scholarly journals Narrow Segment Driven Multistep Magnetization Reversal Process in Sharp Diameter Modulated Fe67Co33 Nanowires

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3077
Author(s):  
Javier García ◽  
Jose A. Fernández-Roldán ◽  
Roque González ◽  
Miguel Méndez ◽  
Cristina Bran ◽  
...  
Keyword(s):  
Data Storage ◽  
Magnetization Reversal ◽  
Domain Walls ◽  
Nanowire Array ◽  
Magnetic Hysteresis ◽  
Magnetic Domain ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Magnetic Nanomaterials ◽  
Magnetic Nanowires

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.

scholarly journals Magnetization Reversal Process and Magnetostatic Interactions in Fe56Co44/SiO2/Fe3O4 Core/Shell Ferromagnetic Nanowires with Non-Magnetic Interlayer

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2282
Author(s):  
Javier García ◽  
Alejandro M. Manterola ◽  
Miguel Méndez ◽  
Jose Angel Fernández-Roldán ◽  
Víctor Vega ◽  
...  
Keyword(s):  
Data Storage ◽  
Magnetization Reversal ◽  
Domain Walls ◽  
Magnetic Domain ◽  
Hysteresis Loops ◽  
Magnetic Data ◽  
Core Shell ◽  
The Core ◽  
Shell Nanostructures ◽  
Magnetostatic Interactions

Nowadays, numerous works regarding nanowires or nanotubes are being published, studying different combinations of materials or geometries with single or multiple layers. However, works, where both nanotube and nanowires are forming complex structures, are scarcer due to the underlying difficulties that their fabrication and characterization entail. Among the specific applications for these nanostructures that can be used in sensing or high-density magnetic data storage devices, there are the fields of photonics or spintronics. To achieve further improvements in these research fields, a complete understanding of the magnetic properties exhibited by these nanostructures is needed, including their magnetization reversal processes and control of the magnetic domain walls. In order to gain a deeper insight into this topic, complex systems are being fabricated by altering their dimensions or composition. In this work, a successful process flow for the additive fabrication of core/shell nanowires arrays is developed. The core/shell nanostructures fabricated here consist of a magnetic nanowire nucleus (Fe56Co44), grown by electrodeposition and coated by a non-magnetic SiO2 layer coaxially surrounded by a magnetic Fe3O4 nanotubular coating both fabricated by means of the Atomic Layer Deposition (ALD) technique. Moreover, the magnetization reversal processes of these coaxial nanostructures and the magnetostatic interactions between the two magnetic components are investigated by means of standard magnetometry and First Order Reversal Curve methodology. From this study, a two-step magnetization reversal of the core/shell bimagnetic nanostructure is inferred, which is also corroborated by the hysteresis loops of individual core/shell nanostructures measured by Kerr effect-based magnetometer.

scholarly journals Two-Step Magnetization Reversal FORC Fingerprint of Coupled Bi-Segmented Ni/Co Magnetic Nanowire Arrays

Nanomaterials ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 548 ◽  
Author(s):  
Javier García Fernández ◽  
Víctor Vega Martínez ◽  
Andy Thomas ◽  
Víctor de la Prida Pidal ◽  
Kornelius Nielsch
Keyword(s):  
Magnetization Reversal ◽  
Nanowire Array ◽  
Magnetic Domain ◽  
Magnetic Behavior ◽  
Relative Difference ◽  
Nanowire Arrays ◽  
Magnetic Interactions ◽  
Magnetic Configuration ◽  
Reversal Process ◽  
Magnetization Reversal Process

First Order Reversal Curve (FORC) analysis has been established as an appropriate method to investigate the magnetic interactions among complex ferromagnetic nanostructures. In this work, the magnetization reversal mechanism of bi-segmented nanowires composed by long Co and Ni segments contacted at one side was investigated, as a model system to identify and understand the FORC fingerprint of a two-step magnetization reversal process. The resulting hysteresis loop of the bi-segmented nanowire array exhibits a completely different magnetic behavior than the one expected for the magnetization reversal process corresponding to each respective Co and Ni nanowire arrays, individually. Based on the FORC analysis, two possible magnetization reversal processes can be distinguished as a consequence of the ferromagnetic coupling at the interface between the Ni and Co segments. Depending on the relative difference between the magnetization switching fields of each segment, the softer magnetic phase induces the switching of the harder one through the injection and propagation of a magnetic domain wall when both switching fields are comparable. On the other hand, if the switching fields values differ enough, the antiparallel magnetic configuration of nanowires is also possible but energetically unfavorable, thus resulting in an unstable magnetic configuration. Making use of the different temperature dependence of the magnetic properties for each nanowire segment with different composition, one of the two types of magnetization reversal is favored, as demonstrated by FORC analyses.

