scholarly journals Dynamic symmetry loss of high-frequency hysteresis loops in single-domain particles with uniaxial anisotropy

2012 ◽  
Vol 324 (4) ◽  
pp. 466-470 ◽  
Author(s):  
Gabriel T. Landi
Keyword(s):  
High Frequency ◽  
Uniaxial Anisotropy ◽  
Hysteresis Loops ◽  
Single Domain ◽  
Dynamic Symmetry

scholarly journals High Frequency Hysteresis Losses on γ-Fe2O3 and Fe3O4: Susceptibility as a Magnetic Stamp for Chain Formation

Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 970 ◽  
Author(s):  
Irene Morales ◽  
Rocio Costo ◽  
Nicolas Mille ◽  
Gustavo da Silva ◽  
Julian Carrey ◽  
...  
Keyword(s):  
High Frequency ◽  
Specific Absorption Rate ◽  
Hysteresis Loops ◽  
Anisotropy Field ◽  
Spatial Arrangement ◽  
Hysteresis Losses ◽  
Heating Efficiency ◽  
Field Independent ◽  
Large Particles ◽  
Chain Ordering

In order to understand the properties involved in the heating performance of magnetic nanoparticles during hyperthermia treatments, a systematic study of different γ-Fe2O3 and Fe3O4 nanoparticles has been done. High-frequency hysteresis loops at 50 kHz carried out on particles with sizes ranging from 6 to 350 nm show susceptibility χ increases from 9 to 40 for large particles and it is almost field independent for the smaller ones. This suggests that the applied field induces chain ordering in large particles but not in the smaller ones due to the competition between thermal and dipolar energy. The specific absorption rate (SAR) calculated from hysteresis losses at 60 mT and 50 kHz ranges from 30 to 360 W/gFe, depending on particle size, and the highest values correspond to particles ordered in chains. This enhanced heating efficiency is not a consequence of the intrinsic properties like saturation magnetization or anisotropy field but to the spatial arrangement of the particles.

scholarly journals Integrated Magnetic Analyses for the Discrimination of Urban and Industrial Dusts

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1056
Author(s):  
Beata Górka-Kostrubiec ◽  
Tadeusz Magiera ◽  
Katarzyna Dudzisz ◽  
Sylwia Dytłow ◽  
Małgorzata Wawer ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Particles ◽  
Steel Production ◽  
Hysteresis Loops ◽  
Street Dust ◽  
Single Domain ◽  
Magnetic Fraction ◽  
Magnetic Methods ◽  
Urban Dusts ◽  
Traffic Related Pollution

Industrial and urban dusts were characterized by investigating their magnetic properties. Topsoil composed of technogenic magnetic particles (TMP) originating from areas affected by three ironworks, street dust mainly composed of traffic-related pollution, and particulate matter (PM) from urban agglomeration in Warsaw, Poland were investigated. Several magnetic methods, namely magnetic susceptibility, thermomagnetic curves, hysteresis loops, decomposition of isothermal remanent magnetization acquisition curves, and first-order reversal curves, were performed to evaluate the magnetic fraction of dust. Magnetite was the main magnetic phase in all types of samples, with a small amount of high-coercive hematite within ironworks and street dust samples. Significant differences were observed in the domain structure (grain size) of industrial and traffic-related magnetic particles. The grain size of TMP obtained from steel production was in the range of 5–20 µm and was predominated by a mixture of single-domain (SD) and multidomain (MD) grains, with the prevalence of SD grains in the topsoil affected by Třinec ironwork. The traffic-related dust contained finer grains with a size of about 0.1 µm, which is characteristic of the pseudo-single-domain (PSD)/SD threshold. Street dusts were composed of a slightly higher proportion of MD grains, while PM also revealed the typical behavior of superparamagnetic particles.

GMR, Structural, and Magnetic Studies in NiFeCo/Ag Multilayer thin Films

1994 ◽  
Vol 343 ◽  
Author(s):  
J.D. Jarratt ◽  
J.A. Barnard
Keyword(s):  
Giant Magnetoresistance ◽  
Uniaxial Anisotropy ◽  
Hysteresis Loops ◽  
Film Plane ◽  
Film Structure ◽  
X Ray Diffraction ◽  
Magnetic Studies ◽  
Lower Temperature ◽  
Deposited Films

ABSTRACTGiant Magnetoresistance (GMR), crystal structure, and magnetic properties have been investigated in a series of sputtered Ni66Fe16Co18/Ag multilayer films with induced uniaxial anisotropy. The film thickness ranges studied were 20 and 25 Å for NiFeCo, and 25 to 50 Å for Ag. GMR was only evident in the films after post-deposition annealing. This onset of GMR is thought to be due to the breaking up of the NiFeCo layers into ferromagnetic platelets or islands by the immiscible Ag diffusing perpendicular to the film plane along the grain boundaries. The magnitude and field sensitivity of the GMR was dependent on the annealing time and temperature. High angle x-ray diffraction (HXRD) was used to reveal the overall film structure and growth texture and low angle XRD (LXRD) was used to investigate the quality of the multilayer structures. M-H hysteresis loops revealed in-plane uniaxial anisotropy in as-deposited films which is eventually eliminated with annealing. The easy axis squareness experiences a pronounced decrease with lower temperature annealing, but then increases slightly with annealing temperature.

