  We investigate the spatial distribution of spin orientation in magnetic
nanoparticles consisting of hard and soft magnetic layers. The nanoparticles
are synthesized in a core / shell spherical morphology where the magnetically
hard, high anisotropy layer is CoFe$_2$O$_4$ (CFO) while the lower anisotropy
material is Fe$_3$O$_4$ (FO). The nanoparticles have a mean diameter of
$\sim$9.2 - 9.6 nm and are synthesized as two variants: a conventional hard /
soft core / shell structure with a CFO core / FO shell (CFO@FO) and the
inverted structure FO core / CFO shell (FO@CFO). High resolution electron
microscopy confirms the coherent spinel structure across the core / shell
boundary in both variants while magnetometry indicates the nanoparticles are
superparamagnetic at 300 K and develop a considerable anisotropy at reduced
temperatures. Low temperature \textit{M vs. H} loops suggest a multi-step
reversal process. Temperature dependent small angle neutron scattering (SANS)
with full polarization analysis reveals a strong perpendicular plane alignment
of the spins near zero field, indicative of spin canting, but the perpendicular
alignment quickly disappears upon application of a weak field and little spin
ordering parallel to the field until the coercive field is reached. Above the
coercive field of the sample, spins orient predominantly along the field
direction. At both zero field and near saturation, the parallel magnetic SANS
peak coincides with the structural peak, indicating the magnetization is
uniform throughout the nanoparticle volume, while near the coercive field the
parallel scattering peak shifts to higher momentum transfer (Q), suggesting
that the coherent scattering volume is smaller and likely originates in the
softer Fe$_3$O$_4$ portion of the nanoparticle.