Laser ablated pure non-crystalline Co thin films for inductors for ultra-high frequencies

2001 ◽  
Vol 674 ◽  
Author(s):  
V. Madurga ◽  
J. Vergara ◽  
C. Favieres
Keyword(s):  
Thin Films ◽  
Domain Walls ◽  
Spontaneous Magnetization ◽  
Magnetic Domain ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Soft Magnetic ◽  
High Frequencies ◽  
Magnetic Domain Walls ◽  
Deposited Films

ABSTRACTNon-crystalline Co thin films have been prepared by pulsed laser ablation deposition. From the M-H hysteresis loops measurements, a soft magnetic behavior is observed. Néel type magnetic domain walls are observed in the as-deposited films. The spontaneous magnetization, Ms(T = 300 K), is ≍ 860 emu/cm3. After annealing at 500 oC, Ms(T = 300 K) is ≍ 1460 emu/cm3. The extrapolated to zero K resistance decreases almost two orders of magnitude from the as deposited samples to the crystallized heated at 500 °C ones. A trilayer Co/Cu/Co has shown a real part magnetic susceptibility of 120 at 100 MHz. In the 100 MHz to 1 GHz frequency range, a perpendicular bias magnetic field increased this value up to 270, remaining almost constant for all range.

scholarly journals Single Diameter Modulation Effects on Ni Nanowire Array Magnetization Reversal

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3403
Author(s):  
Luis C. C. Arzuza ◽  
Victor Vega ◽  
Victor M. Prida ◽  
Karoline O. Moura ◽  
Kleber R. Pirota ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Domain Wall ◽  
Long Range ◽  
Magnetization Reversal ◽  
Nanowire Array ◽  
Magnetic Behavior ◽  
Nanowire Arrays ◽  
Magnetic Nanowires ◽  
Range Interaction ◽  
Domain Wall Propagation

Geometrically modulated magnetic nanowires are a simple yet efficient strategy to modify the magnetic domain wall propagation since a simple diameter modulation can achieve its pinning during the nanowire magnetization reversal. However, in dense systems of parallel nanowires, the stray fields arising at the diameter interface can interfere with the domain wall propagation in the neighboring nanowires. Therefore, the magnetic behavior of diameter-modulated nanowire arrays can be quite complex and depending on both short and long-range interaction fields, as well as the nanowire geometric dimensions. We applied the first-order reversal curve (FORC) method to bi-segmented Ni nanowire arrays varying the wide segment (45–65 nm diameter, 2.5–10.0 μm length). The FORC results indicate a magnetic behavior modification depending on its length/diameter aspect ratio. The distributions either exhibit a strong extension along the coercivity axis or a main distribution finishing by a fork feature, whereas the extension greatly reduces in amplitude. With the help of micromagnetic simulations, we propose that a low aspect ratio stabilizes pinned domain walls at the diameter modulation during the magnetization reversal. In this case, long-range axial interaction fields nucleate a domain wall at the nanowire extremities, while short-range ones could induce a nucleation at the diameter interface. However, regardless of the wide segment aspect ratio, the magnetization reversal is governed by the local radial stray fields of the modulation near null magnetization. Our findings demonstrate the capacity of distinguishing between complex magnetic behaviors involving convoluted interaction fields.

scholarly journals Micromagnetic Simulations of Fe and Ni Nanodot Arrays Surrounded by Magnetic or Non-Magnetic Matrices

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 349
Author(s):  
Devika Sudsom ◽  
Andrea Ehrmann
Keyword(s):  
Magnetic Materials ◽  
Data Storage ◽  
Magnetization Reversal ◽  
Hysteresis Loops ◽  
Object Oriented ◽  
Basic Research ◽  
Memory Systems ◽  
The Other ◽  
Micromagnetic Simulations ◽  
Nanodot Arrays

Combining clusters of magnetic materials with a matrix of other magnetic materials is very interesting for basic research because new, possibly technologically applicable magnetic properties or magnetization reversal processes may be found. Here we report on different arrays combining iron and nickel, for example, by surrounding circular nanodots of one material with a matrix of the other or by combining iron and nickel nanodots in air. Micromagnetic simulations were performed using the OOMMF (Object Oriented MicroMagnetic Framework). Our results show that magnetization reversal processes are strongly influenced by neighboring nanodots and the magnetic matrix by which the nanodots are surrounded, respectively, which becomes macroscopically visible by several steps along the slopes of the hysteresis loops. Such material combinations allow for preparing quaternary memory systems, and are thus highly relevant for applications in data storage and processing.

