Value Of Magnetic Moment Research Articles

Effect of structural defects on the magnetic properties of the EuBaCo1.90O5.36 single crystal

The effect of structural defects in cobalt and oxygen sublattices with the constant average oxidation level 3+ of all cobalt ions on the magnetic properties of the EuBaCo1.90O5.36 single crystal has been studied. The magnetic properties of the single crystal and the polycrystalline sample of the corresponding composition are compared in the range T = 200–650 K. The results show that the cobalt-deficient EuBaCo2–x O5.5–δ samples demonstrate a three-dimensional XY ferromagnetic ordering of magnetic sublattices. The values of the effective magnetic moment at T > 480 K indicate the existence of the IS and HS states of Co3+ ions. The large difference of values of μeff of the EuBaCo1.90O5.36 single crystal and polycrystal can be due to that the magnetic ion spins lie in plane ab. The magnetic field directed along plane ab substantially influences the magnetic ordering at T < 300 K.

Влияние структурных дефектов на магнитные свойства монокристалла EuBaCo-=SUB=-1.90-=/SUB=-O-=SUB=-5.36-=/SUB=-

AbstractThe effect of structural defects in cobalt and oxygen sublattices with the constant average oxidation level 3+ of all cobalt ions on the magnetic properties of the EuBaCo_1.90O_5.36 single crystal has been studied. The magnetic properties of the single crystal and the polycrystalline sample of the corresponding composition are compared in the range T = 200–650 K. The results show that the cobalt-deficient EuBaCo_2– x O_5.5–δ samples demonstrate a three-dimensional XY ferromagnetic ordering of magnetic sublattices. The values of the effective magnetic moment at T &gt; 480 K indicate the existence of the IS and HS states of Co^3+ ions. The large difference of values of μ_eff of the EuBaCo_1.90O_5.36 single crystal and polycrystal can be due to that the magnetic ion spins lie in plane ab. The magnetic field directed along plane ab substantially influences the magnetic ordering at T &lt; 300 K.

Measurement of hadronic cross sections with BABAR

The BABAR Collaboration pursues an intensive program studying hadronic cross sections in low-energy electron-positron annihilations, accessible via initial-state radiation. Our measurements allow significant improvements in the precision of the predicted value of the muon anomalous magnetic moment. These improvements are necessary for shedding light on the current 3 σ difference between the predicted and the experimental values. We have published results on a number of processes with from two to six hadrons in the final state and other final states are currently under investigation. We report here on the most recent results obtained by analysing the entire BABAR dataset. We present in particular the measurement of the mode with two charged pions and two neutral pions and the measurement of the full set of final states with two kaons and one or two pions.

Электронная структура интерметаллического соединения GdCuGe

AbstractThe electronic structure of GdCuGe intermetallic compound has been studied. Spin-polarized energy spectrum calculations have been performed by the band method with allowance for strong electron correlations in the 4 f -shell of gadolinium ions. Antiferromagnetic ordering of GdCuGe at low temperatures has been obtained in a theoretical calculation, with the value of the effective magnetic moment of gadolinium ions reproduced in fair agreement with experimental data. The electronic density of states has been analyzed. An optical conductivity spectrum has been calculated for GdCuGe; it reveals specific features that are analogous to the ones discovered previously in the GdCuSi compound with a similar hexagonal structure.

