Measuring the exchange-stiffness constant of nanocrystalline solids by elastic small-angle neutron scattering

In ferromagnets with a non-uniform magnetocrystalline and/or magnetoelastic anisotropy, such as nanocrystalline or cold-worked polycrystalline materia ls, the static magnetic microstructure gives rise to elastic magnetic small -angle neutron scattering (SANS). The paper explores a method for determini ng the exchange-stiffness constant A by analysis of the dependence of the e lastic SANS cross-section on the applied magnetic field. Experimental resul ts for A and for the spin-wave stiffness constant D in cold-worked or nanoc rystalline Ni and Co are found to agree with literature data obtained by in elastic neutron scattering on single-crystal specimens.