bottom-up approach, the heat of formation of one phase (CoFe2O4) allows the crystallization of the second phase (LaFeO3), and completely eliminates the need for conventional high-temperature annealing. A symbiotic effect is observed, as the second phase reduces grain growth of the first phase, thus yielding samples with lower particle sizes. Through thermogravimetric, structural, and morphological studies, we have confirmed the reaction mechanism. The magnetic properties of the bi-magnetic nanocomposites are studied, and reveal a distinct effect of the synthesis conditions on the coercivity of the particles. Our work presents a basic concept of significantly reducing the synthesis temperature of bi-phasic nanocomposites (and thus also the synthesis cost) by using one phase as nucleation sites for the second one, as well as using the heat of formation of one phase to crystallize the other.
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Affiliation(s)
- F Sayed
- Department of Materials Science and Engineering, Uppsala University Box 534 SE-75121 Uppsala Sweden
| | - G Kotnana
- Department of Materials Science and Engineering, Uppsala University Box 534 SE-75121 Uppsala Sweden
| | - G Muscas
- Department of Physics and Astronomy, Uppsala University Box 516 SE-75120 Uppsala Sweden
| | - F Locardi
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova Via Dodecaneso 31 Genova 16146 Italy
- Physics and Chemistry of Nanostructures (PCN), Ghent University Krijgslaan 281-S3 B9000 Gent Belgium
| | - A Comite
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova Via Dodecaneso 31 Genova 16146 Italy
| | - G Varvaro
- Istituto di Struttura della Materia - CNR Area della Ricerca di Roma1, Monterotondo Scalo RM 00015 Italy
| | - D Peddis
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova Via Dodecaneso 31 Genova 16146 Italy
- Istituto di Struttura della Materia - CNR Area della Ricerca di Roma1, Monterotondo Scalo RM 00015 Italy
| | - G Barucca
- Department SIMAU, University Politecnica delle Marche Via Brecce Bianche Ancona 60131 Italy
| | - R Mathieu
- Department of Materials Science and Engineering, Uppsala University Box 534 SE-75121 Uppsala Sweden
| | - T Sarkar
- Department of Materials Science and Engineering, Uppsala University Box 534 SE-75121 Uppsala Sweden
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14
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Varvaro G, Laureti S, Peddis D, Hassan M, Barucca G, Mengucci P, Gerardino A, Giovine E, Lik O, Nissen D, Albrecht M. Co/Pd-Based synthetic antiferromagnetic thin films on Au/resist underlayers: towards biomedical applications. Nanoscale 2019; 11:21891-21899. [PMID: 31701115 DOI: 10.1039/c9nr06866j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Thin film stacks consisting of multiple repeats M of synthetic antiferromagnetic (SAF) [Co/Pd]N/Ru/[Co/Pd]N units with perpendicular magnetic anisotropy were explored as potential starting materials to fabricate free-standing micro/nanodisks, which represent a promising candidate system for theranostic applications. The films were directly grown on a sacrificial resist layer spin-coated on SiOx/Si(100) substrates, required for the preparation of free-standing disks after its dissolution. Furthermore, the film stack was sandwiched between two Au layers to allow further bio-functionalization. For M ≤ 5, the samples fulfill all the key criteria mandatory for biomedical applications, i.e., zero remanence, zero field susceptibility at small fields and sharp switching to saturation, together with the ability to vary the total magnetic moment at saturation by changing the number of repetitions of the multi-stack. Moreover, the samples show strong perpendicular magnetic anisotropy, which is required for applications relying on the transduction of a mechanical force through the micro/nano-disks under a magnetic field, such as the mechanical cell disruption, which is nowadays considered a promising alternative to the more investigated magnetic hyperthermia approach for cancer treatment. In a further step, SAF microdisks were prepared from the continuous multi-stacks by combining electron beam lithography and Ar ion milling, revealing similar magnetic properties as compared to the continuous films.
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Affiliation(s)
- G Varvaro
- Istituto di Struttura della Materia, CNR, Via Salaria km 29.300, Monterotondo Scalo, Roma, 00015, Italy.
