Reference : Exchange-stiffness constant in cold-worked and nanocrystalline Ni measured by elastic...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Physics
http://hdl.handle.net/10993/592
Exchange-stiffness constant in cold-worked and nanocrystalline Ni measured by elastic small-angle neutron scattering
English
Michels, Andreas mailto [Universität des Saarlandes, Saarbrücken, Germany]
Weissmüller, J. [Institut für Nanotechnologie, Forschungszentrum Karlsruhe, Karlsruhe, Germany]
Wiedenmann, A. [Hahn-Meitner-Institut, D-14109 Berlin, Germany]
Barker, J. G. [National Institute of Standards and Technology, Gaithersburg, Maryland, USA]
2000
Journal of Applied Physics
American Institute of Physics
87
9
5953 - 5955
Yes (verified by ORBilu)
0021-8979
Melville
NY
[en] neutron diffraction ; ferromagnetic materials ; nanostructured materials ; magnetisation ; cold working ; magnetic domains ; electrodeposits ; magnetic thin films ; magnetic anisotropy ; exchange interactions (electron) ; nickel
[en] We present a new method for determining the exchange-stiffness constant A of a ferromagnetic bulk material by field-dependent elastic small-angle neutron scattering (SANS). In the limit of high applied magnetic field H, for which the scattering volume is a single magnetic domain and the magnetization is nearly aligned with the direction of the applied field, a combination of micromagnetics theory with neutron scattering formalism suggests closed-form expressions for the differential scattering cross section as a function of the scattering vector and of H. Based on these results it is suggested that the exchange-stiffness constant can be extracted from experimental SANS data recorded as a function of H. At ambient temperature we have applied this method to polycrystalline cold-worked Ni and nanocrystalline electrodeposited Ni, finding exchange-stiffness constants of (8.2±0.2)×10−12 and (7.6±0.3)×10−12  J/m, respectively. Measurement at 5 K yields a value of (9.2±0.2)×10−12 J/m for the nanocrystalline sample, a temperature dependence that agrees qualitatively with data in the literature. In addition to the value of A, the technique supplies information on the spatial structure of the magnetic anisotropy field.
http://hdl.handle.net/10993/592
10.1063/1.372577

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