FIELD-DEPENDENT CHAIN FORMATION BY FERROMAGNETIC COLLOIDS

Field dependent chain formation in ferromagnetic colloids is discussed. It is shown that chains form if the density of ferromagnetic particles is sufficiently low and if the dipole-dipole coupling is sufficiently strong. In small magnetic fields the chains may only be metastable; they are stable in high fields. General formulae for calculating the mean chain length as a function of density, dipole-dipole coupling constant and dipole-field coupling constant are given and compared with available experimental data. © 1979 Taylor & Francis Ltd.