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15
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Sayed F, Muscas G, Jovanovic S, Barucca G, Locardi F, Varvaro G, Peddis D, Mathieu R, Sarkar T. Controlling magnetic coupling in bi-magnetic nanocomposites. Nanoscale 2019; 11:14256-14265. [PMID: 31318002 DOI: 10.1039/c9nr05364f] [Citation(s) in RCA: 1] [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] [Indexed: 06/10/2023]
Abstract
Magnetic nanocomposites constitute a vital class of technologically relevant materials, in particular for next-generation applications ranging from biomedicine, catalysis, and energy devices. Key to designing such materials is determining and controlling the extent of magnetic coupling in them. In this work, we show how the magnetic coupling in bi-magnetic nanocomposites can be controlled by the growth technique. Using four different synthesis strategies to prepare prototypical LaFeO3-CoFe2O4 and LaFeO3-Co0.5Zn0.5Fe2O4 nanocomposite systems, and by performing comprehensive magnetic measurements, we demonstrate that the final material exhibits striking differences in their magnetic coupling that is distinct to the growth method. Through structural and morphological studies, we confirm the link between the magnetic coupling and growth methods due to distinct levels of particle agglomeration at the very microscopic scale. Our studies reveal an inverse relationship between the strength of magnetic coupling and the degree of particle agglomeration in the nanocomposites. Our work presents a basic concept of controlling the particle agglomeration to tune magnetic coupling, relevant for designing advanced bi-magnetic nanocomposites for novel applications.
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Affiliation(s)
- F Sayed
- Department of Engineering Sciences, Uppsala University, Box 534, SE-75121 Uppsala, Sweden.
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16
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Sarkar T, Muscas G, Barucca G, Locardi F, Varvaro G, Peddis D, Mathieu R. Tunable single-phase magnetic behavior in chemically synthesized AFeO 3-MFe 2O 4 (A = Bi or La, M = Co or Ni) nanocomposites. Nanoscale 2018; 10:22990-23000. [PMID: 30500041 DOI: 10.1039/c8nr06922k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The properties of magnetic nanocomposites rely strongly on the interplay between those of the constituent components. When the individual components themselves are complex systems belonging to the family of correlated electron oxide systems which typically exhibit exotic physical properties, it becomes nontrivial to customize the properties of the nanocomposite. In this paper, we demonstrate an easy, but effective method to synthesize and tune the magnetic properties of nanocomposites consisting of correlated electron oxide systems as the individual components. Our method is based on a novel synthesis technique by which the two components of the nanocomposite can be directly integrated with each other, yielding homogeneous samples on the nanoscale with magnetic behavior reminiscent of a single phase. We illustrate our method using multiferroic BiFeO3 (BFO) and LaFeO3 (LFO) as the major phase (i.e., matrix), and MFe2O4 (M = Co2+ or Ni2+) as the embedded magnetic phase. Furthermore, we show that by a proper selection of the second phase in the nanocomposite, it is possible to customize the magnetic properties of the matrix. We illustrate this by choosing CoFe2O4 and NiFe2O4, two oxides with widely differing magnetic anisotropies, as the embedded phase, and demonstrate that the coercivity of BFO and LFO can be increased or decreased depending on the choice of the embedded phase in the nanocomposite.
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Affiliation(s)
- T Sarkar
- Department of Engineering Sciences, Uppsala University, Box 534, SE-75121 Uppsala, Sweden.
