The Suppression of Demagnetizing Field Heterogeneity in Ferromagnetic Powders

2015 ◽  
Vol 233-234 ◽  
pp. 629-632 ◽  
Author(s):  
Roman Yaroslavtsev ◽  
Sergey Komogortsev ◽  
Lydia Chekanova ◽  
Ludmila Kuzovnikova ◽  
Elena Denisova ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Magnetic Phase ◽  
Hysteresis Loops ◽  
Magnetic Film ◽  
Cobalt Alloys ◽  
Demagnetizing Field ◽  
Field Heterogeneity ◽  
Demagnetizing Fields ◽  
Nonmagnetic Matrix ◽  
Good Agreement

The two ways of reducing the dispersion of the demagnetizing fields in magnetic powders of cobalt alloys have been tested: the isolation of magnetic particles in nonmagnetic matrix and compaction of the powders. The ferromagnetic resonance (FMR) and the hysteresis loops of the pretreated magnetic powders were investigated. The FMR linewidth is significantly narrowed both with increasing of the nonmagnetic fraction in the samples prepared by the first way and with increasing of relative density of the compacts. The limit case of FMR linewidth in continuous magnetic film there is no dispersion of the demagnetizing fields is in good agreement with discussed data. The hysteresis loops of powder with the particles coated by the non-magnetic phase became narrow and easy saturated with increasing of nonmagnetic phase fraction.

Overcoats and Lubrication for Thin Film Disks

MRS Bulletin ◽  
1990 ◽  
Vol 15 (3) ◽  
pp. 45-52 ◽  
Author(s):  
A.M. Homola ◽  
C.M. Mate ◽  
G.B. Street
Keyword(s):  
Thin Film ◽  
Data Storage ◽  
Magnetic Particles ◽  
Areal Density ◽  
Magnetic Film ◽  
Alloy Thin Film ◽  
Magnetic Media ◽  
Disk Interface ◽  
Storage Devices ◽  
Particulate Media

Metallic alloy thin film media and ever decreasing head-to-media spacing make severe demands on storage devices. Decreasing head-to-media separation is critical for high storage densities but it also leads to increased slider-disk interactions, which can cause slider and disk wear or even head crashes. Wear can also occur when drives start and stop when the slider contacts the disk at relatively high speeds. The reliability and durability of thin film disks, which provide much higher areal density than conventional oxide disks with particulate media, are achieved by the use of very thin overcoat materials and surface lubricants. This article summarizes the approaches taken in the industry to enhance the tribological performance of magnetic media, with special emphasis on the basic understanding of the processes occurring at the slider-disk interface.The continuous rise in the demand for storage capacity at a competitive price is the prime motivator of the changes we have seen in the data storage industry. It is clearly stimulating the present move away from particulate media, which has long dominated all fields of data storage, i.e., tape, rigid, and flexible disks, to the thin film storage media. Particulate storage devices use magnetic media formulated by dispersing magnetic particles, usually iron oxides, in an organic binder. In thin film storage devices, the storage medium is a continuous magnetic film, usually a cobalt alloy, made either by sputtering or by electroless plating.

Magnetic Phase Transition in MnSi Based on the First Principle Calculations of Electronic Structure and Spin Fluctuation Theory

2019 ◽  
Vol 289 ◽  
pp. 198-204
Author(s):  
Aleksandr Povzner ◽  
Tatyana A. Nogovitsyna ◽  
Arkadij G. Volkov ◽  
Tagir Nuretdinov
Keyword(s):  
Phase Transition ◽  
Electronic Structure ◽  
Magnetic Phase Transition ◽  
Magnetic Phase ◽  
Spin Fluctuation ◽  
Fluctuation Theory ◽  
Ministry Of Education ◽  
Spin Correlations ◽  
The Russian Federation ◽  
Good Agreement

Based on the spin-fluctuation theory and LSDA + U + SO-calculations of the electronic structure, the spin states arising in the region of the magnetic phase transition in the helicoidal ferromagnet MnSi are studied. Within the framework of the stated model of the electronic structure, a temperature dependence of the homogeneous magnetic susceptibility is obtained near the temperature of the magnetic phase transition, which is in good agreement with experiment. At the temperature of the transition to the paramagnetic state, the left chirality vanishes, and spin correlations arise with a radius equal to the length of the spin helix, which then decreases with temperature. The results were obtained within the framework of the assignment of the Ministry of Education and Science of the Russian Federation, contract 3.9521.2017 / 8.9

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.