Electron paramagnetic resonance and magnetic properties of α-BiNb1−xFexO4−δ

Iron-containing ceramic materials based on BiNbO4 of orthorhombic modification were obtained by solid-phase synthesis. The solid solutions α-BiNb1-xFexO4-δ were synthesized of х ≤ 0.03. The single-phase structure of these samples was established by X-ray diffraction and SEM- analyses. In the EPR spectra of BiNb1-xFexO4-δ, a wide band with a center at g = 2.16–2.37 were observed, which had a low-intensity signal with a g-factor of ~ 4.3 on the low-field wing. Along with the broad spectrum component, a "noise-like" signal was observed in the magnetic field range of 190-400 mT, which was formed by a large number of narrow lines related to the integral signal of ferromagnetic resonance and its fine structure. The isotherms of the paramagnetic component of the magnetic susceptibility of iron atoms in BiNb1-xFexO4-δ are typical for antiferromagnets. The value of the effective magnetic moment of iron atoms increases along with the increase in temperature from 5.84 MB (90 K) to 6.43 MB (320 K). This can be explained by the presence of exchange-bound aggregates of Fe (III) atoms with the antiferro- and ferromagnetic types of exchange in the solid solutions. Magnetic behavior of BiNb1-xFexO4-δ was investigated taking into account the presence of possible types of clusters of iron atoms by theoretical calculation of the magnetic susceptibility within the framework of the model of dilute solid solutions. The best agreement between the experimental and calculated data was obtained for the dimer parameters of Jdim - 17 cm-1 and Jdim 45 cm-1, for antiferro-and ferromagnetic type of exchange.

On verifying magnetic dipole moment of a magnetic torquer by experiments

Magnetic torquers are used for the attitude control of small satellites, such as CubeSats with Low Earth Orbit (LEO). During the design of magnetic torquers, it is necessary to confirm if its magnetic dipole moment is enough to control the satellite attitude. The magnetic dipole moment can affect the detumbling time and the satellite rotation time. In addition, it is also necessary to understand how to design the magnetic torquer for operation in a CubeSat under the space environment at LEO. This paper reports an investigation of the magnetic dipole moment and the magnetic field generated by a circular air-coil magnetic torquer using experimental measurements. The experiment testbed was built on an air-bearing under a magnetic field generated by a Helmholtz coil. This paper also describes the procedure to determine and verify the magnetic dipole moment value of the designed circular air-core magnetic torquer. The experimental results are compared with the design calculations. According to the comparison results, the designed magnetic torquer reaches the required magnetic dipole moment. This designed magnetic torquer will be applied to the attitude control systems of a 1U CubeSat satellite in the project “KNACKSAT.”

Density functional theory of InCn+(n=110) clusters

Small indium-doped carbon clusters InCn+(n=110) are systematically studied by the density functional theory at the B3 LYP/LANL2 DZ level. The computed properties include equilibrium geometries, electronic energies, vibrational frequencies, dipole moments and rotational constants for individual species. The calculation results show that the open-chain linear isomers with the indium atom bound to the end of the carbon chain are the most stable geometry in all cases. There must exist a cyclic or fan structure in the metastable or the third stable structure of cluster. The bigger the size of the cluster, the more obvious the stability of the structure is. The electronic ground state is found to be alternately a triplet for even n and a singlet for odd n with the only exception of InC+. It is generally observed that the spin contamination is not serious for all electronic ground states because the s2 values are uniform and in general deviate slightly from the pure spin values, and the B3 LYP wave functions are nearly spin-pure. It is also found that in the lowest-energy linear structure, the InC bond is longer (from 2.319 to 2.850 ) than the corresponding CC bonds in a range from 1.268 to 1.360 . The CC distances can be assimilated to moderately strong double bonds underlying a clear bonding in the corresponding structures. In addition, we observe a clear alternation in CC distances. The CoddCeven distances are shorter than the CevenCodd ones which mainly results from the charge distribution and spin density. According to the calculation and analysis of the incremental binding energy and the second difference we can deduce an even-odd alternation in the cluster stability for the linear InCn+, with their n-odd members being more stable than the adjacent even-numbered ones. This parity effect also appears in the adiabatic ionization potential curves. The analysis of magnetic properties shows the even-odd alternation with n-even clusters presenting higher values of magnetic moment than n-odd ones. The study of the polarizability indicates that the average values of both the polarization tensors and the anisotropic invariants increase with the size of cluster increasing.

