Core-Shell Magnetic Morphology of Structurally Uniform Magnetite Nanoparticles

摘要

A new development in small-angle neutron scattering with polarization analysis allows us to directlynextract the average spatial distributions of magnetic moments and their correlations with three-ndimensional directional sensitivity in any magnetic field. Applied to a collection of spherical magnetitennanoparticles 9.0 nm in diameter, this enhanced method reveals uniformly canted, magnetically activenshells in a nominally saturating field of 1.2 T. The shell thickness depends on temperature, and itndisappears altogether when the external field is removed, confirming that these canted nanoparticle shellsnare magnetic, rather than structural, in origin.