Units Of Bohr Magneton Research Articles

First principles study of d0-d half-Heusler alloys containing group-IV, -V, and -VI sp atoms as prospective half-metals for real spintronic applications

Employing the full-potential linearized augmented plane-wave method in framework of the density functional theory, the electronic structure, magnetism, structural stability, and half-metallicity of 420 XYZ d0-d half-Heusler alloys composed of d0 alkali metals X = K, Rb, Cs; 3d transition-metals Y = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn; and group-IV, -V, and -VI elements Z = C, Si, Ge, Sn, Pb, N, P, As, Sb, Bi, O, S, Se, Te are systematically investigated with a goal of identifying compounds of interest for spintronic devices. The calculations led to the introduction of eighty nine new robust half-metallic ferromagnetic compounds with half-metallic gaps in the range 0.04–1.12 eV (within GGA) at the corresponding optimized lattice constants and atomic arrangements. The robustness of these half-metallic gaps against uniform and uniaxial strains are tested. The calculated total spin magnetic moments of all half-metallic structures were integer quantities in units of Bohr magneton, in agreement with either Slater-Pauling rule Mt = (Zt − 8) or Mt = (Zt − 18). It is estimated using Monte Carlo simulations that the Curie temperatures of the half metals, in most cases, are notably higher than the room-temperature. To study the thermodynamic and mechanical (dynamic) phase stability of these half-metallic structures at ambient conditions, the convex hull construction and elastic constants analysis have been employed, respectively. These considerations reveal that many of the d0-d half-metallic structures introduced here may be grown epitaxially under appropriate conditions for real spintronic applications.

Investigation of the electronic, magnetic, elastic, thermodynamic and thermoelectric properties of Mn2CoCr Heusler compound: A DFT-based simulation

Heusler compounds have been promising materials for their applications in spintronic, memory and thermoelectric devices. The Mn2CoCr, a full Heusler compound, has been investigated here for its mechanical, thermodynamic and thermoelectric prospective for the first time using full potential linearized augmented plane wave (FP-LAPW) method in support of density functional theory (DFT). The estimation of total energy conferred to Fm-3m structure in ferromagnetic phase, which was in accordance to the others finding. The estimated total magnetic moment was found to be 5.02 (in the units of Bohr magneton), which was in accordance with the Pauling-Slater rule and available data. The electronic structure using generalized gradient approximation (GGA) and modified Becke-Johnson (mBJ) revealed its metallic nature in both the spin configurations. Further, we have calculated the thermodynamic and thermoelectric constants such as specific heat, Debye temperature, Gruneisen constant, thermal conductivity, Seebeck coefficient and power factor. Our predicted value of specific heat at constant volume is 66.6 J/mol.K at 300 K and 0 GPa, which at higher temperature (1000 K) followed Dulong-Petit limit. The power factor was calculated to be 25x1012 Wm-1K−2 at 500 K, demonstrating its suitability in thermoelectric applications.

Ferromagnetic Half-Semiconductor (HSC) gaps in co-doped CdS: Ab-initio study

In this work we have used the density functional theory (DFT) to study structural, magnetic and electronic properties of Co doped CdS in the zinc-blende (ZB) phase. Three approximations have been used to treat the exchange-correlation potential: the (PBE) GGA, (PBE) GGA+U and the model of Tran–Blaha modified Becke–Johnson potential (TB-mBJ). The on–site Coulomb interaction correction given by the Hubbard U has been calculated by the local density approximation constraint for the Co electronic orbitals. The theoretical results show that all the properties under study are affected by the doping of Co atom. Co doped CdS becomes a Ferromagnetic Half-Semiconductors (HSC). The total magnetic moment increases with increasing Co concentration; reaching the value of 9 (in the units of Bohr magneton) at high concentration (x = 18.75 %). The total magnetic moment value is an integer in the GGA+U and TB-mBJ approximations. Furthermore, to validate the effects resulting from the exchange splitting process, we have calculated the values of the spin-exchange constants N0α and N0β, respectively. All these changes make CdS:Co extremely interesting system for the spintronic applications.

Transition magnetic moments of Majorana neutrinos in supersymmetry withoutR-parity in light of neutrino oscillations

The transition magnetic moments of Majorana neutrinos ${\ensuremath{\mu}}_{{\ensuremath{\nu}}_{ij}}$ ($ij=e\ensuremath{\mu}$, $e\ensuremath{\tau}$, $\ensuremath{\mu}\ensuremath{\tau}$) are calculated in grand unified theory (GUT) constrained Minimal Supersymmetric Standard Model (MSSM) with explicit $R$-parity violation. It is assumed that neutrinos acquire masses via one-loop (quark-squark and lepton-slepton) radiative corrections. The mixing of squarks, sleptons, and quarks is considered explicitly. The connection between ${\ensuremath{\mu}}_{{\ensuremath{\nu}}_{ij}}$ and the entries of neutrino mass matrix is studied. The current upper limits on ${\ensuremath{\mu}}_{{\ensuremath{\nu}}_{ij}}$ are deduced from the elements of phenomenological neutrino mass matrix, which is reconstructed using the neutrino oscillation data and the lower bound on the neutrinoless double beta decay half-life. Further, the results for ${\ensuremath{\mu}}_{{\ensuremath{\nu}}_{e\ensuremath{\mu}}}$, ${\ensuremath{\mu}}_{{\ensuremath{\nu}}_{e\ensuremath{\tau}}}$ and ${\ensuremath{\mu}}_{{\ensuremath{\nu}}_{\ensuremath{\mu}\ensuremath{\tau}}}$ are presented for the cases of inverted and normal hierarchy of neutrino masses and different SUSY scenarios. The largest values are of the order of ${10}^{\ensuremath{-}17}$ in units of Bohr magneton.

Constraints on Dirac-type neutrino magnetic moments from 37Cl and Kamiokande II solar-neutrino observations.

The different time variations of solar-neutrino observations in the $^{37}\mathrm{Cl}$ and Kamiokande II experiments are accounted for by postulating a sizable contribution from an additional electromagnetic interaction via a neutrino magnetic moment in the Kamiokande II detector. Based on the combined effects of weak and electromagnetic interactions of neutrinos, this discrepancy in the time variation provides a range of allowed values for a Dirac-type neutrino magnetic moment, $4.0l{\ensuremath{\mu}}_{{\ensuremath{\nu}}_{e}}l7.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$ at 95% C.L. (in units of Bohr magneton), assuming that the solar-neutrino deficit is uniform in neutrino energy.

Hybrid solution of the solar neutrino problem in anticorrelation with sunspot activity.

We describe a mechanism for the new solution of the solar neutrino problem with natural anticorrelation with the solar magnetic-field activity in the convection zone. Our mechanism requires the simultaneous presence of the neutrino flavor mixing and the magnetic (or transition) moment as large as \ensuremath{\mu}B\ensuremath{\sim}${10}^{\mathrm{\ensuremath{-}}10}$ (\ensuremath{\mu} in units of Bohr magneton, B in kG).