  Magnetic-field-dependent unpolarized small-angle neutron scattering (SANS)
experiments demonstrate that high-pressure torsion (HPT) straining induces spin
misalignments in pure Ni, which persist in magnetic fields up to 4 T. The
spin-misalignment scattering patterns are elongated perpendicular to the
applied magnetic field due to an unusual predominant longitudinal
$sin^2(\theta)$-type angular anisotropy. Such a contribution cannot be
explained by the conventional second order (in spin misalignment amplitude)
micromagnetic SANS theory in the approach-to-saturation regime, nor can its
magnitude relative to the other features of the cross sections by the third
order micromagnetic SANS theory. This indicates that the high-density of
crystal defects induced via HPT straining in Ni makes such higher-order effects
in the micromagnetic SANS cross sections observable.
