scholarly journals Effect of large mechanical stress on the magnetic properties of embedded Fe nanoparticles

2011 ◽  
Vol 2 ◽  
pp. 268-275 ◽  
Author(s):  
Srinivasa Saranu ◽  
Sören Selve ◽  
Ute Kaiser ◽  
Luyang Han ◽  
Ulf Wiedwald ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Data Storage ◽  
Dominant Role ◽  
Magnetic Film ◽  
Biaxial Stress ◽  
Magnetic Data ◽  
Particle Volume ◽  
Crystalline Anisotropy ◽  
Magneto Crystalline Anisotropy

Magnetic nanoparticles are promising candidates for next generation high density magnetic data storage devices. Data storage requires precise control of the magnetic properties of materials, in which the magnetic anisotropy plays a dominant role. Since the total magneto-crystalline anisotropy energy scales with the particle volume, the storage density in media composed of individual nanoparticles is limited by the onset of superparamagnetism. One solution to overcome this limitation is the use of materials with extremely large magneto-crystalline anisotropy. In this article, we follow an alternative approach by using magneto-elastic interactions to tailor the total effective magnetic anisotropy of the nanoparticles. By applying large biaxial stress to nanoparticles embedded in a non-magnetic film, it is demonstrated that a significant modification of the magnetic properties can be achieved. The stress is applied to the nanoparticles through expansion of the substrate during hydrogen loading. Experimental evidence for stress induced magnetic effects is presented based on temperature-dependent magnetization curves of superparamagnetic Fe particles. The results show the potential of the approach for adjusting the magnetic properties of nanoparticles, which is essential for application in future data storage media.

scholarly journals The effect of magneto-crystalline anisotropy on the properties of hard and soft magnetic ferrite nanoparticles

2019 ◽  
Vol 10 ◽  
pp. 1348-1359 ◽  
Author(s):  
Hajar Jalili ◽  
Bagher Aslibeiki ◽  
Ali Ghotbi Varzaneh ◽  
Volodymyr A Chernenko
Keyword(s):  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Magnetic Behavior ◽  
Soft Magnetic ◽  
Interparticle Interactions ◽  
Co Doping ◽  
Heat Efficiency ◽  
Crystalline Anisotropy ◽  
Structure Morphology ◽  
Magneto Crystalline Anisotropy

Recent advances in the field of magnetic materials emphasize that the development of new and useful magnetic nanoparticles (NPs) requires an accurate and fundamental understanding of their collective magnetic behavior. Studies show that the magnetic properties are strongly affected by the magnetic anisotropy of NPs and by interparticle interactions that are the result of the collective magnetic behavior of NPs. Here we study these effects in more detail. For this purpose, we prepared Co x Fe3− x O4 NPs, with x = 0–1 in steps of 0.2, from soft magnetic (Fe3O4) to hard magnetic (CoFe2O4) ferrite, with a significant variation of the magnetic anisotropy. The phase purity and the formation of crystalline NPs with a spinel structure were confirmed through Rietveld refinement. The effect of Co doping on structure, morphology and magnetic properties of Co x Fe3− x O4 samples was investigated. In particular, we examined the interparticle interactions in the samples by δm graphs and Henkel plots that have not been reported before in literature. Finally, we studied the hyperthermia properties and observed that the heat efficiency of soft Fe3O4 is about 4 times larger than that of hard CoFe2O4 ferrite, which was attributed to the high coercive field of samples compared with the external field amplitude.