Construction of hysteresis loops of single domain elements and coupled permalloy ring arrays by magnetic force microscopy

2003 ◽  
Vol 93 (10) ◽  
pp. 8540-8542 ◽  
Author(s):  
Xiaobin Zhu ◽  
P. Grütter ◽  
V. Metlushko ◽  
Y. Hao ◽  
F. J. Castaño ◽  
...  
Keyword(s):  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Hysteresis Loops ◽  
Single Domain ◽  
Force Microscopy

scholarly journals Magnetic Properties of Manganese-Zinc Soft Ferrite Ceramic for High Frequency Applications

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3173
Author(s):  
Lucian-Gabriel Petrescu ◽  
Maria-Cătălina Petrescu ◽  
Valentin Ioniță ◽  
Emil Cazacu ◽  
Cătălin-Daniel Constantinescu
Keyword(s):  
Magnetic Properties ◽  
High Frequency ◽  
High Efficiency ◽  
Magnetic Circuit ◽  
Hysteresis Loops ◽  
Vibrating Sample Magnetometer ◽  
Soft Magnetic ◽  
Mnzn Ferrite ◽  
Manganese Zinc ◽  
Soft Ferrite

A soft magnetic MnZn-type ferrite is considered for high frequency applications. First, the morphological, structural, and chemical composition of the material are presented and discussed. Subsequently, by using a vibrating sample magnetometer (VSM), the hysteresis loops are recorded. The open magnetic circuit measurements are corrected by employing demagnetization factors, and by taking into consideration the local magnetic susceptibility. Finally, the hysteresis losses are estimated by the Steinmetz approach, and the results are compared with available commercial information provided by selected MnZn ferrite manufacturers. Such materials are representative in planar inductor and transformer cores due to their typically low losses at high frequency, i.e., up to several MHz, in low-to-medium power applications and providing high efficiency of up to 97%–99%.

Singularity in high-frequency susceptibility of thin magnetic films with uniaxial anisotropy

JETP Letters ◽  
2001 ◽  
Vol 74 (4) ◽  
pp. 226-230 ◽  
Author(s):  
B. A. Belyaev ◽  
A. V. Izotov ◽  
S. Ya. Kiparisov
Keyword(s):  
High Frequency ◽  
Uniaxial Anisotropy ◽  
Magnetic Films ◽  
Thin Magnetic Films

Spin Reorientation Transition and Magnetization Reversal Mechanism of Gd Doped FeCo High-Frequency Soft Magnetic Thin Films

2014 ◽  
Vol 924 ◽  
pp. 141-151 ◽  
Author(s):  
Yu Rong An ◽  
Yue Li ◽  
Zhen Wang ◽  
Ya Lu Zuo ◽  
Li Xi
Keyword(s):  
Thin Films ◽  
Magnetic Anisotropy ◽  
Magnetization Reversal ◽  
High Frequency ◽  
Uniaxial Anisotropy ◽  
Spin Reorientation ◽  
Spin Reorientation Transition ◽  
Sputtering Power ◽  
Deposition Power ◽  
Reversal Mechanism

The magnetic FeCoGd thin films with various sputtering power from 10 to 30 W were fabricated on glass substrates by magnetron co-sputtering. The crystal structure of as-deposited FeCoGd thin films was investigated by X-ray diffraction. And an increasing trend of grain size with the increasing sputtering power was shown. When sputtering power is below 30 W, the films exhibited obviously in-plane uniaxial magnetic anisotropy, and the in-plane magnetic anisotropy field Hkdecreased with increasing deposition power. Moreover, good high frequency characteristics were obtained. The magnetization reversal mechanism has been investigated via the in-plane angular dependences of the magnetization and the coercivity. The experimental data points indicated that the magnetization reversal mechanism of FeCoGd film with in-plane uniaxial anisotropy is domain-wall depinning and coherent rotation when the applied field is close to the easy axis and hard axis, respectively. A spin reorientation transition phenomenon was observed when deposition power is larger than 30 W. A stripe domain structure for the sample with 30 W deposition power was developed due to a dominated perpendicular magnetic anisotropy.

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