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17
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Giannopoulos G, Barucca G, Kaidatzis A, Psycharis V, Salikhov R, Farle M, Koutsouflakis E, Niarchos D, Mehta A, Scuderi M, Nicotra G, Spinella C, Laureti S, Varvaro G. L1 0-FeNi films on Au-Cu-Ni buffer-layer: a high-throughput combinatorial study. Sci Rep 2018; 8:15919. [PMID: 30374113 PMCID: PMC6206008 DOI: 10.1038/s41598-018-34296-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [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: 01/24/2018] [Accepted: 10/12/2018] [Indexed: 11/25/2022] Open
Abstract
The fct L10-FeNi alloy is a promising candidate for the development of high performance critical-elements-free magnetic materials. Among the different materials, the Au-Cu-Ni alloy has resulted very promising; however, a detailed investigation of the effect of the buffer-layer composition on the formation of the hard FeNi phase is still missing. To accelerate the search of the best Au-Cu-Ni composition, a combinatorial approach based on High-Throughput (HT) experimental methods has been exploited in this paper. HT magnetic characterization methods revealed the presence of a hard magnetic phase with an out-of-plane easy-axis, whose coercivity increases from 0.49 kOe up to 1.30 kOe as the Au content of the Cu-Au-Ni buffer-layer decreases. Similarly, the out-of-plane magneto-crystalline anisotropy energy density increases from 0.12 to 0.35 MJ/m3. This anisotropy is attributed to the partial formation of the L10 FeNi phase induced by the buffer-layer. In the range of compositions we investigated, the buffer-layer structure does not change significantly and the modulation of the magnetic properties with the Au content in the combinatorial layer is mainly related to the different nature and extent of interlayer diffusion processes, which have a great impact on the formation and order degree of the L10 FeNi phase.
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Affiliation(s)
- G Giannopoulos
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, Athens, Greece.
| | - G Barucca
- Università Politecnica delle Marche, Dipartimento SIMAU, Via Brecce Bianche 12, Ancona, 60131, Italy.
| | - A Kaidatzis
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, Athens, Greece
| | - V Psycharis
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, Athens, Greece
| | - R Salikhov
- Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47057, Duisburg, Germany
- Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of RAS, 420029, Kazan, Russian Federation
| | - M Farle
- Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47057, Duisburg, Germany
- Center for Functionalized Magnetic Materials (FunMagMa), Immanuel Kant Baltic Federal University, Kaliningrad, Russian Federation
| | - E Koutsouflakis
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, Athens, Greece
| | - D Niarchos
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, Athens, Greece
| | - A Mehta
- SLAC National Accelerator Laboratory- Stanford University, Menlo Park, California, USA
| | - M Scuderi
- IMM-CNR, VII strada 5, 95121, Catania, Italy
| | - G Nicotra
- IMM-CNR, VII strada 5, 95121, Catania, Italy
| | - C Spinella
- IMM-CNR, VII strada 5, 95121, Catania, Italy
| | - S Laureti
- Istituto di Struttura della Materia, CNR, Monterotondo Scalo, Roma, Italy
| | - G Varvaro
- Istituto di Struttura della Materia, CNR, Monterotondo Scalo, Roma, Italy
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Di Trolio A, Alippi P, Bauer EM, Ciatto G, Chu MH, Varvaro G, Polimeni A, Capizzi M, Valentini M, Bobba F, Di Giorgio C, Amore Bonapasta A. Ferromagnetism and Conductivity in Hydrogen Irradiated Co-Doped ZnO Thin Films. ACS Appl Mater Interfaces 2016; 8:12925-12931. [PMID: 27123761 DOI: 10.1021/acsami.6b04203] [Citation(s) in RCA: 4] [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] [Indexed: 06/05/2023]
Abstract
Impressive changes in the transport and ferromagnetic properties of Co-doped ZnO thin films have been obtained by postgrowth hydrogen irradiation at temperatures of 400 °C. Hydrogen incorporation increases the saturation magnetization by one order of magnitude (up to ∼1.50 μB/Co) and increases the carrier density and mobility by about a factor of two. In addition to the magnetic characterization, the transport and structural properties of hydrogenated ZnO:Co have been investigated by Hall effect, local probe conductivity measurements, micro-Raman, and X-ray absorption spectroscopy. Particular care has been given to the detection of Co oxides and metal Co nanophases, whose influence on the increase in the transport and ferromagnetic properties can be excluded on the ground of the achieved results. The enhancement in ferromagnetism is directly related to the dose of H introduced in the samples. On the contrary, despite the shallow donor character of H atoms, the increase in carrier density n is not related to the H dose. These apparently contradictory effects of H are fully accounted for by a mechanism based on a theoretical model involving Co-VO (Co-O vacancy) pairs.