Predictions of thermomagnetic properties of Laves phase compounds: TbAl2, GdAl2 and SmAl2 performed with ATOMIC MATTERS MFA computation system

Recent calculations of properties of TbAl2 GdAl2 and SmAl2 single crystals, performed with our new computation system called ATOMIC MATTERS MFA are presented. We applied localized electron approach to describe the thermal evolution of Fine Electronic Structure of Tb3+, Gd3+ and Sm3+ ions over a wide temperature range and estimate Magnetocaloric Effect (MCE). Thermomagnetic properties of TbAl2, GdAl2 and SmAl2 were calculated based on the fine electronic structure of the 4f8, 4f7 and 4f5 electronic configuration of the Tb3+ and Gd3+ and Sm3+ ions, respectively. Our calculations yielded: magnetic moment value and direction; single-crystalline magnetization curves in zero field and in external magnetic field applied in various directions m(T,Bext); the 4f-electronic components of specific heat c4f(T,Bext); and temperature dependence of the magnetic entropy and isothermal entropy change with external magnetic field – ΔS(T,Bext). The cubic universal CEF parameters values used for all CEF calculations was taken from literature and recalculated for universal cubic parameters set for the RAl2 series: A4 = +7.164 Ka04 and A6 = −1.038 Ka06. Magnetic properties were found to be anisotropic due to cubic Laves phase C15 crystal structure symmetry. These studies reveal the importance of multipolar charge interactions when describing thermomagnetic properties of real 4f electronic systems and the effectiveness of an applied self-consistent molecular field in calculations for magnetic phase transition simulation.

Spectral, magnetic, thermal, antioxidant and biological studies on new mixed ligand complexes

In this study, new mixed ligand complexes have been synthesized from bis(2,4,4-trimethylpentyl)dithiophosphinic acid (C16H35PS2) and 1,10-phenanthroline (C12H8N2) with various metal(II) ions. The molecular formula of the metal complexes were [Mn(C16H34PS2)(C12H8N2)] (1), [Fe(C16H34PS2)(C12H8N2)] (2), [Ni(C16H34PS2)(C12H8N2)] (3), [Zn(C16H34PS2)(C12H8N2)] (4) and [Cd(C16H34PS2)(C12H8N2)] (5). These complexes have been characterized by various physico-chemical techniques such as melting point, molar conductance, magnetic susceptibility measurements as well as UV–vis, IR, TG and mass spectroscopic analyses. The surface morphology was determined by scanning electron microscope (SEM). The magnetic moment value, color as well as spectral measurements suggested that the geometrical structures of the metal complexes were tetrahedral. The spectral data showed that bis(2,4,4-trimethylpentyl)dithiophosphinic acid and 1,10-phenanthroline ligands acted as uninegative and neutral bidentate ligand, respectively. They also coordinated with metal(II) ion through two sulfur and two nitrogen atoms. The obtained mixed ligand complexes were more stable in air and highly soluble in common organic solvent. The bio-efficacy of ligands and metal complexes have been screened against the test microorganism using agar disc diffusion method. The biological activity results of metal complexes showed that complex 4 displayed potential antibacterial activity against Clostridium botulinum as compared to the standard drug, imipenem. The complex 2 and 4 were found to have better scavenging activity against 2,2-diphenyl-1-picrylhydrazyl.

First-Principles Investigation of Ferromagnetic, Thermodynamic, Elastic, and Half-Metallic Behavior of ReCrTe and RuCrTe Half-Heusler Alloys

Calculations are realized within the full-potential linearized augmented plane wave (FP-LAPW) computational approach with the generalized gradient approximation (GGA) for the exchange-correlation potential. In this work, we present investigation of structural, electronic, ferromagnetic, elastic, and thermodynamic properties and half-metallic behavior of ReCrTe and RuCrTe compounds. Analysis of band structures and densities of states show the half-metallic ferromagnetic behavior of these compounds. The values of total magnetic moments µtot are 1 µB per unit cell for ReCrTe and 3 µB per unit cell for RuCrTe. The contribution of Cr is the most important. The calculated values of a total magnetic moment nicely follow the rule µtot = Z t− 18. The study of the impacts of strains on the magnetic moment reveals that the two compounds are stable ferromagnetic compounds. RuCrTe compound preserves the half-metallic behavior when the unit cell volume is changed in the range of [ − 4%, 4%], whereas, weak strain destroys the half metallic nature for ReCrTe compound. Using the quasi-harmonic Debye model, the effects of pressure P and temperature T on thermal expansion coefficient, Debye temperature, heat capacity and Gruneisen parameter for these two compounds are investigated for the first time. The study of the elastic constants shows that ReCrTe and RuCrTe are mechanically stable. RuCrTe is stiffer than ReCrTe compounds. The obtained values of Pugh’s ratio B/G and Cauchy pressure (C 12 − C 44) reveal that ReCrTe and RuCrTe are brittle. The study of the electron charge density and Poisson’s ratio proves that the ionic character dominates the atomic bonding for the two compounds.

