Single Diameter Modulation Effects on Ni Nanowire Array Magnetization Reversal

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.

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

Nanomaterials ◽

10.3390/nano8070548 ◽

2018 ◽

Vol 8 (7) ◽

pp. 548 ◽

Cited By ~ 8

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.

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

Nanomaterials ◽

10.3390/nano11113077 ◽

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.

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Subsystem domination influence on magnetization reversal in designed magnetic patterns in ferrimagnetic Tb/Co multilayers

Scientific Reports ◽

10.1038/s41598-020-80004-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Łukasz Frąckowiak ◽

Feliks Stobiecki ◽

Gabriel David Chaves-O’Flynn ◽

Maciej Urbaniak ◽

Marek Schmidt ◽

...

Keyword(s):

Domain Wall ◽

Magnetization Reversal ◽

Domain Walls ◽

Compensation Point ◽

Relative Sign ◽

Reversal Process ◽

Effective Magnetization ◽

Domain Wall Propagation ◽

Characteristic Features ◽

Magnetization Reversal Process

AbstractRecent results showed that the ferrimagnetic compensation point and other characteristic features of Tb/Co ferrimagnetic multilayers can be tailored by He+ ion bombardment. With appropriate choices of the He+ ion dose, we prepared two types of lattices composed of squares with either Tb or Co domination. The magnetization reversal of the first lattice is similar to that seen in ferromagnetic heterostructures consisting of areas with different switching fields. However, in the second lattice, the creation of domains without accompanying domain walls is possible. These domain patterns are particularly stable because they simultaneously lower the demagnetizing energy and the energy associated with the presence of domain walls (exchange and anisotropy). For both lattices, studies of magnetization reversal show that this process takes place by the propagation of the domain walls. If they are not present at the onset, the reversal starts from the nucleation of reversed domains and it is followed by domain wall propagation. The magnetization reversal process does not depend significantly on the relative sign of the effective magnetization in areas separated by domain walls.

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Magnetization reversal dynamics, nucleation, pinning, and domain wall propagation in perpendicularly magnetized ultrathin cobalt films: Influence of the Co deposition rate

Journal of Applied Physics ◽

10.1063/1.3506533 ◽

2010 ◽

Vol 108 (9) ◽

pp. 093924 ◽

Cited By ~ 14

Author(s):

R. Belhi ◽

A. Adanlété Adjanoh ◽

J. Vogel ◽

M. Ayadi ◽

K. Abdelmoula

Keyword(s):

Domain Wall ◽

Deposition Rate ◽

Magnetization Reversal ◽

Cobalt Films ◽

Domain Wall Propagation

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Fast Domain Wall Propagation under an Optimal Field Pulse in Magnetic Nanowires

Physical Review Letters ◽

10.1103/physrevlett.104.037206 ◽

2010 ◽

Vol 104 (3) ◽

Cited By ~ 27

Author(s):

Z. Z. Sun ◽

J. Schliemann

Keyword(s):

Domain Wall ◽

Magnetic Nanowires ◽

Field Pulse ◽

Domain Wall Propagation

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Magnetoresistance of Nanoscale Domain Walls Formed in Arrays of Parallel Nanowires

SPIN ◽

10.1142/s2010324719500048 ◽

2019 ◽

Vol 09 (01) ◽

pp. 1950004

Author(s):

Jingchun Wang ◽

Floriano Cuccureddu ◽

Rafael Ramos ◽

Cormac Ó. Coileáin ◽

Igor V. Shvets ◽

...

Keyword(s):

Thin Films ◽

Domain Wall ◽

Exchange Interaction ◽

Exchange Bias ◽

Room Temperature ◽

Domain Walls ◽

Nanowire Array ◽

Bias Field ◽

Nanowire Arrays ◽

Exchange Bias Field

We present the possibility of enhancing magnetoresistance (MR) by controlling nanoscale domain wall (DW) width in a planar nanowire array. Results based on micromagnetic calculations show that DW width decreases with increasing exchange bias field and decreases with reducing exchange interaction between neighboring nanowires. Fe/Fe3O4 nanowire arrays were grown on [Formula: see text]-plane sapphire to demonstrate the feasibility of this concept, and an enhanced MR ratio of 3.7% was observed at room temperature. compared with flat and stepped Fe3O4 thin films.

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Attenuation of Protein Adsorption on Static and Vibrating Magnetic Nanowires

MRS Proceedings ◽

10.1557/proc-877-s8.4 ◽

2005 ◽

Vol 877 ◽

Author(s):

Kristy M. Ainslie ◽

Gaurav Sharma ◽

Maureen A. Dyer ◽

Craig A. Grimes ◽

Michael V. Pishko

Keyword(s):

Cell Adhesion ◽

Host Response ◽

Nanowire Array ◽

The Body ◽

Nanowire Arrays ◽

Enzyme Linked Immunosorbent Assay ◽

Magnetic Nanowires ◽

Nanostructured Surfaces ◽

Protein Adhesion

AbstractThe research described here investigates the hypothesis that nanoarchitecture contained in a nanowire array is capable of attenuating the adverse host response, biofouling, generated when medical devices, such as sensors, are implanted in the body. This adverse host response generates an avascular fibrous mass transfer barrier between the device and the analyte of interest, disabling the sensor. Numerous studies have indicated that surface chemistry and architecture modulated the host response. These findings lead us to hypothesize that nanostructured surfaces will significantly inhibit the formation of an avascular fibrous capsule. We are investigating whether vibrating magnetostrictive nanowires, formed in nanowire arrays, can prevent protein and cell adhesion. Magnetostrictive nanowires are fabricated by electroplating a ferromagnetic metal alloy into the pores of a nanoporous alumina template. The ferromagnetic nanowires are made to vibrate by altering the magnetic field surrounding the wires. Enzyme-linked immunosorbent assay (ELISA) and other protein assays were used to study protein adhesion on the nanowire arrays. These results display a reduced protein adhesion per surface area of static nanowires. The vibrating nanowires show a further reduction in protein adhesion, compared to static wires. Studies were also preformed to investigate the effects of nanoarchitecture have on cell adhesion. These studies were performed with both static and vibrating nanowires. Preliminary protein adhesion studies have shown that a nanowire arrays modulate protein adhesion in vitro.

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