Small-angle neutron scattering with polarization analysis reveals that Fe3O4 nanoparticles with 90 Å diameters have ferrimagnetic moments significantly reduced from that of bulk Fe3O4 at 10 K, nominal saturation. Combined with previous results for an equivalent applied field at 200 K, a core-disordered shell picture of a spatially reduced ferrimagnetic core emerges, even well below the bulk blocking temperature. Zero-field cooling suggests that this magnetic morphology may be intrinsic to the nanoparticle, rather than field induced, at 10 K.
Krycka, K.L., J.A. Borchers, R.A. Booth, et al. 2010. "Internal magnetic structure of magnetite nanoparticles at low temperature." Journal of Applied Physics 107: 09B525.
Journal of Applied Physics
Physics and Astronomy
Magnetic nanoparticles, Polarized neutron scattering