scholarly journals Magnetization reversal and anomalous dependence of the coercive field with temperature in MnAs epilayers grown on GaAs

2006 ◽  
Vol 74 (14) ◽  
Author(s):  
L. B. Steren ◽  
J. Milano ◽  
V. Garcia ◽  
M. Marangolo ◽  
M. Eddrief ◽  
...  
Keyword(s):  
Magnetization Reversal ◽  
Coercive Field ◽  
Anomalous Dependence

Tuning the coercive field by controlling the magnetization reversal process in permalloy modulated nanowires

2020 ◽  
Vol 512 ◽  
pp. 167045
Author(s):  
Guidobeth Sáez ◽  
Eduardo Cisternas ◽  
Pablo Díaz ◽  
Eugenio E. Vogel ◽  
Juan Pablo Burr ◽  
...  
Keyword(s):  
Magnetization Reversal ◽  
Coercive Field ◽  
Reversal Process ◽  
Magnetization Reversal Process

scholarly journals Nanocompositional Electron Microscopic Analysis and Role of Grain Boundary Phase of Isotropically Oriented Nd-Fe-B Magnets

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Gregor A. Zickler ◽  
Josef Fidler
Keyword(s):  
Domain Wall ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Magnetization Reversal ◽  
Coercive Field ◽  
Microscopic Analysis ◽  
Realistic Model ◽  
Boundary Phase ◽  
Electron Microscopic ◽  
The Impact

Nanoanalytical TEM characterization in combination with finite element micromagnetic modelling clarifies the impact of the grain misalignment and grain boundary nanocomposition on the coercive field and gives guidelines how to improve coercivity in Nd-Fe-B based magnets. The nanoprobe electron energy loss spectroscopy measurements obtained an asymmetric composition profile of the Fe-content across the grain boundary phase in isotropically oriented melt-spun magnets and showed an enrichment of iron up to 60 at% in the Nd-containing grain boundaries close to Nd2Fe14B grain surfaces parallel to the c-axis and a reduced iron content up to 35% close to grain surfaces perpendicular to the c-axis. The numerical micromagnetic simulations on isotropically oriented magnets using realistic model structures from the TEM results reveal a complex magnetization reversal starting at the grain boundary phase and show that the coercive field increases compared to directly coupled grains with no grain boundary phase independently of the grain boundary thickness. This behaviour is contrary to the one in aligned anisotropic magnets, where the coercive field decreases compared to directly coupled grains with an increasing grain boundary thickness, if Js value is > 0.2 T, and the magnetization reversal and expansion of reversed magnetic domains primarily start as Bloch domain wall at grain boundaries at the prismatic planes parallel to the c-axis and secondly as Néel domain wall at the basal planes perpendicular to the c-axis. In summary our study shows an increase of coercive field in isotropically oriented Nd-Fe-B magnets for GB layer thickness > 5 nm and an average Js value of the GB layer < 0.8 T compared to the magnet with perfectly aligned grains.

High Coercive Field and Magnetization Reversal in Core–Shell Cum Nanotwin Driven Ni/NiO Nanospheres

2011 ◽  
Vol 11 (3) ◽  
pp. 2632-2635
Author(s):  
Gunadhor S. Okram ◽  
Ajay Soni ◽  
D. T. Adroja ◽  
N. P. Lalla ◽  
T. Shripathi
Keyword(s):  
Magnetization Reversal ◽  
Coercive Field ◽  
Core Shell ◽  
High Coercive Field

Determination of eddy current losses and hysteresis losses in magnetic circuits of electrical machines

2020 ◽  
pp. 54-58
Author(s):  
S. M. Plotnikov
Keyword(s):  
Eddy Current ◽  
Magnetization Reversal ◽  
Eddy Currents ◽  
Technical Problem ◽  
Electrical Machines ◽  
Eddy Current Losses ◽  
Hysteresis Losses ◽  
Magnetic Circuits ◽  
Core Losses ◽  
Reversal Frequency

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.

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

1994 ◽  
Vol 18 (2) ◽  
pp. 193-196 ◽  
Author(s):  
H. Nishio ◽  
H. Taguchi ◽  
F. Hirata ◽  
T. Takeishi
Keyword(s):  
Magnetization Reversal ◽  
Fine Particles ◽  
Magnetic Aftereffect

COMPUTER SIMULATIONS OF MAGNETIZATION REVERSAL DYNAMICS

1993 ◽  
Vol 17 (S_1_MORIS_92) ◽  
pp. S1_255-257 ◽  
Author(s):  
Roscoe C. Giles ◽  
Masud Mansuripur
Keyword(s):  
Computer Simulations ◽  
Magnetization Reversal

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

2003 ◽  
Vol 777 ◽  
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.

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

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 [Dy<sub>2</sub>L<sub>2</sub>(<i>µ</i>-Cl)<sub>2</sub>(THF)<sub>2</sub>] has been made using a diamine-bis(phenolate) ligand, H<sub>2</sub>L. Magnetic studies show an energy barrier for magnetization reversal (<i>U</i><sub>eff</sub>) around 1000 K. Exchange-biasing effect is clearly seen in magnetic hysteresis with steps up to 4 K. <i>Ab</i> initio calculations exclude the possibility of pure dipolar origin of this effect leading to the conclusion that super-exchange <i>via</i> the chloride bridging ligands is important.

The Influence of the Soaking Process on Magnetization Saturation and Coercivity Field of the Classic Amorphous Alloy Fe61Co10Y8Nb1B20.

2018 ◽  
Vol 69 (10) ◽  
pp. 2819-2822
Author(s):  
Marcin Nabialek
Keyword(s):  
Magnetic Field ◽  
Saturation Magnetization ◽  
Coercive Field ◽  
Thermal Treatments ◽  
Solid Samples ◽  
Magnetization Saturation ◽  
Transmission Geometry ◽  
Negative Effect ◽  
Coercivity Field ◽  
The Magnetic Field

This study presents the results of Mossbauer research and magnetic properties. The tests were carried out for amorphous Fe61Co10Y8Nb1B20 alloys produced in the form of strips with a thickness of approximately 35 mm. Mossbauer spectra were measured in transmission geometry for solid samples. Measurements were taken for samples in solidified state and after two heating processes. The first process was carried out at 700K and 60 minutes, the second at 720K and 210 minutes. For the samples prepared in this way, magnetization tests were performed as a function of the magnetic field strength. The values of saturation magnetization and the value of the coercive field were determined from these matrices. It was found that the performed thermal treatments had a negative effect on the value of saturation magnetization and change in the value of the coercive field.

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