Magnetische Eigenschaften der Normaltemperaturform von CsTmO2 / Magnetic Properties of the Normal-Temperature Form of CsTmO2

1979 ◽  
Vol 34 (8) ◽  
pp. 997-1002 ◽  
Author(s):  
Werner Urland
Keyword(s):  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Crystal Field ◽  
Ground State ◽  
Low Temperatures ◽  
Magnetic Behaviour ◽  
Magnetic Data ◽  
Angular Overlap Model ◽  
Temperature Form ◽  
Overlap Model

AbstractThe magnetic behaviour of the normal-temperature-form of CsTmO2 (NT-CsTmO2) has been studied in the temperature range between 2.9 and 251.3 K. In order to interpret the magnetic data a method applying the angular overlap model has been established to assess the crystal-field (CF) parameters of NT-CsTmO2 (CF symmetry: D3d) from the known CF parameters for Tm3+ substituted in YVO4 (CF symmetry: D2d)-With these CF parameters the observed magnetic properties of NT-CsTmO2 can be satisfactorily simulated. The calculation of the paramagnetic principal susceptibilities yields a high magnetic anisotropy, especially at low temperatures. The energy values of the CF levels of the 3H6 ground state are calculated.

Effects of the Co-Presence of Conflicting Magnetic Anisotropy in Ba Ferrite Particles

2010 ◽  
Vol 67 ◽  
pp. 108-112
Author(s):  
Giancarlo Bottoni
Keyword(s):  
Thermal Stability ◽  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Low Temperatures ◽  
Magnetocrystalline Anisotropy ◽  
Shape Anisotropy ◽  
Recording Media ◽  
Magnetization Switching ◽  
Crystalline Anisotropy ◽  
Thermal Stability Of

In Ba ferrite particles magnetocrystalline and shape anisotropies are contemporarily present and conflicting. The strength and evolution of the two anisotropies are studied, through the dependence of the anisotropy constants on temperature. While in pure Ba ferrite particles the anisotropy is uniaxial at all temperatures, since the magnetocrystalline anisotropy clearly prevails on shape anisotropy, in particles modified for employment in recording media the two anisotropies are comparable and at low temperatures the shape anisotropy result stronger than the crystalline anisotropy. Besides the irregular shape of the particles introduces further preferred directions for the magnetization. The Co/Ti-doped particles show a multiple axes anisotropy. The macroscopic magnetic properties are found in relationship with the evolution of the anisotropy. Also the influence that the presence of such multiple anisotropy has on the magnetization switching and on the thermal stability of the magnetization of the Ba ferrite particles is analyzed.

Interface effects on the magnetic properties of layered Ni2MnGa/Ni2MnSn alloys: A first-principles investigation

2016 ◽  
Vol 09 (06) ◽  
pp. 1642010 ◽  
Author(s):  
Biswanath Dutta ◽  
Ingo Opahle ◽  
Tilmann Hickel
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
Multilayer Systems ◽  
Crystalline Anisotropy ◽  
Additive Contribution ◽  
Spin Moments ◽  
Magneto Crystalline Anisotropy ◽  
Interface Effects

The effect of interfaces on the magnetic properties of multilayers is analyzed for Ni2MnGa/Ni2MnSn system using density functional theory. The Ni spin moments at the interface change by about 30% compared to the bulk value, whereas the effect on the Mn spin moments is much less pronounced. A similar strong effect is also observed for the Ni orbital moments at the interface. The magneto-crystalline anisotropy of the multilayer systems can be understood by the additive contribution of the respective values of strained bulk materials.

Perpendicular Magnetic Anisotropy and Atomic Ordering in FePd, Fe50Pd50-xPtx Alloy Films

2014 ◽  
Vol 215 ◽  
pp. 242-245
Author(s):  
Evgeny M. Artemyev ◽  
Lev E. Yakimov
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Phase Composition ◽  
Magnetic Anisotropy ◽  
Perpendicular Magnetic Anisotropy ◽  
Magnetic Data ◽  
Atomic Order ◽  
Data Recording ◽  
Alloy Films ◽  
Ordered Alloys