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Affiliation(s)
- A Di Trolio
- CNR-Istituto dei Sistemi Complessi, U.O.S. di Tor Vergata , Via del Fosso del Cavaliere 100, 00133 Roma, Italy
- Laboratori Nazionali di Frascati, INFN , Via E. Fermi 27, Frascati, RM 00044, Italy
| | - P Alippi
- CNR-Istituto di Struttura della Materia, Via Salaria Km. 29,300, 00015 Monterotondo, Scalo, Italy
| | - E M Bauer
- CNR-Istituto di Struttura della Materia, Via Salaria Km. 29,300, 00015 Monterotondo, Scalo, Italy
| | - G Ciatto
- Synchrotron Soleil, L'Orme des merisiers, Saint-Aubin, BP48, 91192 Gif-sur Yvette, Cedex, France
| | - M H Chu
- Synchrotron Soleil, L'Orme des merisiers, Saint-Aubin, BP48, 91192 Gif-sur Yvette, Cedex, France
| | - G Varvaro
- CNR-Istituto di Struttura della Materia, Via Salaria Km. 29,300, 00015 Monterotondo, Scalo, Italy
| | - A Polimeni
- Dipartimento di Fisica, Sapienza Universitá di Roma , P.le A. Moro 2, 00185 Roma, Italy
| | - M Capizzi
- Dipartimento di Fisica, Sapienza Universitá di Roma , P.le A. Moro 2, 00185 Roma, Italy
| | - M Valentini
- Dipartimento di Fisica, Sapienza Universitá di Roma , P.le A. Moro 2, 00185 Roma, Italy
- Casaccia Research Center, ENEA , via Anguillarese 301, 00060 Roma, Italy
| | - F Bobba
- Dipartimento di Fisica, Universitá di Salerno , Via Giovanni Paolo II, Fisciano, SA 84084, Italy
| | - C Di Giorgio
- Dipartimento di Fisica, Universitá di Salerno , Via Giovanni Paolo II, Fisciano, SA 84084, Italy
| | - A Amore Bonapasta
- CNR-Istituto di Struttura della Materia, Via Salaria Km. 29,300, 00015 Monterotondo, Scalo, Italy
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Muscas G, Anil Kumar P, Barucca G, Concas G, Varvaro G, Mathieu R, Peddis D. Designing new ferrite/manganite nanocomposites. Nanoscale 2016; 8:2081-2089. [PMID: 26697925 DOI: 10.1039/c5nr07572f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Two kinds of nanocomposites of transition metal oxides were synthesized and investigated. Each nanocomposite comprises nanoparticles of La0.67Ca0.33MnO3 and CoFe2O4 in similar volume fractions, however arranged with different morphologies. The temperature-dependent magnetic and electrical properties of the two systems are found to greatly differ, suggesting different degrees of interaction and coupling of their constituents. This is confirmed by magnetic field-dependent experiments, which reveal contrasted magnetization reversal and magnetoresistance in the systems. We discuss this morphology-physical property relationship, and the possibility to further tune the magnetism and magneto-transport in such nanocomposites.
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Affiliation(s)
- G Muscas
- Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21, Uppsala, Sweden. and Istituto di Struttura della Materia - CNR, 00015 Monterotondo Scalo (RM), Italy.
| | - P Anil Kumar
- Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21, Uppsala, Sweden.
| | - G Barucca
- Dipartimento di Scienze e Ingegneria della Materia, dell'Ambiente ed Urbanistica, Università Politecnica delle Marche, via Brecce Bianche 12, Ancona, Italy
| | - G Concas
- Dipartimento di Fisica, Università di Cagliari, S.P. Monserrato-Sestu km 0.700, 09042, Monserrato, Italy
| | - G Varvaro
- Istituto di Struttura della Materia - CNR, 00015 Monterotondo Scalo (RM), Italy.
| | - R Mathieu
- Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21, Uppsala, Sweden.
| | - D Peddis
- Istituto di Struttura della Materia - CNR, 00015 Monterotondo Scalo (RM), Italy.
