scholarly journals OCTET MAGNETIC MOMENTS WITH NULL INSTANTONS AND SEMIBOSONIZED NAMBU–JONA-LASINIO MODEL

1999 ◽  
Vol 14 (36) ◽  
pp. 2525-2529
Author(s):  
ELENA N. BUKINA
Keyword(s):  
Quark Model ◽  
Magnetic Moment ◽  
Magnetic Moments ◽  
Symmetry Properties ◽  
Meson Cloud ◽  
The Difference

It is shown that the difference between the magnetic moment results in the quark model with null instantons and semibosonized Nambu–Jona-Lasinio model lies in the symmetry properties of the meson cloud contributions.

Theoretical Studies on the Magnetic Moments of Iron Nitrides Including Fe16N2

1993 ◽  
Vol 313 ◽  
Author(s):  
Akimasa Sakuma ◽  
Yutaka Sugita
Keyword(s):  
Magnetic Moment ◽  
Density Functional ◽  
Magnetic Moments ◽  
Iron Nitrides ◽  
Functional Formalism ◽  
Orbital Magnetic Moment ◽  
Spin Polarized ◽  
Calculated Magnetic Moment ◽  
The Difference

ABSTRACTThe spin-polarized band calculations for the iron nitrides, Fe3N, Fe4N and Fe16N2, have been performed with use of LMTO-ASA Method in the frame of local spin density functional formalism. The results show that the most distant Fe atoms from N have the largest magnetic moment. The central role of the N atom is to bring about the large magnetic moments through the lattice expansion. Concurrently, the N atoms promote an itinerancy of electrons and then in turn prevent the exchange-splitting. This results in an Fe16N2 with the lowest N concentration having the largest magnetic moments. Quantitatively, the obtained magnetic moments are in fair agreements with the experimental results except for Fe16Nr The calculated magnetic moment of Fe6N2 is about 2.4 ΜB/Pε, while the measured value is reported as 3.5 ΜB/FB. The orbital magnetic moment of Fe16N2 is about 0.07 ΜB, which is too small to make up for the difference from the experimental value.

scholarly journals Isotopic effect of macro- and microelements in ecosystems

2020 ◽  
pp. 132-138
Author(s):  
О. Musich ◽  
A. Zubko ◽  
О. Demyanуuk
Keyword(s):  
Magnetic Moment ◽  
Magnetic Moments ◽  
Chemical Characteristic ◽  
Complex Compounds ◽  
Isotopic Effect ◽  
Biochemical Reactions ◽  
Fundamental Properties ◽  
The Difference ◽  
Living Organisms ◽  
Isotopic Effects

Isotopic effects occurring in living organisms due to metabolism are analyzed. The phenomenon of metabolism is considered in the classical sense as a combination of biochemical reactions (mainly enzyma­tic) that take place in the cells of living beings and provide the cleavage, synthesis and interconversion of complex compounds. The scope of use of natural isotopes is wide and diverse. Isotopes are carriers of information about the birth and transformation of molecules, and isotope fractionation is a chemical characteristic of a substance. Isotope metabolism consists in the intermolecular fractionation of isotopes at separate stages of biochemical reactions, namely the cleavage, synthesis and interconversion of complex compounds caused by differences in the structure and fundamental properties of isotope nuclei. It is proved that the fractionation of isotopes in chemical and biochemical reactions due to isotopic effects is based on two fundamental properties of atomic nuclei — mass and magnetic moment. The kinetic (mass-depen­ dent) isotopic effect distributes the isotopic nuclei by their masses, and the magnetic one fractionates the nuclei by their magnetic moments. The kinetic isotopic effect depends on the magnitude of the difference in the masses of isotopic molecules, temperature and the difference in the activation energies of isotopic forms. The magnetic isotope effect depends on the reaction rate in a single cell, its projection, magnetic moment and energy of electron-nuclear interaction. It is determined that the fractionation of isotopes in living organisms is that the relative content of one of the isotopes in this compound increases by reducing its content in the other. As a result, there is a fractionation of isotopes within one biological object.

scholarly journals Sea Contributions to Spin 1/2 Baryon Structure, Magnetic Moments, and Spin Distribution

1997 ◽  
Vol 12 (10) ◽  
pp. 1861-1874 ◽  
Author(s):  
V. Gupta ◽  
R. Huerta ◽  
G. Sánchez-Colón
Keyword(s):  
Wave Function ◽  
Numerical Analysis ◽  
Quark Model ◽  
Magnetic Moment ◽  
Composite System ◽  
Magnetic Moments ◽  
Spin Distribution ◽  
Quantum Numbers ◽  
Experimental Errors ◽  
Spin Distributions

We treat the baryon as a composite system made out of a "core" of three quarks (as in the standard quark model) surrounded by a "sea" (of gluons and [Formula: see text]-pairs) which is specified by its total quantum numbers like flavor, spin and color. Specifically, we assume the sea to be a flavor octet with spin 0 or 1 but no color. The general wave function for spin 1/2 baryons with such a sea component is given. Application to the magnetic moments is considered. Numerical analysis shows that a scalar (spin 0) sea with an admixture of a vector (spin 1) sea can provide very good fits to the magnetic moment data using experimental errors. These fit also give reasonable values for the spin distributions of the proton and neutron.

scholarly journals Large neutrino magnetic moments in the light of recent experiments

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
K. S. Babu ◽  
Sudip Jana ◽  
Manfred Lindner
Keyword(s):  
Magnetic Moment ◽  
Magnetic Moments ◽  
Spin Symmetry ◽  
Simplified Model ◽  
Transition Magnetic Moment ◽  
Horizontal Symmetry ◽  
Electron Recoil ◽  
Majorana Neutrinos ◽  
The Difference ◽  
Dependent Mass