Phase composition, crystal structure and magnetic properties of ordering FePd and Fe50Pd50-xPtx(х = 1-10 atomic %) alloy films were studied. Spectral dependencies of Faraday rotation and optical absorption were measured. We studied how thermal treatment affects crystal structure, magnetization and coercive force in ordered alloys and how the degree of atomic order affects the value of perpendicular magnetic anisotropy. It was shown that near equiatomic ordered FePd and Fe50Pd50-xPtx(х = 1-10 at. %) alloy films can be used as medium for magnetic and thermo-magnetic data recording.

scholarly journals Magnetic Anisotropy of Dispersed Powders

1960 ◽  
Vol 13 (2) ◽  
pp. 196 ◽  
Author(s):  
FD Stacey
Keyword(s):  
Magnetic Anisotropy ◽  
Single Crystal ◽  
Ferromagnetic Material ◽  
Anisotropy Constant ◽  
Surprising Result ◽  
Inert Matrix ◽  
Crystalline Anisotropy ◽  
Iron Nickel ◽  
Small Grains ◽  
Magneto Crystalline Anisotropy

It is well known that in most rocks the ferromagnetic fraction occurs as small grains dispersed in a solid, magnetically inert matrix. Recently the magnetic anisotropy of rocks and of chondritic meteorites has been subjected to detailed study by the torque-meter method, and, in an attempt to obtain a physical understanding of the shape and crystal alignments of grains which cause magnetic anisotropy in these natural bodies, a number of artificial specimens have been prepared. Iron, nickel, and magnetite powders were mixed into solidifying media and allowed to set in a cylindrical mould in a 10 kilo-oersted field. The torque curves of the resulting specimens reveal a surprising result. It appears that single crystal magnetic grains tend to string together along lines of forc~, thus producing strongly anisotropic specimens, only when the first magneto crystalline anisotropy constant of the ferromagnetic material is positive.

scholarly journals Rare earth ion contribution in barium hexaferrite structure to a change of magnetocrystalline anisotropy to improving its magnetic properties

2020 ◽  
pp. 1-13
Author(s):  
I Gusti Agung Putra Adnyana
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Barium Hexaferrite ◽  
Particle Morphology ◽  
Solid State Reactions ◽  
Phase Identification ◽  
Rare Earth Ion ◽  
Crystalline Anisotropy ◽  
Materials Used ◽  
Magneto Crystalline Anisotropy

Rare earth ion contribution in barium hexaferrite structure to a change of magneto-crystalline anisotropy to improving its magnetic properties has been investigated. A series of simples of Ba1-xCexFe12O19 with the variation of x (x = 0.0-0.5) were prepared by solid-state reactions using mechanical deformation techniques. The oxide materials used for sample preparation are BaCO3, Fe2O3, and CeO2 with the ratio of material used is adjusted to the stoichiometric calculation for variations of Ce4+ substitution. The phase identification results show that the reaction took place perfectly and successfully formed a single-phase Ba1-xCexFe12O19 namely at the composition x = 0 and x = 0.1. while for the composition x> 0.1, it is formed in three phases. Particle morphology in the composition x = 0 and x = 0.1 has very good and uniform particle homogeneity across the surface of the sample in the form of polygonal particles. So the substitution of Ce atoms into the barium hexaferrite structure is only able at the composition limit x = 0.1. In the composition x = 0.1 has been able to increase the coercivity and magnetization fields. It can be concluded that the permanent magnet with the composition Ba0,9Ce0.1F12O19 gives the best results.

scholarly journals Structural, Dielectric and Magnetic properties of Yttrium doped Hematite Nanoparticle

2021 ◽  
Author(s):  
Vijay Kumar ◽  
Dharamvir Singh Ahlawat ◽  
Amrik Singh ◽  
Arun Kumar ◽  
Ompal Singh
Keyword(s):  
Health Care ◽  
Grain Size ◽  
Magnetic Properties ◽  
Rare Earth ◽  
Crystallite Size ◽  
Data Storage ◽  
Rare Earth Metals ◽  
Magnetic Data ◽  
Xrd Patterns ◽  
Rhombohedral Symmetry

