On the Minimum of Magnetization Reversal Time

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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