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Peddis D, Muscas G, Mathieu R, Kumar PA, Varvaro G, Singh G, Orue I, Gil-Carton D, Marcano L, Muela A, Fdez-Gubieda ML. Studying nanoparticles’ 3D shape by aspect maps: Determination of the morphology of bacterial magnetic nanoparticles. Faraday Discuss 2016; 191:177-188. [DOI: 10.1039/c6fd00059b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Magnetic nanoparticles (MNPs) are widely investigated due to their potential use in various applications, ranging from electronics to biomedical devices. The magnetic properties of MNPs are strongly dependent on their size and shape (i.e., morphology), thus appropriate tools to investigate their morphology are fundamental to understand the physics of these systems. Recently a new approach to study nanoparticle morphology by Transmission Electron Microscopy (TEM) analysis has been proposed, introducing the so-called Aspect Maps (AMs). In this paper, a further evolution of the AM method is presented, allowing determination of the nanoparticles’ 3D shape by TEM image. As a case study, this paper will focus on magnetite nanoparticles (Fe3O4), with a mean size of ∼45 nm extracted from Magnetospirillum gryphiswaldense magnetostatic bacteria (MTB). The proposed approach gives a complete description of the nanoparticles’ morphology, allowing estimation of an average geometrical size and shape. In addition, preliminary investigation of the magnetic properties of MTB nanoparticles was performed, giving some insight into interparticle interactions and on the reversal mechanism of the magnetization.
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Alexandrakis V, Wallisch W, Hamann S, Varvaro G, Fidler J, Ludwig A. Combinatorial Development of Fe-Co-Nb Thin Film Magnetic Nanocomposites. ACS Comb Sci 2015; 17:698-703. [PMID: 26401900 DOI: 10.1021/acscombsci.5b00116] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A Fe-Co-Nb thin film materials library was deposited by combinatorial magnetron sputtering and investigated by high-throughput methods to identify new noncubic ferromagnetic phases, indicating that combinatorial experimentation is an efficient method to discover new ferromagnetic phases adequate for permanent magnet applications. Structural analysis indicated the formation of a new magnetic ternary compound (Fe,Co)3Nb with a hexagonal crystal structure (C36) embedded in an FeCo-based matrix. This nanocomposite exhibits characteristics of a two-phase ferromagnetic system, the so-called hard-soft nanocomposites, indicating that the new phase (Fe,Co)3Nb is ferromagnetic. Magnetic hysteresis loops at various angles revealed that the magnetization reversal process is governed by a domain wall pinning mechanism.
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Affiliation(s)
- Vasileios Alexandrakis
- Ruhr-University Bochum, Faculty of Mechanical Engineering,
Institute for Materials, 44801 Bochum, Germany
| | - Wolfgang Wallisch
- Institute
of Solid State Physics, Vienna University of Technology, Wiedner
Hauptstrasse 8-10, 1040 Vienna, Austria
| | - Sven Hamann
- Ruhr-University Bochum, Faculty of Mechanical Engineering,
Institute for Materials, 44801 Bochum, Germany
| | - Gaspare Varvaro
- ISM−CNR Area della Ricerca Roma1, Via Salaria km 29.300, C.P. 10, 00016 Monterotondo Scalo (RM), Italy
| | - Josef Fidler
- Institute
of Solid State Physics, Vienna University of Technology, Wiedner
Hauptstrasse 8-10, 1040 Vienna, Austria
| | - Alfred Ludwig
- Ruhr-University Bochum, Faculty of Mechanical Engineering,
Institute for Materials, 44801 Bochum, Germany
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Varvaro G, Peddis D, Barucca G, Mengucci P, Rodionova V, Chichay K, Testa AM, Agostinelli E, Laureti S. Highly Textured FeCo Thin Films Deposited by Low Temperature Pulsed Laser Deposition. ACS Appl Mater Interfaces 2015; 7:22341-22347. [PMID: 26378368 DOI: 10.1021/acsami.5b06030] [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] [Indexed: 06/05/2023]
Abstract
The effect of the deposition temperature (Tdep) on the crystallographic orientation of pulsed laser-deposited FeCo/MgO(100) thin film was determined by means of X-ray reflectivity and high resolution trasmission electron microscopy analysis and was correlated with the magnetic anisotropy properties measured by angle dependent hysteresis loops. Highly textured films with a bcc structure and very smooth surface were obtained even at room temperature, the film being [100] and [110] oriented, at Tdep=25 °C and 150 °C, respectively. The cubic symmetry is reflected in the angular dependence of remanent magnetization, showing a 4-fold character, whose in-plane distribution is consistent with the different crystallographic orientations of the films. The high structural quality, even at room temperature, is reflected in a high value of the saturation magnetization and low coercivity, matching the requirements for technological applications.