Abstract Applicability of magnetic crystalline nanoparticles particularly in the diagnostic field of health care and magnetic data storage makes them highly important for various technological researches. Novel properties of prepared nanoparticles can be tuned with doping of rare earth metals. In the present research, Yttrium (Y) doped hematite nanocrystalline samples have been prepared at various compositions, Fe2 − 2xY2xO3 (x = 0.00, 0.02, 0.05, 0.08, 0.10) and magnetic properties are seen sensitive with dopants concentration. The variation in grain size from FE-SEM is found well collaborated with the crystallite size and strain determined by XRD measurements. Rietveld refinement of XRD patterns reveals the formation of rhombohedral symmetry with Rˉ3c space group of the samples. The dielectric and magnetic properties show wiggling behaviour with the concentration of doping metal. A shift towards weakly ferromagnetic conduct like behaviour has been confirmed with the doping of Y in hematite crystalline particles.

Micromagnetic Simulation on the Microwave Magnetic Properties of Glass-Coated Amorphous Alloy Microwires

2013 ◽  
Vol 668 ◽  
pp. 733-736
Author(s):  
Yong Jiang Di ◽  
Peng Jun Cao ◽  
Bi Jia ◽  
Jian Jun Jiang
Keyword(s):  
Finite Element Method ◽  
Magnetic Anisotropy ◽  
Magnetic Domain ◽  
Anisotropy Field ◽  
Magnetic Alloy ◽  
Microwave Resonance ◽  
Crystalline Anisotropy ◽  
Magnetic Spectrum ◽  
Simulation Results ◽  
Magneto Crystalline Anisotropy

The magnetic structure of the glass-coated magnetic alloy microwires were modeled based on the main magnetic domain structure and meshed by finite element method. The magnetic spectrum of the magnetic alloy microwires was calculated based on the micromagnetic theory. The simulation results of the magnetic spectrum of glass-coated magnetic alloy microwires showed that the magnetic anisotropy field increase as the magneto-crystalline anisotropy constants increase. The microwave resonance frequency increased accompanied by the reduction of the permeability and the increase of the magnetic anisotropy field of the glass-coated magnetic alloy microwires.

scholarly journals Investigation of Magnetic Anisotropy and Barkhausen Noise Asymmetry Resulting from Uniaxial Plastic Deformation of Steel S235

2021 ◽  
Vol 11 (8) ◽  
pp. 3600
Author(s):  
Martin Pitoňák ◽  
Miroslav Neslušan ◽  
Peter Minárik ◽  
Jiří Čapek ◽  
Katarína Zgútová ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Magnetic Anisotropy ◽  
Magnetic Coupling ◽  
Critical Threshold ◽  
Barkhausen Noise ◽  
Crystalline Anisotropy ◽  
The Asymmetry ◽  
Matrix Orientation ◽  
Magneto Crystalline Anisotropy ◽  
Insight Into

This study investigates alterations in magnetic anisotropy and the marked asymmetry in Barkhausen noise (MBN) signals after the uniaxial plastic straining of steel S235 obtained from a shipyard and used as standard structural steel in shipbuilding. It was found that the initial easy axis of magnetisation in the direction of previous rolling, and also in the direction of loading, becomes the hard axis of magnetisation as soon as the plastic strain attains the critical threshold. This behaviour is due to the preferential matrix orientation and the corresponding realignment of the magneto-crystalline anisotropy. Apart from the angular dependence of MBN, the asymmetry in the consecutive MBN bursts at the lower plastic strains is also analysed and explained as a result of magnetic coupling between the grains plastically strained and those unaffected by the tensile test. It was found that, by increasing the degree of plastic strain, the marked asymmetry in MBN tends to vanish. Moreover, the asymmetry in MBN bursts occurs in the direction of uniaxial tension and disappears in the perpendicular direction. Besides the MBN technique, XRD and EBSD techniques were also employed in order to provide a deeper insight into the investigated aspects.

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