Micromagnetic Simulation of Asymmetrical CoFe Nanorings

Domain wall motions and magnetization reversal processes in the nanoscale asymmetrical Co50Fe50rings have been studied using micromagnetic simulations. The results reveal that the switching fields and the plateau width of vortex state can be tuned through changing the asymmetrical parameter of magnetic nanorings. The chirality of vortex states can be easily controlled by the orientation of the applied magnetic field.

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Magnetization reversal in crossed double elliptic permalloy nanodisks studied by micromagnetic simulation

International Journal of Modern Physics B ◽

10.1142/s0217979218501564 ◽

2018 ◽

Vol 32 (13) ◽

pp. 1850156

Author(s):

Amaresh Chandra Mishra ◽

R. Giri

Keyword(s):

Magnetic Field ◽

External Magnetic Field ◽

Applied Magnetic Field ◽

Magnetization Reversal ◽

Major Axis ◽

Vortex State ◽

Micromagnetic Simulation ◽

Minor Axis ◽

Semi Major Axis ◽

Saturation State

The remanent state of elliptical permalloy nanodisks depends on the orientation of the applied magnetic field with respect to the major and minor axes of the nanodisks [A. C. Mishra, Int. J. Mod. Phys. B 30, 1650192 (2016)]. The remanent state is usually an onion state if the external magnetic field is along the major axis, and is a vortex state if the external magnetic field is along the minor axis. In this work, we have analyzed the magnetization reversal of a crossed elliptic disk of permalloy using micromagnetic simulation. This is a new shape where two identical elliptic disks with semi-major axis of length a and semi-minor axis of length b intersect such that they are perpendicular to each other. If the value of b is very close to that of a, then the remanent state is a near saturation state. As the ratio a/b goes down, new complex remanent states are observed. The hysteresis loss is found to be decreased gradually with the increment of b for a given value of b.

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Magnetization Reversal in NiFe Nano-triangles

MRS Proceedings ◽

10.1557/proc-1258-q11-18 ◽

2010 ◽

Vol 1258 ◽

Author(s):

Xinghua Wang ◽

Sarjoosing Goolaup ◽

Chunxiao Cong ◽

wensiang Lew

Keyword(s):

Thin Film ◽

Domain Wall ◽

Magnetization Reversal ◽

Micromagnetic Simulation ◽

Lateral Size ◽

Magnetic Reversal ◽

Micromagnetic Simulations ◽

Reversal Mechanism

AbstractWe have fabricated sub-100 nm triangles NiFe triangle arrays using NSL and the MOKE measurement and micromagnetic simulations were carried out to investigate the reversal mechanism of the arrays. Enhancement of coercivity compared to the thin film was observed in all the three arrays but in different degree from the MOKE measurement. With the increase of the lateral size of the triangle, the effect of the coercivity enhancing decreases. Micromagnetic simulation shows that instead of domain wall nucleation and annihilation in the thin film, the reversal mechanism of the 45 and 80 nm triangles is dominated by the coherent rotation. While in the 100 nm triangle, the magnetic reversal takes place via forming and reversing a V like sate.

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Magnetic skyrmions in FePt nanoparticles having Reuleaux 3D geometry: a micromagnetic simulation study

Nanoscale ◽

10.1039/c9nr04829d ◽

2019 ◽

Vol 11 (42) ◽

pp. 20102-20114 ◽

Cited By ~ 1

Author(s):

Vasileios D. Stavrou ◽

Drosos Kourounis ◽

Konstantinos Dimakopoulos ◽

Ioannis Panagiotopoulos ◽

Leonidas N. Gergidis

Keyword(s):

Finite Element ◽

Simulation Study ◽

Magnetization Reversal ◽

Magnetocrystalline Anisotropy ◽

Micromagnetic Simulation ◽

Fept Nanoparticles ◽

External Fields ◽

Micromagnetic Simulations ◽

3D Geometry ◽

Magnetic Skyrmions

The magnetization reversal in magnetic FePt nanoelements having Reuleaux 3D geometry is studied using Finite Element micromagnetic simulations. Multiple skyrmions are formed for a range of external fields and magnetocrystalline anisotropy values.

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Controllable two- vs three-state magnetization switching in single-layer epitaxial Pd1-xFex films and epitaxial Pd0.92Fe0.08/Ag/Pd0.96Fe0.04 heterostructure

10.3762/bxiv.2021.93.v1 ◽

2021 ◽

Author(s):

Igor Yanilkin ◽

Amir Gumarov ◽

Gulnaz Gizzatullina ◽

Roman Yusupov ◽

Lenar Tagirov

Keyword(s):

Magnetic Field ◽

Low Temperature ◽

Applied Magnetic Field ◽

Magnetization Reversal ◽

Easy Axis ◽

Magnetic State ◽

Magnetic Moments ◽

Single Layer ◽

Wide Range ◽

Ferromagnetic Layers

We have investigated the low-temperature magnetoresistive properties of a thin epitaxial Pd0.92Fe0.08 film at different directions of the current and the applied magnetic field. The obtained experimental results are well described within an assumption of a single-domain magnetic state of the film. In a wide range of the appled field directions, the magnetization reversal proceeds in two steps via the intermediate easy axis. An epitaxial heterostructure of two magnetically separated ferromagnetic layers, Pd0.92Fe0.08/Ag/Pd0.96Fe0.04, was synthesized and studied with the dc magnetometry. Its magnetic configuration diagram has been constructed and the conditions have been determined for a controllable switching between stable parallel, orthogonal, and antiparallel arrangements of magnetic moments of the layers.