Ab Initio Theoretical Prediction of Structural, Electronic, and Magnetic Properties in the 3d (Mn)-Doped Zinc-Blende MgSe: A DFT-mBJ Approach

In this paper, we have investigated the structural, electronic, and magnetic properties of magnesium selenium (MgSe) doped with transition metal manganese (Mn) impurity in the cubic diluted magnetic semiconductor (DMS) zinc blende structure. The compounds which we are interested are as Mg1−x Mn x Se where x change between 0 and 1 by step 0.25. All properties are studied, using first-principles calculation of density functional theory under the framework of the full-potential linearized augmented plane waver (FP-LAPW). In our study, we employed the Wu-Cohen generalized approximation (WC-GGA) to optimize the crystal structure, whereas Tran-Blaha modified Becke-Johnson potential (TB-mBJ) as a new functional was applied to compute the electronic and magnetic properties in order to get some better degree of precision. The electronic band structures and density of state plots reveal ferromagnetic semiconducting behavior in these compounds, and the exchange constants N 0 α and N 0 β are calculated to validate the effects resulting from exchange splitting process. Moreover, for each concentration x, the value of total magnetic moment has been estimated to equal to 5 μ B. The important magnetic moments values obtained in these compounds indicate the potential for their use in spintronic devices.

Efficient one-pot sonochemical synthesis of thickness-controlled silica-coated superparamagnetic iron oxide (Fe3O4/SiO2) nanospheres

A facile and eco-friendly efficient sonochemical approach was designed for the synthesis of highly crystalline Fe3O4 and Fe3O4/SiO2 core/shell nanospheres in single reaction. The generated physical properties (shock waves, microjets, and turbulent flows) from ultrasonication as a consequence of the collapse of microbubbles and polyvinylpyrrolidone (PVP) as a chemical linker were found to play a crucial role in the successful formation of the core/shell NPs within short time than the previously reported methods. Transmission electron microscopy revealed that a uniform SiO2 shell is successfully coated over Fe3O4 nanospheres, and the thickness of the silica shell could be easily controlled in the range from 5 to 15 nm by adjusting the reaction parameters. X-ray diffraction data were employed to confirm the formation of highly crystalline and pure phase of a cubic inverse spinel structure for magnetite (Fe3O4) nanospheres. The magnetic properties of the as-synthesized Fe3O4 and Fe3O4/SiO2 core/shell nanospheres were measured at room temperature using vibrating sample magnetometer, and the results demonstrated a high magnetic moment values with superparamagnetic properties.

Quantum mechanical calculation of electron spin

Abstract The classical and quantum mechanical methods are used respectively to calculate the electron spin. It is shown that the classical method cannot derive the correct magnetic moment value. Assuming that the rest energy of the electron originates from the kinetic energy of the virtual particles, the electron spin motion equation and spin wave function can be derived. In the case of the quantum numbers of spin angular momentum and magnetic moment being 1/2 and 1 respectively, their correct values can be obtained. In the meanwhile, the anomalous magnetic moment is evaluated based on the wave function of the spinning electron. Suppose the probability of virtual photons converting into electron-positron pairs to be 0.00141, the result agrees with that of quantum electrodynamics. Given that the energy of the virtual photon obeys the classical Maxwell-Boltzmann distribution, the self-energy of the electron will be finite. In addition, the hierarchy problem can be solved with the same hypothesis.