scholarly journals Influence of elastically pinned magnetic domain walls on magnetization reversal in multiferroic heterostructures

2015 ◽  
Vol 92 (5) ◽  
Author(s):  
Arianna Casiraghi ◽  
Teresa Rincón Domínguez ◽  
Stefan Rößler ◽  
Kévin J. A. Franke ◽  
Diego López González ◽  
...  
Keyword(s):  
Magnetization Reversal ◽  
Domain Walls ◽  
Magnetic Domain ◽  
Magnetic Domain Walls ◽  
Multiferroic Heterostructures

Microstructure and Magnetic Behavior of One-Dimensional Co0.5Zn0.5Fe2O4 Nanofibers

2011 ◽  
Vol 284-286 ◽  
pp. 861-865
Author(s):  
Jun Xiang ◽  
Guang Zhen Zhou ◽  
Yan Qiu Chu ◽  
Xiang Qian Shen
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Average Diameter ◽  
Diffraction Field ◽  
One Dimensional ◽  
Morphological Variations ◽  
Transmission Electron

One-dimensional Co0.5Zn0.5Fe2O4 nanostructures (nanofibers) with an average diameter of 154 nm were fabricated by electrospinning. These nanofibers were characterized by X–ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Magnetic hysteresis loops were measured for randomly oriented and aligned Co0.5Zn0.5Fe2O4 nanofibers, in comparison with the corresponding powder sample synthesized using the conventional sol-gel process. The differences in magnetic properties are observed between the Co0.5Zn0.5Fe2O4 nanofibers and powders, and these differences mainly arise from the grain size and morphological variations between these two materials. In determining the magnetization ease axis for the aligned Co0.5Zn0.5Fe2O4 nanofibers the shape anisotropy is slightly dominant competing with the magnetocrystalline anisotropy.

Behavior of Magnetic Domains in Single Magnetic Nanowire with Shallow Trench along Length Direction Observed by Magnetic Force Microscopy

2013 ◽  
Vol 1527 ◽  
Author(s):  
Mitsunobu Okuda ◽  
Yasuyoshi Miyamoto ◽  
Eiichi Miyashita ◽  
Naoto Hayashi
Keyword(s):  
Domain Walls ◽  
Hard Disk Drives ◽  
Magnetic Domain ◽  
Magnetic Memory ◽  
Magnetic Nanowires ◽  
Magnetic Domains ◽  
Electric Circuits ◽  
Recording Density ◽  
Magnetic Nanowire ◽  
Length Direction

ABSTRACTWe have proposed new magnetic memories using parallel-aligned nanowires without mechanical moving parts, in order to achieve the ultra high transfer rate of more than 144 Gbps for Super Hi-Vision TV. In the magnetic memory using nanowires, the data are stored as the magnetic domains with up or down magnetization in magnetic nanowires, and the domains are shifted quite faster by applying optimum current along the nanowire direction for data writing and reading purpose. Since the electric circuits and the insulation space between the neighbor nanowires are necessary for moving the magnetic domain walls, the areal recording density is essentially reduced as compared with that of conventional hard disk drives. In this study, in order to increase the areal recording density of magnetic nanowire memory, we have tried to act one magnetic nanowire as the virtual multiple data tracks. The shallow scratched trench was introduced using scanning probe microscopy along the length direction on the surface of a single nanowire to form multiple internal tracks, and we have succeeded in realizing a couple of virtual tracks states.

The Heating Effects of Dextran Coated Iron Oxides

2006 ◽  
Vol 962 ◽  
Author(s):  
Qi Zeng ◽  
Ian Baker ◽  
Jack Hoopes
Keyword(s):  
Particle Size ◽  
Specific Absorption Rate ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Particle Sizes ◽  
Heating Effects ◽  
Magnetic Hysteresis Loops ◽  
Heating Behavior ◽  
Potential Use

ABSTRACTThe structural and quasi-static magnetic behaviors and the temperature rises of three Dextran-coated maghemite nanoparticles subjected to alternating magnetic field (AMF) were investigated for potential use in magnetic hyperthermia treatments. In order to elucidate the effect of the hydrodynamic particle size on the specific absorption rate, the temperature rises for various hydrodynamic particle sizes were investigated in AMFs of various strengths and frequencies. Structural characterization was performed using a TEM and a SEM as well as by dynamic light scattering, and the quasi-static magnetic hysteresis loops were measured using a VSM. The heating behavior is discussed in relation to the magnetic behavior and particle size. While it was found that the heating mechanism for the ferromagnetic particles was mainly magnetic hysteresis losses, Brownian relaxation losses also contributed to the heating.

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