Browsing by Author "Forgan, EM"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Exchange-stiffness constant of a Nd-Fe-B based nanocomposite determined by magnetic neutron scattering
    (American Institute of Physics, 2013-09-16) Bick, JP; Suzuki, K; Gilbert, EP; Forgan, EM; Schweins, R; Lindner, P; Kubel, C; Michels, A
    We report magnetic-field-dependent small-angle neutron scattering (SANS) experiments on a Nd2Fe14B/Fe3B nanocomposite. For the two scattering geometries where the applied magnetic field is either perpendicular or parallel to the incoming neutron beam, we have independently analyzed the field-dependent SANS data in terms of micromagnetic theory, taking into account demagnetizing-field effects. The approach in reciprocal space is supported by an analysis of the data in real space and provides consistent results for the exchange-stiffness parameter and the mean magnetic anisotropy-field radius. © 2013, American Institute of Physics.
  • No Thumbnail Available
    Item
    Magnetization reversal in Nd-Fe-B based nanocomposites as seen by magnetic small-angle neutron scattering
    (American Institute of Physics, 2013-01-14) Bick, JP; Honecker, D; Dobrich, F; Suzuki, K; Gilbert, EP; Frielinghaus, H; Kohlbrecher, J; Gavilano, J; Forgan, EM; Schweins, R; Lindner, P; Birringer, R; Michels, A
    We have studied the magnetization-reversal process of a Nd2Fe14B/Fe3B nanocomposite using small-angle neutron scattering. Based on the computation of the autocorrelation function of the spin misalignment, we have estimated the characteristic size l(C) of spin inhomogeneities around the Nd2Fe14B nanoparticles. The quantity l(C) approaches a constant value of about 12.5 nm (similar to average Nd2Fe14B particle radius) at 14 T and takes on a maximum value of about 18.5 nm at the coercive field of -0.55 T. The field dependence of l(C) can be described by a model that takes into account the convolution relationship between the nuclear and the magnetic microstructure. © 2013, American Institute of Physics
  • No Thumbnail Available
    Item
    Polarized neutron Laue diffraction on a crystal containing dynamically polarized proton spins
    (Wiley-Blackwell, 2013-02-01) Piegsa, FM; Karlsson, M; van den Brandt, B; Carlile, CJ; Forgan, EM; Hautle, P; Konter, JA; McIntyre, GJ; Zimmer, O
    A polarized neutron Laue diffraction experiment on a single crystal of neodymium-doped lanthanum magnesium nitrate hydrate containing polarized proton spins is reported. By using dynamic nuclear polarization to polarize the proton spins, it is demonstrated that the intensities of the Bragg peaks can be enhanced or diminished significantly, whilst the incoherent background, due to proton spin disorder, is reduced. It follows that the method offers unique possibilities to tune continuously the contrast of the Bragg reflections and thereby represents a new tool for increasing substantially the signal-to-noise ratio in neutron diffraction patterns of hydrogenous matter.© 2013, Wiley-Blackwell.