XPS spectra, electronic structure, and magnetic properties of RFe5Al7 intermetallics

The results of X-ray photoelectron spectroscopy measurements (core levels and valence bands) of RFe5Al7 (R = Lu, Tm, Er, Ho, Dy, Tb, Gd) single crystals are presented in comparison with the results of bulk magnetization studies and electronic structure calculations. It is shown that the increase of the Curie temperature in RFe5Al7 from Tm to Gd is associated with an increase of the indirect R 4f – Fe 3d exchange interaction at the expense of the multiplicity 2S + 1 (statistical weight) in the ground state 2S+1LJ of R3+ ions. The nonmonotonic behavior of the ferrimagnetic compensation temperature, Tcomp, as well as the values of the spontaneous magnetic moment, Ms, and formation energy, Eform, of the 4fn levels in R metals in a series from ErFe5Al7 to GdFe5Al7 are explained by the difference in the quantum numbers L, J and S of the ground state of R3+ ions, leading to a maximum value of Tcomp, Ms and Eform for the Dy-containing compound. The electronic structure of Gd/LuFe5Al7 is calculated using the GGA+U approach, on the basis of which the physical mechanism and relative strength of the interatomic R-Fe and Al-Fe interactions are considered, and also the difference in the magnetic moments of iron atoms in different structural positions is explained.

Earth’s magnetic moment during geomagnetic reversals

The behavior of the dipole magnetic moment of the geomagnetic field during the reversals is considered. By analogy with the reversals of the magnetic field of the Sun, the scenario is suggested in which during the reversal the mean dipole moment becomes zero, whereas the instantaneous value of the dipole magnetic moment remains nonzero and the corresponding vector rotates from the vicinity of one geographical pole to the other. A thorough discussion concerning the definition of the mean magnetic moment, which is used in this concept, is presented. Since the behavior of the geomagnetic field during the reversal is far from stationary, the ensemble average instead of the time average has to be considered.

First principle calculations of electronic and magnetic properties of Mn-doped CdS (zinc blende): a theoretical study

AbstractThe electronic structure and magnetic properties of Mn doped zinc blende cadmium sulfide Cd1-xMnxS (x = 6.25 %) have been studied using spin-polarized density functional theory within the framework of Generalized Gradient Approximation (GGA), its further corrections including Hubbard U interactions (GGA + U) and a model for exchange and correlation potential Tran Blaha modified Becke-Johnson (TB-mBJ). Ferromagnetic interactions have been observed between Mn atoms via S atom due to strong p-d hybridization. The magnetic moments on Mn and its neighboring atoms have also been studied in detail using different charge analysis techniques. It has been observed that p-d hybridization reduced the value of local magnetic moment of Mn in comparison to its free space charge value and produced small local magnetic moments on the nonmagnetic S and Cd host sites. The magnetocrystalline anisotropy in [1 0 0] and [1 1 1] directions as well as exchange splitting parameters Noα and Noβ have been analyzed to confirm that ferromagnetism exists. We conclude that the ferromagnetic phase in Mn-doped CdS is not stable in “near” configuration but it is stable for “far” configuration. Mn doped CdS is a p-type semiconductor and the d-states at the top of the valence band edge give a very useful material for photoluminescence and magneto-optical devices.

Reconsidering the one leptoquark solution: flavor anomalies and neutrino mass

We reconsider a model introducing a scalar leptoquark ϕ ∼ (3,1, −1/3) to explain recent deviations from the standard model in semileptonic B decays. The leptoquark can accommodate the persistent tension in the decays overline{B}to {D}^{left(ast right)}tau overline{nu} as long as its mass is lower than approximately 10 TeV, and we show that a sizeable Yukawa coupling to the right-chiral tau lepton is necessary for an acceptable explanation. A characteristic prediction of this scenario is a value of {R}_{D^{*}} slightly smaller than the current world average. Agreement with the measured overline{B}to {D}^{left(ast right)}tau overline{nu} rates is mildly compromised for parameter choices addressing the tensions in b → sμμ, where the model can significantly reduce the discrepancies in angular observables, branching ratios and the lepton-flavor-universality observables RK and {R}_{K^{*}} . The leptoquark can also reconcile the predicted and measured value of the anomalous magnetic moment of the muon and appears naturally in models of radiative neutrino mass derived from lepton-number violating effective operators. As a representative example, we incorporate the particle into an existing two-loop neutrino mass scenario derived from a dimension-nine operator. In this specific model, the structure of the neutrino mass matrix provides enough freedom to explain the small masses of the neutrinos in the region of parameter space dictated by agreement with the anomalies in overline{B}to {D}^{left(ast right)}tau overline{nu} , but not the b → s transition. This is achieved without excessive fine-tuning in the parameters important for neutrino mass.