Abstract The excess in electron recoil events reported recently by the XENON1T experiment may be interpreted as evidence for a sizable transition magnetic moment $$ {\mu}_{v_e{v}_{\mu }} $$ μ v e v μ of Majorana neutrinos. We show the consistency of this scenario when a single component transition magnetic moment takes values $$ {\mu}_{v_e{v}_{\mu }}\in \left(1.65-3.42\right)\times {10}^{-11}{\mu}_B $$ μ v e v μ ∈ 1.65 − 3.42 × 10 − 11 μ B . Such a large value typically leads to unacceptably large neutrino masses. In this paper we show that new leptonic symmetries can solve this problem and demonstrate this with several examples. We first revive and then propose a simplified model based on SU(2)H horizontal symmetry. Owing to the difference in their Lorentz structures, in the SU(2)H symmetric limit, mν vanishes while $$ {\mu}_{v_e{v}_{\mu }} $$ μ v e v μ is nonzero. Our simplified model is based on an approximate SU(2)H, which we also generalize to a three family SU(3)H-symmetry. Collider and low energy tests of these models are analyzed. We have also analyzed implications of the XENON1T data for the Zee model and its extensions which naturally generate a large $$ {\mu}_{v_e{v}_{\mu }} $$ μ v e v μ with suppressed mν via a spin symmetry mechanism, but found that the induced $$ {\mu}_{v_e{v}_{\mu }} $$ μ v e v μ is not large enough to explain recent data. Finally, we suggest a mechanism to evade stringent astrophysical limits on neutrino magnetic moments arising from stellar evolution by inducing a medium-dependent mass for the neutrino.

Baryon magnetic moments in the covariant oscillator quark model with unequal constituent masses

1983 ◽  
Vol 28 (11) ◽  
pp. 2918-2921 ◽  
Author(s):  
Shin Ishida ◽  
Kenji Yamada ◽  
Masuho Oda
Keyword(s):  
Quark Model ◽  
Magnetic Moments

scholarly journals Spin Gapless Semiconductor–Nonmagnetic Semiconductor Transitions in Fe-Doped Ti2CoSi: First-Principle Calculations

2018 ◽  
Vol 8 (11) ◽  
pp. 2200 ◽  
Author(s):  
Yu Feng ◽  
Zhou Cui ◽  
Ming-sheng Wei ◽  
Bo Wu ◽  
Sikander Azam
Keyword(s):  
Magnetic Moment ◽  
Electronic Structures ◽  
Magnetic Moments ◽  
Total Magnetic Moment ◽  
First Principle ◽  
Half Metallic ◽  
Heusler Compound ◽  
First Principle Calculations ◽  
Metallic Ferromagnet

Employing first-principle calculations, we investigated the influence of the impurity, Fe atom, on magnetism and electronic structures of Heusler compound Ti2CoSi, which is a spin gapless semiconductor (SGS). When the impurity, Fe atom, intervened, Ti2CoSi lost its SGS property. As TiA atoms (which locate at (0, 0, 0) site) are completely occupied by Fe, the compound converts to half-metallic ferromagnet (HMF) TiFeCoSi. During this SGS→HMF transition, the total magnetic moment linearly decreases as Fe concentration increases, following the Slate–Pauling rule well. When all Co atoms are substituted by Fe, the compound converts to nonmagnetic semiconductor Fe2TiSi. During this HMF→nonmagnetic semiconductor transition, when Fe concentration y ranges from y = 0.125 to y = 0.625, the magnetic moment of Fe atom is positive and linearly decreases, while those of impurity Fe and TiB (which locate at (0.25, 0.25, 0.25) site) are negative and linearly increase. When the impurity Fe concentration reaches up to y = 1, the magnetic moments of Ti, Fe, and Si return to zero, and the compound is a nonmagnetic semiconductor.

scholarly journals The strangeness magnetic moment of the proton in the chiral quark model

2000 ◽  
Vol 665 (3-4) ◽  
pp. 353-364 ◽  
Author(s):  
L. Hannelius ◽  
D.O. Riska ◽  
L.Ya. Glozman
Keyword(s):  
Quark Model ◽  
Magnetic Moment ◽  
Chiral Quark Model

scholarly journals Origin of the Low Magnetic Moment in Fe2AlTi: An Ab Initio Study

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1732 ◽  
Author(s):  
Martin Friák ◽  
Anton Slávik ◽  
Ivana Miháliková ◽  
David Holec ◽  
Monika Všianská ◽  
...  
Keyword(s):  
Ab Initio ◽  
Magnetic Moment ◽  
Energy Surface ◽  
Magnetic Moments ◽  
Local Magnetic Moment ◽  
Spin Configuration ◽  
Spin Effects ◽  
Order Of Magnitude ◽  
Huge Impact ◽  
Insight Into

The intermetallic compound Fe 2 AlTi (alternatively Fe 2 TiAl) is an important phase in the ternary Fe-Al-Ti phase diagram. Previous theoretical studies showed a large discrepancy of approximately an order of magnitude between the ab initio computed magnetic moments and the experimentally measured ones. To unravel the source of this discrepancy, we analyze how various mechanisms present in realistic materials such as residual strain effects or deviations from stoichiometry affect magnetism. Since in spin-unconstrained calculations the system always evolves to the spin configuration which represents a local or global minimum in the total energy surface, finite temperature spin effects are not well described. We therefore turn the investigation around and use constrained spin calculations, fixing the global magnetic moment. This approach provides direct insight into local and global energy minima (reflecting metastable and stable spin phases) as well as the curvature of the energy surface, which correlates with the magnetic entropy and thus the magnetic configuration space accessible at finite temperatures. Based on this approach, we show that deviations from stoichiometry have a huge impact on the local magnetic moment and can explain the experimentally observed low magnetic moments.

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