Magnetization reversal of FePt hard/soft stacked nanocomposite particle assembly

The division of the total core losses in the electrical steel of the magnetic circuit into two components – losses dueto hysteresis and eddy currents – is a serious technical problem, the solution of which will effectively design and construct electrical machines with magnetic circuits having low magnetic losses. In this regard, an important parameter is the exponent α, with which the frequency of magnetization reversal is included in the total losses in steel. Theoretically, this indicator can take values from 1 to 2. Most authors take α equal to 1.3, which corresponds to the special case when the eddy current losses are three times higher than the hysteresis losses. In fact, for modern electrical steels, the opposite is true. To refine the index α, an attempt was made to separate the total core losses on the basis that the hysteresis component is proportional to the first degree of the magnetization reversal frequency, and the eddy current component is proportional to the second degree. In the article, the calculation formulas of these components are obtained, containing the values of the total losses measured in idling experiments at two different frequencies, and the ratio of these frequencies. It is shown that the rational frequency ratio is within 1.2. Presented the graphs and expressions to determine the exponent α depending on the measured no-load losses and the frequency of magnetization reversal.

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Magnetic Aftereffect and Magnetization Reversal of Sr-Ferrite Fine Particles.

Journal of the Magnetics Society of Japan ◽

10.3379/jmsjmag.18.193 ◽

1994 ◽

Vol 18 (2) ◽

pp. 193-196 ◽

Cited By ~ 3

Author(s):

H. Nishio ◽

H. Taguchi ◽

F. Hirata ◽

T. Takeishi

Keyword(s):

Magnetization Reversal ◽

Fine Particles ◽

Magnetic Aftereffect

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COMPUTER SIMULATIONS OF MAGNETIZATION REVERSAL DYNAMICS

Journal of the Magnetics Society of Japan ◽

10.3379/jmsjmag.17.s1_255 ◽

1993 ◽

Vol 17 (S_1_MORIS_92) ◽

pp. S1_255-257 ◽

Cited By ~ 1

Author(s):

Roscoe C. Giles ◽

Masud Mansuripur

Keyword(s):

Computer Simulations ◽

Magnetization Reversal

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Magnetization dynamics of irradiation-fabricated perpendicularly magnetized dots inside a softer magnetic matrix

MRS Proceedings ◽

10.1557/proc-777-t6.4 ◽

2003 ◽

Vol 777 ◽

Cited By ~ 2

Author(s):

T. Devolder ◽

M. Belmeguenai ◽

C. Chappert ◽

H. Bernas ◽

Y. Suzuki

Keyword(s):

Domain Wall ◽

Magnetic Anisotropy ◽

Magnetization Reversal ◽

Ion Irradiation ◽

Magnetic Nanostructures ◽

Magnetic Storage ◽

Exchange Field ◽

Static Magnetization ◽

Specific Domain ◽

Helium Ion

AbstractGlobal Helium ion irradiation can tune the magnetic properties of thin films, notably their magneto-crystalline anisotropy. Helium ion irradiation through nanofabricated masks can been used to produce sub-micron planar magnetic nanostructures of various types. Among these, perpendicularly magnetized dots in a matrix of weaker magnetic anisotropy are of special interest because their quasi-static magnetization reversal is nucleation-free and proceeds by a very specific domain wall injection from the magnetically “soft” matrix, which acts as a domain wall reservoir for the “hard” dot. This guarantees a remarkably weak coercivity dispersion. This new type of irradiation-fabricated magnetic device can also be designed to achieve high magnetic switching speeds, typically below 100 ps at a moderate applied field cost. The speed is obtained through the use of a very high effective magnetic field, and high resulting precession frequencies. During magnetization reversal, the effective field incorporates a significant exchange field, storing energy in the form of a domain wall surrounding a high magnetic anisotropy nanostructure's region of interest. The exchange field accelerates the reversal and lowers the cost in reversal field. Promising applications to magnetic storage are anticipated.

