scholarly journals An ab initio study of the magnetic properties of strontium hexaferrite

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
C. Tejera-Centeno ◽  
S. Gallego ◽  
J. I. Cerdá
Keyword(s):  
Magnetic Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Strontium Hexaferrite ◽  
Multiscale Approach ◽  
Neel Temperature ◽  
Néel Temperature ◽  
Hubbard U ◽  
Exchange Constants ◽  
O 19

AbstractThe magnetic properties of $${\text{SrFe}}_{12}{\text{O}}_{19}$$ SrFe 12 O 19 , a paradigmatic hexaferrite for permanent magnet applications, have been addressed in detail combining density functional theory including spin–orbit coupling and a Hubbard U term with Monte Carlo simulations. This multiscale approach allows to estimate the Néel temperature of the material from ab initio exchange constants, and to determine the influence of different computational conditions on the magnetic properties by direct comparison versus available experimental data. It is found that the dominant influence arises from the choice of the Hubbard U term, with a value in the 2–3 eV range as the most adequate to quantitatively reproduce the two most relevant magnetic properties of this material, namely: its large perpendicular magnetocrystalline anisotropy and its elevated Néel temperature.

scholarly journals DFT-Mbj Study of Electronic and Magnetic Properties of Cubic Cecro3 Compound: An Ab-Initio Investigation

2017 ◽  
Vol 1 (1) ◽  
pp. 27-36
Author(s):  
M. Rashid ◽  
M. A. Iqbal ◽  
N. A. Noor
Keyword(s):  
Magnetic Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Exchange Constant ◽  
Local Spin Density Approximation ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Electronic And Magnetic Properties ◽  
Exchange Constants ◽  
First Time

By considering density functional theory (DFT) in terms of ab-initio investigation, we have explored the structural, electronic and magnetic properties of cubic CeCrO3 for the first time. In order to determine the structural stability of cubic CeCrO3 compound, we optimized the structure of CeCrO3 in non-magnetic (NM), ferromagnetic (FM) and Anti-ferromagnetic (AFM) phases by using PBE generalized gradient approximation (GGA) functional to find the exchangecorrelation potential. From structural optimization, the FM phase of CeCrO3 is observed to be stable. For computing electronic and magnetic properties, thelately advanced modified Becke and Johnson local (spin) density approximation (mBJLDA) is used. Calculated band structures and density of states plots with an integer magnetic moment of 4 μB and reveal half-metallic character. In addition, s–d exchange constants (N0α) and p–d exchange constant (N0β) are determined, which are in agreement with a distinctive magneto-optical experiment.

Synthesis process, magnetic and electronic properties of ferrite nanoparticle MnFe2O4

2018 ◽  
Vol 14 (4) ◽  
pp. 663-675
Author(s):  
R. Masrour ◽  
M. Ben Ali ◽  
H. El Moussaoui ◽  
Mohamed Hamedoun ◽  
A. Benyoussef ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Synthesis Process ◽  
Physical Parameters ◽  
Full Potential ◽  
Theory Approach ◽  
Content Type ◽  
Electronic And Magnetic Properties ◽  
Ferrite Nanoparticle

Purpose The purpose of this paper is to synthesize the manganese ferrite nanoparticle MnFe2O4 and to investigate the structure, size and to study the electronic and the magnetic properties of MnFe2O4 nanoparticles. Design/methodology/approach The co-precipitation method is used to synthesize the MnFe2O4. The structure and size were investigated by X-ray diffraction. The superconducting quantum interference device is used to determine the some magnetic ground. From theoretical investigation point of view self-consistent ab initio calculations, based on density functional theory approach using full potential linear augmented plane wave method, were performed to investigate both electronic and magnetic properties of the MnFe2O4. The high temperatures series expansion (HTSE) is used to study the magnetic properties of MnFe2O4. Findings The saturation magnetization, the coercivity and the transition temperature varied between 21-43 emu/g, 20-50 Oe and 571-630 K, respectively, have been studied. The gap energy of MnFe2O4 has been deduced. The critical temperature and the critical exponent have been obtained using HTSEs. Originality/value In the present work, the authors study the electronic and magnetic properties of MnFe2O4. The results obtained by the experiment and by ab initio calculations were used in HTSE as input to deduce other physical parameters.