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Affiliation(s)
- Gaspare Varvaro
- Istituto di Struttura della Materia, CNR , Monterotondo Stazione, Roma 00015, Italy
| | - Davide Peddis
- Istituto di Struttura della Materia, CNR , Monterotondo Stazione, Roma 00015, Italy
| | - Gianni Barucca
- Università Politecnica delle Marche , Dipartimento SIMAU, Via Brecce Bianche, Ancona 60131, Italy
| | - Paolo Mengucci
- Università Politecnica delle Marche , Dipartimento SIMAU, Via Brecce Bianche, Ancona 60131, Italy
| | - Valeria Rodionova
- Innovation Park and Institute of Physics and Technology, Immanuel Kant Baltic Federal University , Kaliningrad 238300, Russian Federation
- National University of Science and Technology "MISiS" , Moscow 119049, Russia
| | - Ksenia Chichay
- Innovation Park and Institute of Physics and Technology, Immanuel Kant Baltic Federal University , Kaliningrad 238300, Russian Federation
| | - Alberto Maria Testa
- Istituto di Struttura della Materia, CNR , Monterotondo Stazione, Roma 00015, Italy
| | | | - Sara Laureti
- Istituto di Struttura della Materia, CNR , Monterotondo Stazione, Roma 00015, Italy
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23
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Rau JV, Cacciotti I, Laureti S, Fosca M, Varvaro G, Latini A. Bioactive, nanostructured Si-substituted hydroxyapatite coatings on titanium prepared by pulsed laser deposition. J Biomed Mater Res B Appl Biomater 2014; 103:1621-31. [PMID: 25557461 DOI: 10.1002/jbm.b.33344] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [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: 05/14/2014] [Revised: 10/27/2014] [Accepted: 12/02/2014] [Indexed: 11/11/2022]
Abstract
AIMS The aim of this work was to deposit silicon-substituted hydroxyapatite (Si-HAp) coatings on titanium for biomedical applications, since it is known that Si-HAp is able to promote osteoblastic cells activity, resulting in the enhanced bone ingrowth. MATERIALS AND METHODS Pulsed laser deposition (PLD) method was used for coatings preparation. For depositions, Si-HAp targets (1.4 wt % of Si), made up from nanopowders synthesized by wet method, were used. RESULTS Microstructural and mechanical properties of the produced coatings, as a function of substrate temperature, were investigated by scanning electron and atomic force microscopies, X-ray diffraction, Fourier transform infrared spectroscopy, and Vickers microhardness. In the temperature range of 400-600°C, 1.4-1.5 µm thick Si-HAp films, presenting composition similar to that of the used target, were deposited. The prepared coatings were dense, crystalline, and nanostructured, characterized by nanotopography of surface and enhanced hardness. Whereas the substrate temperature of 750°C was too high and led to the HAp decomposition. Moreover, the bioactivity of coatings was evaluated by in vitro tests in an osteoblastic/osteoclastic culture medium (α-Modified Eagle's Medium). CONCLUSIONS The prepared bioactive Si-HAp coatings could be considered for applications in orthopedics and dentistry to improve the osteointegration of bone implants.
