Dynamics of field induced ordering processes in ferrofluids studied by polarised small angle neutron scattering

The relaxation of the local ordering of nanoparticles induced by an external magnetic field in a concentrated Cobalt ferrofluid was studied by stroboscopic polarised small angle neutron scattering. Magnetic and nuclear correlations were found to decay exponentially within a characteristic time of few seconds. The local hexagonal particle arrangements with aligned moments transform gradually to uncorrelated segments of dipolar chains. The dynamics is influenced by dipole dipole interaction