Structural and Magnetic Properties of Mn2NiZ (Z = Ga, In, Sn, Sb) Heusler Alloys from Ab Initio Calculations

2015 ◽  
Vol 233-234 ◽  
pp. 229-232 ◽  
Author(s):  
Vladimir V. Sokolovskiy ◽  
Mikhail A. Zagrebin ◽  
Y.A. Sokolovskaya ◽  
Vasiliy D. Buchelnikov
Keyword(s):  
Magnetic Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Heusler Alloys ◽  
Martensitic Transition ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Structural And Magnetic Properties ◽  
Structure Calculations ◽  
Good Agreement

The structural and magnetic properties of Mn-based stoichiometric Heusler alloys have investigated by means of ab initio calculations in framework of the density functional theory. First principles electronic structure calculations have shown that Mn2NiZ (Z = Ga, In, Sn, Sb) alloys are ferrimagnets with antiparallel alignment between the Mn atoms. The martensitic transition can be realized in Mn2NiGa and Mn2NiSn alloys with tetragonal ratio of 1.27 and 1.16, respectively. Calculated properties are in a good agreement with available experimental data.

THEORETICAL MODELS FOR MAGNETIC PROPERTIES OF IRON PNICTIDES

2013 ◽  
Vol 27 (16) ◽  
pp. 1350071 ◽  
Author(s):  
M. VUJINOVIĆ ◽  
M. PANTIĆ ◽  
D. KAPOR ◽  
P. MALI
Keyword(s):  
Magnetic Properties ◽  
Heisenberg Model ◽  
Degrees Of Freedom ◽  
Random Phase ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Wave Dispersion ◽  
Model Parameters ◽  
Neel Temperature ◽  
Néel Temperature

We attempt to describe the magnetic properties of parent pnictide compounds by using both the J1–J2 Heisenberg model and its three-dimensional generalization, the J1–J2–Jc model. We also include spin anisotropy in the XY plane. In order to obtain the average magnetization and spin wave dispersion, we use the Green's functions method for spin operators in the random phase approximation. We obtain estimates for the model parameters by considering the low temperature experimental dispersion for the compounds CaFe 2 As 2 and BaFe 2 As 2 and conclude that theoretical dispersion can fit the experimental one if spatially anisotropic Hamiltonian is used. A good agreement between theory and experiment indicates that the Heisenberg model is applicable to parent pnictides at low temperatures. The applicability of the model for higher temperatures is checked by calculating the Néel temperature for both compounds. It turns out that the model overestimates the measured critical temperature. The Heisenberg model is not applicable to parent pnictides, for temperature comparable to Néel temperature. Our results thus confirm that all the magnetic properties of parent pnictides cannot be described with purely localized degrees of freedom, and that the itinerant magnetism should have an important role in these compounds. All results given in Sec. 3 are general and could be used in description of classes of compounds with spin stripe structure.

Effect of thermal aging on the Néel temperature of a Fe–Cr–Ni–Mo alloy

2002 ◽  
Vol 17 (4) ◽  
pp. 879-883 ◽  
Author(s):  
C. H. Shek ◽  
M. W. Lai ◽  
J. K. L. Lai
Keyword(s):  
Magnetic Properties ◽  
Thermal Aging ◽  
Magnetic Transition ◽  
Neel Temperature ◽  
Néel Temperature ◽  
Detailed Mechanism

Numerous previous investigations on the magnetic properties of Fe–Cr–Ni or similar alloys show that the Néel temperature of this class of material is usually in the range 20–40 K and never exceeds 60 K. In this paper, we report on the discovery that the Ne’el temperature of a Fe–Cr–Ni–Mo alloy can be substantially increased to approximately 80–100 K by long-term thermal aging at 800 °C and above. This discovery has raised many questions on the detailed mechanism of magnetic transition on this class of material and is expected to open up a new line of investigation for researchers in this field.