Oxide Based Dilute Magnetic Semiconductor- A Brief Review

Dilute magnetic semiconductors (DMS) play an important role in interdisciplinary materials science. Out of this oxygen based DMS this system has been the subject of intense research for Enhancement of magnetic property as well as the Curie temperature. In this system the charge and spin degrees of freedom are accommodated into single matter and their interplay is expected to explore novel physics and new devices. Rare earth oxides have become a interesting field of study for their interesting properties as well as their versatile applications in different fields. Recently the various physical properties, viz., optical (absorption spectra, IR spectra, Raman spectra), magnetic, thermal and hyperfine properties of rare earth oxides have been reported. The various 3d transition metal ion (e.g., Fe, Ni, Co etc) which has also high value of magnetic moment, has been doped in different rare earth oxides, in recent years and it is reported that there is an enhancement in the magnetization. Doping of 3-d metal ion in different rare earth oxide and other semiconducting oxide system can be interesting for the enhancement of magnetization. From the viewpoint of DMS, there may be strong ferromagnetic exchange coupling between localized spins due to carrier induced ferromagnetism and double exchange interaction when localized spin is introduced in the oxide semiconductor.

Effect of samarium doping on structural, optical and magnetic properties of vertically aligned ZnO nanorod arrays

Samarium doped vertically aligned one dimensional ZnO nanorod (NR) arrays were grown by vapor phase transport (VPT) method through vapor solid (VS) growth process. Influence of different concentrations (0% to 8%) of Sm (all Sm contents in the paper are in mass fraction) on the ZnO NR arrays were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL), Raman spectroscopy and vibrating sample magnetometry (VSM) techniques, respectively. X-ray diffraction studies revealed that the ZnO NR arrays were perfectly oriented along (002) crystallographic orientation with wurtzite crystal structure. Photoluminescence results showed an increase in oxygen vacancies due to increase in Sm doping. M-H curves revealed enhanced ferromagnetic behavior, and the magnetic moment values were 0.45, 0.363, 1.694, 3.613 and 2.197 emu/cm3 for (0–8%) Sm doped ZnO NR arrays respectively. The curve revealed that paramagnetic behavior was observed for undoped ZnO NR arrays and on increasing the Sm dopant to 4%, paramagnetic switched to ferromagnetic behavior.

Synthesis, characterization and antimicrobial activities of leucine-acetylacetone Schiff base and its Mn(II), Ni(II) and Cu(II) complexes

A Schiff-base derived from leucine and acetylacetone, and its Cu(II), Ni(II) and Mn(II) complexes were synthesized and analyzed based on their melting point/decomposition temperature, solubility, molar conductance, magnetic and infrared analyses. Physical and analytical data suggested that the Schiff base acted as tridentate ligand towards metal ion via azomethine-N, deprotonated-O of carboxylic group and enolic-O group of acetylacetone. All the c mplexes have lower molar conductance values (6.4-17.7Ω-1cm2mol-1), indicating that they are non-electrolyte. The magnetic moment values showed that all the metal ions in the complexes are paramagnetic. The synthesized ligand and its respective metal complexes were screened for their antibacterial activity against Staphylococcus aureus (Gram-positive), Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Klebsiella pneumonia (Gram-negative) and antifungal activity against Candida albicans, Fusarium solani and Aspergillus fumigatus. The results of these studies revealed that the compound (ligand) and its metal complexes showed significant antibacterial and antifungal strength at high concentrations.Keywords: Schiff base, acetylacetone, leucine, antimicrobial activity, Synthesis