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Study of Domain Wall Propagation in FePt and FePd Nanowires Driven by Sub-nanosecond Pulse of Magnetic Field by Micromagnetic Simulation

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/553/1/012017 ◽

2019 ◽

Vol 553 ◽

pp. 012017

Author(s):

Sulaiman Hawibowo ◽

Candra Kurniawan ◽

Dede Djuhana

Keyword(s):

Magnetic Field ◽

Domain Wall ◽

Micromagnetic Simulation ◽

Nanosecond Pulse ◽

Domain Wall Propagation

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Magnetic excitations in assemblies of dipolar coupled nanoparticles

EPJ Web of Conferences ◽

10.1051/epjconf/202024401015 ◽

2020 ◽

Vol 244 ◽

pp. 01015

Author(s):

Fabrice Boust ◽

Nicolas Vukadinovic

Keyword(s):

Vortex Core ◽

Dipolar Coupling ◽

High Surface ◽

Three Dimensional ◽

Low Frequency ◽

Vortex State ◽

Model Systems ◽

Spectral Position ◽

Micromagnetic Simulations ◽

Vortex States

The equilibrium magnetization configurations and the associated microwave susceptibility spectra of dipolar coupled nanoplatelets are explored using three-dimensional (3D) micromagnetic simulations. First, the case of periodic arrangements of nanoplatelets on square arrays is considered. As a result, a macro-vortex state defined as a flux closure pattern spreading over the whole array with or without a vortex core can be stabilized starting from an initial orthoradial magnetization configuration. For macro-vortex states with a vortex core, the linear excitation spectrum exhibits a sub-GHz resonance line ascribed to the vortex core dynamics at the array center. The features of this line (spectral position and amplitude) depend on the array size and the strength of the dipolar coupling through the interplatelet spacing. This resonance is also observed for macro-vortex states without a vortex core but only in the regime of a strong dipolar coupling. The effect of disorder is then investigated by numerically generating assemblies of nanoplatelets with a position disorder and, shape and size distributions. The micromagnetic simulations reveal flux closure magnetization configurations as well but without a vortex core. A low-frequency resonance appears in the susceptibility spectra for quite high surface contents of nanoplatelets but its amplitude is weaker compared to the case of periodic arrays. This line arises from a collective mode extended over a few nanoplatelets. A large variety of static and dynamical behaviors is thus evidenced resulting in a great complexity even in such model systems.

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Heating Efficiency of Triple Vortex State Cylindrical Magnetic Nanoparticles

Nanoscale Research Letters ◽

10.1186/s11671-019-3169-6 ◽

2019 ◽

Vol 14 (1) ◽

Cited By ~ 1

Author(s):

De Wei Wong ◽

Wei Liang Gan ◽

Yuan Kai Teo ◽

Wen Siang Lew

Keyword(s):

Magnetic Field ◽

Magnetic Nanoparticles ◽

Magnetic Fields ◽

Vortex State ◽

Magnetic Hyperthermia ◽

Relaxation Mechanism ◽

Micromagnetic Simulations ◽

Heating Efficiency ◽

Aspect Ratios ◽

Low Field

AbstractA well-established method for treating cancerous tumors is magnetic hyperthermia, which uses localized heat generated by the relaxation mechanism of magnetic nanoparticles (MNPs) in a high-frequency alternating magnetic field. In this work, we investigate the heating efficiency of cylindrical NiFe MNPs, fabricated by template-assisted pulsed electrodeposition combined with differential chemical etching. The cylindrical geometry of the MNP enables the formation of the triple vortex state, which increases the heat generation efficiency by four times. Using time-dependent calorimetric measurements, the specific absorption rate (SAR) of the MNPs was determined and compared with the numerical calculations from micromagnetic simulations and vibrating sample magnetometer measurements. The magnetization reversal of high aspect ratios MNPs showed higher remanent magnetization and low-field susceptibility leading to higher hysteresis losses, which was reflected in higher experimental and theoretical SAR values. The SAR dependence on magnetic field strength exhibited small SAR values at low magnetic fields and saturates at high magnetic fields, which is correlated to the coercive field of the MNPs and a characteristic feature of ferromagnetic MNPs. The optimization of cylindrical NiFe MNPs will play a pivotal role in producing high heating performance and biocompatible magnetic hyperthermia agents.

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