scholarly journals Магнитные свойства двухфазных магнитных боросиликатных стекол, содержащих наночастицы beta-Fe-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- и Fe-=SUB=-3-=/SUB=-O-=SUB=-4-=/SUB=-

2020 ◽  
Vol 46 (16) ◽  
pp. 28
Author(s):  
С.А. Борисов ◽  
А.А. Набережнов ◽  
B. Nacke ◽  
A. Nikanorov
Keyword(s):  
Magnetic Properties ◽  
Magnetic Fields ◽  
Fe3o4 Nanoparticles ◽  
Superparamagnetic Nanoparticles ◽  
Blocking Temperature ◽  
Neel Temperature ◽  
Specific Magnetization ◽  
Borosilicate Glasses ◽  
Néel Temperature ◽  
Two Phase

The magnetic properties of two-phase borosilicate glasses containing in the skeleton a mixture of β-Fe2O3 and Fe3O4 nanoparticles have been studied. The sizes of nanoparticles have been determined, the value of blocking temperature (TB ~ 330 K) for ensemble of superparamagnetic nanoparticles is obtained. It is shown that in the high applied magnetic fields the specific magnetization of these glasses increases sharply at approaching and below Neel temperature for the bulk β-Fe2O3.

Ab-initio DFT simulation of electronic and magnetic properties of Tin+1and FeTin clusters

2021 ◽  
Author(s):  
Rachida Haichour ◽  
Sofiane MAHTOUT
Keyword(s):  
Magnetic Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Three Dimensional ◽  
Binding Energies ◽  
Chemical Hardness ◽  
Generalized Gradient ◽  
Cage Structure ◽  
Electronic And Magnetic Properties ◽  
The Stability

Abstract We report a computational investigation of the electronic and magnetic properties of neutral Tin+1and FeTin (n=1-10) clusters using ab-initio calculations based on density functional theory (DFT) within the generalized gradient approximation (GGA). The best structures for Tin+1and FeTin clusters are planar for size n<5, while from n = 5, they showed a compact three dimensional cage structure. For the best structures of the FeTin clusters, the Fe atoms favors the peripheral position with highest coordination with the neighboring Ti atoms. The evolution as a function of the size of the average binding energies (Eb/atom) and HOMO–LUMO gaps of Tin+1 and FeTin (n=1-10) clusters are studied. The stability results show that the Tin+1 clusters have relatively higher stability than the FeTin cluster with the same size. In addition, the vertical ionization potentials and electron affinities, chemical hardness and atomic magnetic moment of Tin+1and FeTin (n=1-10) clusters are also investigated.

Theoretical Study on Ni2XIn (X=Mn, Fe and Co) Magnetic Shape Memory Alloys by Ab Initio Calculations

2013 ◽  
Vol 712-715 ◽  
pp. 288-292 ◽  
Author(s):  
Jing Bai ◽  
Jiang Long Gu ◽  
Wen Qi Liu ◽  
Xin Wang ◽  
Yan Ming Wang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Ab Initio ◽  
Density Functional ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Austenitic Phase ◽  
Electronic Density ◽  
Functional Theory

The crystallographic, magnetic and electronic structures of the magnetic shape memory alloys Ni2XIn (X=Mn, Fe and Co) are systematically investigated by means of theab initiocalculations within the framework of density functional theory. The equilibrium lattice parameters and the bulk modulus of the austenitic phase in Ni2XIn are systematically calculated. The formation energy of the L21phase of the Ni2XIn is estimated, and displays a destabilization tendency if Mn atom is substituted by Fe or Co. Furthermore, the magnetic properties of the Ni2XIn have been investigated, and the essence of the variation in the magnetic properties with the X atomic number has been illustrated from the view of the electronic density of states.

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