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Affiliation(s)
- Julietta V Rau
- Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133, Rome, Italy
| | - Ilaria Cacciotti
- Università di Roma "Niccolò Cusano", Via Don Carlo Gnocchi, 3-00166, Rome, Italy.,Dipartimento di Ingegneria dell'Impresa, Università di Roma "Tor Vergata", UdR INSTM-"Roma Tor Vergata", Via del Politecnico, 1-00133, Rome, Italy
| | - Sara Laureti
- Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, 00016, Monterotondo Scalo (RM), Italy
| | - Marco Fosca
- Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133, Rome, Italy
| | - Gaspare Varvaro
- Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, 00016, Monterotondo Scalo (RM), Italy
| | - Alessandro Latini
- Dipartimento di Chimica, Università di Roma "La Sapienza", Piazzale Aldo Moro, 5-00185, Rome, Italy
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Laureti S, Brombacher C, Makarov D, Albrecht M, Peddis D, Varvaro G, D'Acapito F. EXAFS investigation of the role of Cu on the chemical order and lattice distortion in L10Fe–Pt–Cu thin films. J Appl Crystallogr 2014. [DOI: 10.1107/s1600576714019268] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
This work presents an extended X-ray absorption fine structure (EXAFS) characterization of ternary Fe–Pt–Cu alloys with different Cu content. The EXAFS measurements have been carried out at the CuKα and PtLIIIedges in order to describe the local environment around these elements in the Fe–Pt–Cu samples and to compare the structural evolution as a function of the Cu content. The EXAFS study, based on a substitutional model where the Cu atoms occupy Fe or Pt sites in the tetragonal structure, has been performed by using linear dichroism to enhance the sensitivity to differently oriented bonds and to gain a detailed description of the atomic environment. The study allowed the effects on the chemical order and lattice distortion induced by the Cu atoms to be distinguished experimentally. The determined positions of the Cu atoms in the chemically L10-ordered face-centred tetragonal lattice were correlated with the magnetic properties of Fe–Pt–Cu ternary alloys. In particular, the main effect of Cu atoms in the alloy is a linear reduction of thec/aratio, while the nonmonotonic behaviour of the chemical order is consistent with the variation of the magnetocrystalline anisotropy.
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Ball DK, Lenz K, Fritzsche M, Varvaro G, Günther S, Krone P, Makarov D, Mücklich A, Facsko S, Fassbender J, Albrecht M. Magnetic properties of granular CoCrPt:SiO 2 thin films deposited on GaSb nanocones. Nanotechnology 2014; 25:085703. [PMID: 24492459 DOI: 10.1088/0957-4484/25/8/085703] [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] [Indexed: 06/03/2023]
Abstract
We report on the effect of microstructure and geometrically induced modifications of the magnetic properties of granular CoCrPt:SiO2 films with weakly interacting magnetic grains deposited on pre-structured GaSb nanocone templates fabricated by an ion erosion technique. By tuning the irradiation conditions, nanocone patterns of different cone sizes were prepared (from 28 to 120 nm in diameter and 32 to 330 nm high, respectively). The influence of the intergranular exchange coupling was also investigated by varying the SiO2 content from 8 to 12 at.%. Deposition of CoCrPt:SiO2 on samples with small nanocones leads to a close magnetic grain packing, which results in the formation of extended magnetic domains larger than the average distance between the GaSb cones. In contrast, on larger nanocones, the magnetic coating grows on the side-walls, with a large separation between neighboring cones, leading to magnetic single-domain regions, which are correlated to the underlying structure. Magnetometry indicates that both remanence and coercivity decrease with increasing cone size and/or SiO2 content due to a combined effect of the angular distribution of the magnetic easy axis of the grains and the intergranular exchange coupling strength.
