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Influence of ferromagnetic layer thickness on the Gilbert damping and magnetocrystalline anisotropy in PLD grown epitaxial Co2FeSi Heusler alloy thin films. RESULTS IN SURFACES AND INTERFACES 2022. [DOI: 10.1016/j.rsurfi.2022.100052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Sharma P, Jain A, Chatterjee R. Enhanced magnetic performance in exchange-coupled CoFe 2O 4-LaFeO 3nanocomposites. NANOTECHNOLOGY 2021; 33:105708. [PMID: 34844232 DOI: 10.1088/1361-6528/ac3e31] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/29/2021] [Indexed: 06/13/2023]
Abstract
Nanocomposite oxide system of (x)CoFe2O4-(100-x)LaFeO3with different weight percent of core-shell structured CoFe2O4(x = 0, 20, 40, 50, 80, 100) and LaFeO3were fabricated, via a two-step sol-gel wet-chemical synthesis technique. The phase formation of the composites was confirmed by x-ray diffraction and the structural parameters of both the phases were attained from the Rietveld refinement results of XRD patterns. The elemental composition and microstructure of the resulting nanocomposites were examined by using energy-dispersive x-ray spectroscopy and high-resolution transmission electron microscopy technique, respectively. The detailed magnetometry studies at 300 K and 5 K reveal that the inter-and intra-phase magnetic interactions affect the saturation magnetization (MS), remanence magnetization (MR) and coercivity (HC) values of this bi-magnetic system. The remarkable feature of 'pinched magnetic hysteresis loop' was evidenced in the [(50) CoFe2O4- (50)LaFeO3] composite, leading to a lesser magnetic loss factor and better magnetic performance of this sample. The report depicts an improved interfacial exchange coupling at 5 K, for the nanocomposites of core-shell morphology and offers an understanding or explanation of improved magnetic performance for the (50)CoFe2O4- (50)LaFeO3nanocomposite and opens up an important way to design new multiferroic applications in low magnetic fields.
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Affiliation(s)
- Priyanka Sharma
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Anjali Jain
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Ratnamala Chatterjee
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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Del-Pozo-Bueno D, Varela M, Estrader M, López-Ortega A, Roca AG, Nogués J, Peiró F, Estradé S. Direct Evidence of a Graded Magnetic Interface in Bimagnetic Core/Shell Nanoparticles Using Electron Magnetic Circular Dichroism (EMCD). NANO LETTERS 2021; 21:6923-6930. [PMID: 34370953 DOI: 10.1021/acs.nanolett.1c02089] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Interfaces play a crucial role in composite magnetic materials and particularly in bimagnetic core/shell nanoparticles. However, resolving the microscopic magnetic structure of these nanoparticles is rather complex. Here, we investigate the local magnetization of antiferromagnetic/ferrimagnetic FeO/Fe3O4 core/shell nanocubes by electron magnetic circular dichroism (EMCD). The electron energy-loss spectroscopy (EELS) compositional analysis of the samples shows the presence of an oxidation gradient at the interface between the FeO core and the Fe3O4 shell. The EMCD measurements show that the nanoparticles are composed of four different zones with distinct magnetic moment in a concentric, onion-type, structure. These magnetic areas correlate spatially with the oxidation and composition gradient with the magnetic moment being largest at the surface and decreasing toward the core. The results show that the combination of EELS compositional mapping and EMCD can provide very valuable information on the inner magnetic structure and its correlation to the microstructure of magnetic nanoparticles.
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Affiliation(s)
- Daniel Del-Pozo-Bueno
- LENS-MIND, Department Enginyeries Electrònica i Biomèdica, Universitat de Barcelona, Martí i Franques 1, E-08028 Barcelona, Spain
- Institute of Nanoscience and Nanotechnology of the University of Barcelona (IN2UB), Avenida Diagonal 645, E-08028 Barcelona, Spain
| | - María Varela
- Departamento de Física de Materiales e Instituto Pluridisciplinar, Universidad Complutense de Madrid (UCM), 28040 Madrid, Spain
| | - Marta Estrader
- Institute of Nanoscience and Nanotechnology of the University of Barcelona (IN2UB), Avenida Diagonal 645, E-08028 Barcelona, Spain
- Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, Martí i Franques 1, E-08028 Barcelona, Spain
| | - Alberto López-Ortega
- Departamento de Ciencias, Universidad Pública de Navarra, 31006 Pamplona, Spain
- Institute for Advanced Materials and Mathematics INAMAT, Universidad Pública de Navarra, 31006 Pamplona, Spain
| | - Alejandro G Roca
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Josep Nogués
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- ICREA, Pg. Lluís Companys 23, E-08010 Barcelona, Spain
| | - Francesca Peiró
- LENS-MIND, Department Enginyeries Electrònica i Biomèdica, Universitat de Barcelona, Martí i Franques 1, E-08028 Barcelona, Spain
- Institute of Nanoscience and Nanotechnology of the University of Barcelona (IN2UB), Avenida Diagonal 645, E-08028 Barcelona, Spain
| | - Sònia Estradé
- LENS-MIND, Department Enginyeries Electrònica i Biomèdica, Universitat de Barcelona, Martí i Franques 1, E-08028 Barcelona, Spain
- Institute of Nanoscience and Nanotechnology of the University of Barcelona (IN2UB), Avenida Diagonal 645, E-08028 Barcelona, Spain
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Magnetism of Nanoparticles: Effect of the Organic Coating. NANOMATERIALS 2021; 11:nano11071787. [PMID: 34361173 PMCID: PMC8308320 DOI: 10.3390/nano11071787] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/30/2021] [Accepted: 07/01/2021] [Indexed: 12/23/2022]
Abstract
The design of novel multifunctional materials based on nanoparticles requires tuning of their magnetic properties, which are strongly dependent on the surface structure. The organic coating represents a unique tool to significantly modify the surface structure trough the bonds between the ligands of the organic molecule and the surface metal atoms. This work presents a critical overview of the effects of the organic coating on the magnetic properties of nanoparticles trough a selection of papers focused on different approaches to control the surface structure and the morphology of nanoparticles’ assemblies.
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