Hysteresis Loops of Soft and Hard Magnetic Composited Wires

2013 ◽  
Vol 774-776 ◽  
pp. 763-766
Author(s):  
Yin Feng Li ◽  
Su Qin Feng ◽  
Lan Zhong Li ◽  
Pei Ying Chen ◽  
Peng Liu
Keyword(s):  
Magnetic Field ◽  
Magnetic Phase ◽  
Hysteresis Loops ◽  
Dipolar Interaction ◽  
Magnetic Alloys ◽  
Amorphous Wires ◽  
Two Phases ◽  
Measured Magnetic Field

Samples composed of soft and hard magnetic alloys were tailored by two steps annealing the same Fe-based amorphous wires. Then the measurements of hysteresisμ0Mloop have been performed upon the samples. The evolutions of loops with the fraction of hard magnetic phase and the measured magnetic field indicated the existence of dipolar interaction between the two phases.

Iron(II) 2-methylimidazolate and copper(II) 1,2,4-triazolate complexes: systems exhibiting long-range ferromagnetic ordering at low temperatures

1999 ◽  
Vol 77 (4) ◽  
pp. 425-433 ◽  
Author(s):  
Steven J Rettig ◽  
Alan Storr ◽  
David A Summers ◽  
Robert C Thompson ◽  
James Trotter
Keyword(s):  
Magnetic Phase ◽  
Hysteresis Loops ◽  
Indirect Evidence ◽  
Direct Methods ◽  
Weak Ferromagnetism ◽  
Spin Structures ◽  
Canted Spin ◽  
Ferromagnetic Ordering ◽  
Applied Fields ◽  
Tetrahedral Iron

Crystals of [Fe (2methylimidazolate)2·0.13(FeCp2)]x,1, are orthorhombic, a = 8.0654(11), b = 15.3504(5), c = 19.3388(9) Å, Z = 8, space group Pnnm. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R (F, I [Formula: see text] 3σ(I)) = 0.057 (Rw (F2, all data) = 0.142). The structure involves tetrahedral iron(II) centers linked in chains by single imidazolate ligand bridges. The chains are cross-linked by additional imidazolates to generate a complex 3-D network of linear channels in which ferrocene molecules are trapped. [Cu(1,2,4-triazolate)2]x, 2, is shown by indirect evidence to have a polymeric structure in which copper(II) ions are bridged by triazolate ligands. Magnetic susceptibilities were measured on powdered samples over the temperature range 2-300 K at applied fields of 0-55 000 G. Both materials exhibit antiferromagnetic exchange at temperatures above a magnetic phase transition: 27 K for 1 and 35 K for 2. At temperatures below these transitions the compounds exhibit weak ferromagnetism, likely resulting from canted spin structures. Cycling the applied magnetic field between +55 000 G and -55 000 G at 4.8 K generates hysteresis loops for both materials. Remnant magnetizations of 200 and 55 cm3 G mol-1 and coercive fields of 5000 and 2500 G are obtained for 1 and 2, respectively.Key words: iron, 2-methylimidazolate, copper, 1,2,4-triazolate, canted spins, ferromagnets.

scholarly journals Modeling of magnetic properties (Cr/NiO/Ni) based multi-layers deposited by magnetron sputtering using Preisach model

2017 ◽  
Author(s):  
A. Bendjerad ◽  
A. Benhaya ◽  
S. Boukhtache ◽  
M. Zergoug ◽  
K. Benyahia
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Magnetron Sputtering ◽  
Room Temperature ◽  
Hysteresis Loops ◽  
Preisach Model ◽  
Substrate Plane ◽  
Glass Substrates ◽  
Substrate Distance ◽  
Good Agreement

