Klokkenburg, M. ; Erné, B.H. ; Wiedenmann, A. ; Petukhov, A.V. ; Philipse, A.P.: Dipolar structures in magnetite ferrofluids studied with small-angle neutron scattering with and without applied magnetic field. Physical Review E 75 (2007), p. 051408/1-9
Abstract:
Field-induced structure formation in a ferrofluid with well-defined magnetite nanoparticles with a permanent magnetic dipole moment was studied with small-angle neutron scattering SANS as a function of the magnetic interactions. The interactions were tuned by adjusting the size of the well-defined, single-magnetic-domain magnetite Fe3O4 particles and by applying an external magnetic field. For decreasing particle dipole moments, the data show a progressive distortion of the hexagonal symmetry, resulting from the formation of magnetic sheets. The SANS data show qualitative agreement with recent cryogenic transmission electron microscopy results obtained in 2D Klokkenburg et al., Phys. Rev. Lett. 97, 185702 2006 on the same ferrofluids.