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Affiliation(s)
- D K Ball
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf e.V., Bautzner Landstraße 400, D-01328 Dresden, Germany. Technische Universität Dresden, D-01062 Dresden, Germany
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Laureti S, Varvaro G, Testa AM, Fiorani D, Agostinelli E, Piccaluga G, Musinu A, Ardu A, Peddis D. Magnetic interactions in silica coated nanoporous assemblies of CoFe2O4 nanoparticles with cubic magnetic anisotropy. Nanotechnology 2010; 21:315701. [PMID: 20622300 DOI: 10.1088/0957-4484/21/31/315701] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Magnetic interactions in silica coated spherical nanoporous assemblies of CoFe(2)O(4) nanoparticles have been investigated by low temperature field dependent remanent magnetization (M(DCD) and M(IRM)) and magnetization relaxation measurements. The synthesis procedure leads to the formation of spherical aggregates of about 50-60 nm in diameter composed of hexagonal shaped nanocrystals with shared edges. The negative deviation from the non-interacting case in the Henkel plot indicates the predominance of dipole-dipole interactions favouring the demagnetized state, although the presence of exchange interactions in the porous system cannot be excluded. The activation volume, derived from time dependent magnetization measurements, turns out to be comparable with the particle physical volume, thus indicating, in agreement with static and dynamic irreversible magnetization measurements, that the magnetization reversal actually involves individual crystals.
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Affiliation(s)
- S Laureti
- ISM-CNR, Area della Ricerca Roma1, Monterotondo Scalo (RM), Italy
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Agostinelli E, Laureti S, Varvaro G, Generosi A, Paci B, Rossi-Albertini V, Scavia G, Testa A. Study of structural microstructural and magnetic properties of very thin Co50Pt50 films deposited by PLD. Materials Science and Engineering: C 2007. [DOI: 10.1016/j.msec.2006.07.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Scavia G, Agostinelli E, Laureti S, Varvaro G, Paci B, Generosi A, Albertini VR, Kaciulis S, Mezzi A. Evolution of the Pt Layer Deposited on MgO(001) by Pulsed Laser Deposition as a Function of the Deposition Parameters: A Scanning Tunneling Microscopy and Energy Dispersive X-ray Diffractometry/Reflectometry Study. J Phys Chem B 2006; 110:5529-36. [PMID: 16539492 DOI: 10.1021/jp0554644] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A combined ultrahigh vacuum scanning tunneling microscopy (STM-UHV) and energy dispersive X-ray diffractometry/reflectometry (EDXD/EDXR) study of the evolution of face-centered cubic (fcc) Pt layer growth on MgO(100) by pulsed laser deposition as a function of the process parameters such as deposition temperature and deposition duration has been carried out. The aim of this study is to define the best experimental conditions to obtain a controlled film deposition selective on the Pt growth direction (either [111] or [002]). The evolution of the Pt surface morphology as a function of the deposition temperature (T(dep)) from 300 to 700 degrees C has been studied with STM and ED techniques. Results show that the Pt surface, characterized at T(dep) = 300 degrees C by a 3D island morphology, evolves at higher temperatures to a morphology in which the original islands coexist with a distribution of orthogonal 2D stripes. The two features can be associated with the [111] and [002] Pt growth directions of the fcc phase, respectively. For T(dep) = 700 degrees C, the island morphology of the (111) face completely disappears, while the merging process of the (002) stripes reaches completion. The evolution of the morphology at T(dep) = 600 degrees C as a function of the deposition time and thickness has then been studied with STM-UHV, revealing an initial growth of mosaic-like 3D islands. These independent islands, already interconnected, expand along two orthogonal directions and, for longer deposition times, lead to the texture of orthogonal stripes. The EDXR characterization providing the morphological parameters of the films, i.e., thickness and roughness, confirms the above observation and quantifies the effect of such morphological changes on the surface roughness of the Pt film, an important parameter for applications of Pt films as underlayer in magnetic recording media.
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Affiliation(s)
- Guido Scavia
- Area di Ricerca ROMA 1, Istituto di Struttura della Materia, CNR, via Salaria km 29.500, 00016 Monterotondo Scalo, Roma, Italy.
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