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Exchange-Biasing in a Dinuclear Dysprosium(III) Single-Molecule Magnet with a Large Energy Barrier for Magnetization Reversal

10.26434/chemrxiv.10260494 ◽

2019 ◽

Author(s):

Tian Han ◽

Marcus J. Giansiracusa ◽

Zi-Han Li ◽

You-Song Ding ◽

Nicholas F. Chilton ◽

...

Keyword(s):

Single Molecule ◽

Magnetization Reversal ◽

Energy Barrier ◽

Magnetic Hysteresis ◽

Large Energy ◽

Magnetic Studies ◽

Bridging Ligands ◽

Single Molecule Magnet ◽

Exchange Biasing

A dichlorido-bridged dinuclear dysprosium(III) single-molecule magnet [Dy2L2(µ-Cl)2(THF)2] has been made using a diamine-bis(phenolate) ligand, H2L. Magnetic studies show an energy barrier for magnetization reversal (Ueff) around 1000 K. Exchange-biasing effect is clearly seen in magnetic hysteresis with steps up to 4 K. Ab initio calculations exclude the possibility of pure dipolar origin of this effect leading to the conclusion that super-exchange via the chloride bridging ligands is important.

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Magnetization Reversal of Ferromagnetic CoFeB Films and CoFeB/Ta/CoFeB Heterostructures in the Stray Field of Fe/Fe3O4 Nanoparticles

Journal of Experimental and Theoretical Physics ◽

10.1134/s1063776120090046 ◽

2020 ◽

Vol 131 (4) ◽

pp. 607-617

Author(s):

O. V. Koplak ◽

E. I. Kunitsyna ◽

R. S. Allayarov ◽

S. Mangin ◽

N. V. Granovskii ◽

...

Keyword(s):

Magnetization Reversal ◽

Fe3o4 Nanoparticles ◽

Stray Field

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Magnetization reversal in pac-man shaped Fe nanostructures with varying aperture

Journal of Magnetism and Magnetic Materials ◽

10.1016/j.jmmm.2021.168205 ◽

2021 ◽

pp. 168205

Author(s):

Fatima-Zohra Bachar ◽

Christian Schröder ◽

Andrea Ehrmann

Keyword(s):

Magnetization Reversal

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Magnetic properties of (Bi1−xLax)(Fe,Co)O3 films fabricated by a pulsed DC reactive sputtering and demonstration of magnetization reversal by electric field

Scientific Reports ◽

10.1038/s41598-021-90547-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Munusamy Kuppan ◽

Daichi Yamamoto ◽

Genta Egawa ◽

Sivaperuman Kalainathan ◽

Satoru Yoshimura

Keyword(s):

Electric Field ◽

Magnetization Reversal ◽

High Performance ◽

Magnetic Domain ◽

Magnetic Film ◽

Film Plane ◽

Force Microscopy ◽

Domain Structures ◽

Pulsed Dc ◽

Submicron Scale

Abstract(Bi1−xLax)(Fe,Co)O3 multiferroic magnetic film were fabricated using pulsed DC (direct current) sputtering technique and demonstrated magnetization reversal by applied electric field. The fabricated (Bi0.41La0.59)(Fe0.75Co0.25)O3 films exhibited hysteresis curves of both ferromagnetic and ferroelectric behavior. The saturated magnetization (Ms) of the multiferroic film was about 70 emu/cm3. The squareness (S) (= remanent magnetization (Mr)/Ms) and coercivity (Hc) of perpendicular to film plane are 0.64 and 4.2 kOe which are larger compared with films in parallel to film plane of 0.5 and 2.5 kOe. The electric and magnetic domain structures of the (Bi0.41La0.59)(Fe0.75Co0.25)O3 film analyzed by electric force microscopy (EFM) and magnetic force microscopy (MFM) were clearly induced with submicron scale by applying a local electric field. This magnetization reversal indicates the future realization of high performance magnetic device with low power consumption.

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

Nanomaterials ◽

10.3390/nano11020349 ◽

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.

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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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