Search results for "magnetic dipole moment"
showing 10 items of 117 documents
Large orbital moments and internal magnetic fields in lithium nitridoferrate(I)
2002
The iron nitridometalates Li2[(Li(1-x)Fe(I)(x))N] display ferromagnetic ordering and spin freezing. Large magnetic moments up to 5.0mu(B)/Fe are found in the magnetization. In Mössbauer effect studies huge hyperfine magnetic fields up to 696 kOe are observed at specific Fe sites. These extraordinary fields and moments originate in an unusual ligand field splitting for those Fe species leading [within local spin density approximation (LSDA)] to a localized orbitally degenerate doublet. Including spin-orbit interaction and strong intra-atomic electron correlation (LDA+SO+U) gives rise to a large orbital momentum.
Measurement of the Magnetic Moment of the One-Neutron Halo NucleusB11e
1999
The magnetic moment of ${}^{11}\mathrm{Be}$ ( ${T}_{1/2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}13.8\phantom{\rule{0ex}{0ex}}\mathrm{s}$) was measured by detecting nuclear magnetic resonance signals in a beryllium crystal lattice. The experimental technique applied to a ${}^{11}{\mathrm{Be}}^{+}$ ion beam from a laser ion source includes in-beam optical polarization, implantation into a metallic single crystal, and observation of rf resonances in the asymmetric angular distribution of the $\ensuremath{\beta}$ decay ( $\ensuremath{\beta}$-NMR). The nuclear magnetic moment $\ensuremath{\mu}{(}^{11}\mathrm{Be})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}1.6816(8…
Self-consistency conditions for localized magnetic moments in a free electron gas
1969
The self-consistent conditions for a localized magnetic moment in a metal are studied in the case where the density of states of the host metal is free electron like. A method is outlined which in principle allows to determine self-consistently in the Hartree-Fock approximation the relevant parameters of the magnetic ground state of the system. A numerical example is approximately worked out to show how the theory gives reasonable answers in spite of the crudeness of some of the approximations used.
Search at the Mainz Microtron for light massive gauge bosons relevant for the muon g-2 anomaly.
2014
A massive, but light, Abelian U(1) gauge boson is a well-motivated possible signature of physics beyond the standard model of particle physics. In this Letter, the search for the signal of such a U(1) gauge boson in electron-positron pair production at the spectrometer setup of the A1 Collaboration at the Mainz Microtron is described. Exclusion limits in the mass range of 40 MeV/c^{2} to 300 MeV/c^{2}, with a sensitivity in the squared mixing parameter of as little as ε^{2}=8×10^{-7} are presented. A large fraction of the parameter space has been excluded where the discrepancy of the measured anomalous magnetic moment of the muon with theory might be explained by an additional U(1) gauge …
Overview of the hadronic light-by-light contribution to the muon (g−2)
2014
In this talk I review the recent progress on the numerical evaluation of the Hadronic Light-by-Light contribution to the anomalous magnetic moment of the muon and I discuss the role of experimental data on the accuracy of its determination.
Evolution of Mixed Dirac Particles Interacting with an External Magnetic Field
2007
We study in the framework of relativistic quantum mechanics the evolution of a system of two Dirac neutrinos that mix with each other and have non-vanishing magnetic moments. The dynamics of this system in an external magnetic field is determined by solving the Pauli-Dirac equation with a given initial condition. We consider first neutrino spin-flavor oscillations in a constant magnetic field and derive an analytical expression for the transition probability of spin-flavor conversion in the limit of small magnetic interactions. We then investigate ultrarelativistic neutrinos in an transversal magnetic field and derive their wave functions and transition probabilities with no limitation for …
WMAPing the Universe: Supersymmetry, Dark Matter, Dark Energy, Proton Decay and Collider Physics
2003
In this review we discuss constraints on minimal supersymmetric models of particle physics implied by the recent astrophysical observations of WMAP. Although the prospects of detecting supersymmetry increase and 90 percent of the available MSSM parameter space can safely be reached by the sensitivity of future colliders, nevertheless we pay particular emphasis on discussing regions of the appropriate phase diagrams, which -if realized - would imply that detection of supersymmetry, at least in the context of minimal models, could be out of colliders reach. We also discuss the importance of a precise determination of the radiative corrections to the muon anomalous magnetic moment, both theore…
Correlation in the transition-metal-based Heusler compoundsCo2MnSiandCo2FeSi
2006
Half-metallic ferromagnets, such as the Heusler compounds with formula ${X}_{2}YZ$, are expected to show an integer value for the spin magnetic moment. In contrast to experiments, calculations give noninteger values in certain cases where the compounds are based on $X=\mathrm{Co}$. In order to explain deviations of the magnetic moment calculated for such compounds, the dependence of the electronic structure on the lattice parameter was studied theoretically. In the local density approximation (LDA), the minimum total energy of ${\mathrm{Co}}_{2}\mathrm{FeSi}$ is found for the experimental lattice parameter, but the calculated magnetic moment is approximately 12% too low. In addition, half-m…
Dynamics of topological spin structures
2015
Topological spin structures that emerge from the Dzyaloshinskii-Moriya interaction (DMI), such as chiral domain walls and skyrmions have become the focus of intense investigations due to exciting physics and possible applications [1].
The g-factor of the Electron Bound in Hydrogen-like Ions
1999
The experimental determination of the magnetic moment (g-factor) of the electron bound in hydrogen-like ions represents a clean test of Quantum Electrodynamics, because it is not very sensitive to nuclear structure effects. Experimental data on the g-factor of the bound electron are available only for the hydrogen atom and the 4He+-ion. In this paper we present the first result for the g-factor of hydrogen-like carbon (12C5+). The experimental accuracy is high enough to verify the relativistic contribution to the g-factor on the 10-3 level.