In the present work, thin films of Cr/NiO/Ni are deposited on glass substrates using RF magnetron sputteringtechnique. The uniformity and homogeneity of the prepared films were controlled by varying the power of the source, the target-substrate distance and the pressure of the plasma gas which is argon. In order to test the Preisach Model, we carried outmeasurements according to two directions: parallel and perpendicular to the substrate plane using a Vibrating SampleMagnetometer at room temperature. Good agreement has been obtained by comparing the experimental hysteresis loops to theones determined using Preisach model. We conclude that this model is powerful in predicting the magnetic properties ofmultilayer systems. # Cr/NiO/Ni #MAGNETRON_SPUTTERING #PREISACH MODEL #MAGNETIC_HYSTERESIS

Magnetization curves for ferromagnetic single crystals

1948 ◽  
Vol 193 (1032) ◽  
pp. 72-88 ◽  
Keyword(s):  
Single Crystals ◽  
Applied Field ◽  
Oblate Spheroid ◽  
Domain Theory ◽  
Magnetization Curves ◽  
Demagnetizing Field ◽  
Long Rod ◽  
Ferromagnetic Single Crystals ◽  
Internal Strains ◽  
Good Agreement

Magnetization curves for iron single crystals above the ‘knee’ are derived on the basis of domain theory for the case where the specimen is finite and the field is applied in an arbitrary direction with respect to the crystal axes. The shape of the specimen is important for the magnetization process and it is shown that in many cases the demagnetizing field must be such as to make the field actually acting in the crystal have a direction of symmetry (e. g. [111] or [110]) whatever the direction of the applied field. The cases of an oblate spheroid with its equatorial plane a (100) plane of the crystal and of a long rod with arbitrary orientation are considered in detail. In these cases simple expressions for the magnetization curves are obtained. There is good agreement with the experimental results of various authors for both parallel and normal components of magnetization. A method for correcting for the effect of internal strains is indicated.

Magnetic properties of a tri-decorated graphene structure: Monte Carlo study

2016 ◽  
Vol 30 (32) ◽  
pp. 1650233
Author(s):  
A. Jabar ◽  
N. Tahiri ◽  
L. Bahmad ◽  
A. Benyoussef
Keyword(s):  
Monte Carlo ◽  
Magnetic Properties ◽  
Phase Diagrams ◽  
Ground State ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Monte Carlo Study ◽  
Magnetic Hysteresis Loops ◽  
Reduced Temperature ◽  
Good Agreement

In this paper, we study the magnetic properties of a tri-decorated [Formula: see text] graphene structure using Monte Carlo simulations (MCS). Indeed, we first elaborate the ground state phase diagrams and then, we found that from [Formula: see text] phases, the only stable configurations are: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]. For low reduced temperature values, the partial magnetizations are found to be in good agreement with the corresponding ground state phase diagrams. The corresponding partial susceptibilities show a notable peak around the reduced temperature value 2.0 in the absence of the external magnetic field [Formula: see text] and crystal field [Formula: see text]. To complete this study, we present and discuss the magnetic hysteresis loops.

Magneto—Optical Properties of Amorphous TbFe Alloys

1985 ◽  
Vol 58 ◽  
Author(s):  
M. Mansuripur ◽  
M. Ruane ◽  
P. Wolniansky ◽  
S. Chase ◽  
R. Rosenvold
Keyword(s):  
Mean Field ◽  
Hysteresis Loops ◽  
Perpendicular Magnetic Anisotropy ◽  
Field Approximation ◽  
Anisotropy Energy ◽  
Optical Methods ◽  
Mean Field Approximation ◽  
Kerr Rotation ◽  
The Mean ◽  
Good Agreement

ABSTRACTHysteresis loops and anisotropy energy constants are measured in a magneto—optical system that combines Kerr rotation and ellipticity to enhance signal strength. Temperature dependence of the polar Kerr effect is compared with the magnetization of the iron subnetwork in the mean—field approximation and good agreement is obtained. Perpendicular magnetic anisotropy is studied by magneto—optical methods, yielding the first two coefficients of the series expansion of anisotropy energy in terms of the angleof deviation from the easy axis.

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