Determination of domain wall energy and critical single-domain particle size based on domain structure observations of ThMn12-type magnetic particles

2020 ◽  
Vol 513 ◽  
pp. 167244
Author(s):  
K. Kobayashi ◽  
K. Urushibata ◽  
T. Kuno ◽  
S. Suzuki ◽  
N. Sakuma ◽  
...  
Keyword(s):  
Particle Size ◽  
Domain Wall ◽  
Domain Structure ◽  
Magnetic Particles ◽  
Single Domain ◽  
Single Domain Particle ◽  
Domain Wall Energy

scholarly journals Effect of Mechanical Milling on the Magnetic Properties of SrFe12O19

2015 ◽  
Vol 12 (1) ◽  
pp. 28-30
Author(s):  
I Bsoul
Keyword(s):  
Particle Size ◽  
Magnetic Properties ◽  
Crystallite Size ◽  
Mechanical Milling ◽  
Single Phase ◽  
Strontium Ferrite ◽  
Single Domain ◽  
Single Domain Particle ◽  
Ferrite Sample

In this work, a single phase strontium ferrite sample was mechanically milled for 60 h. It has been found that the crystallite size reduced by 85%. A dramatic drop (from 4500 to 1600 Oe) in the coercive filed was also observed. The observed reduction in the coercivity was attributed to the reduction of the single domain particle size.

Squareness of NdFeB Stoner-Wohlfarth Hysteresis

2014 ◽  
Vol 802 ◽  
pp. 601-606
Author(s):  
Marcos Flavio de Campos ◽  
Fernanda A.S. da Silva ◽  
José Adilson de Castro
Keyword(s):  
Particle Size ◽  
General Result ◽  
Anisotropy Constant ◽  
Single Domain ◽  
Single Domain Particle ◽  
Hysteresis Curves ◽  
Intrinsic Coercivity ◽  
Grain Diameter

Hysteresis curves were calculated according the Stoner-Wohlfarth (SW) model using values of K2/K1from zero up to 0.25 (where K2is the 2ndorder anisotropy constant and where K1is the 1storder anisotropy constant). The SW calculations assume Nd2Fe14B nanocrystalline magnets with single domain particle size (grain diameter less than 150 nm). The effect of K2on several index of merit of magnets as BHmaxand squareness are discussed. As a general result, increasing K2, the intrinsic coercivity increases. However, the increase of K2almost does not improve the BHmaxof isotropic magnets. It is found that the effect of the K2/K1ratio is coupled with the effect of texture, i.e., the effect of K2is more significant for pronounced texture.

Application of Micromagnetic Models for Barium Ferrite Magnets

2015 ◽  
Vol 820 ◽  
pp. 199-204 ◽  
Author(s):  
Marcos Flavio de Campos ◽  
Fernanda A. Sampaio da Silva
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Coercive Force ◽  
Total Energy ◽  
Barium Ferrite ◽  
Magnetocrystalline Anisotropy ◽  
Single Domain ◽  
Square Root ◽  
Single Domain Particle ◽  
Magnetostatic Energy

The applicability of micromagnetics for phases with high magnetocrystalline anisotropy as barium ferrite Ba2Fe12O19and Nd2Fe14B is discussed. The Stoner-Wohlfarth model is very suitable for such phases, and also for PtFe and PtCo. It was discussed how to take into account the total energy of the system for grain size above the single domain particle size. For this situation of large grain size, the net magnetostatic energy of the system cannot be neglected. From energy considerations, it follows that the coercive force should decrease with the inverse of the square root of the grain size.

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