Visualization and quantification of four steps in magnetic field induced two-dimensional ordering of superparamagnetic submicron particles

We hereby report a methodology that permits a quantitative investigation of the temporal self-organization of submicron sized superparamagnetic composite particles in the presence of an external magnetic field. The kinetics of field-induced self-organization into linear chains, time-dependent chain-size distribution, resolved growth steps (condensation, polarization, colinearity, and concatenation), the average chain growth rate, and interparticle interaction length were calculated in the presence of a 120 G external magnetic field using optical microscopy and "in-house" developed image analysis software. The measurements are in good agreement with theoretical assumptions. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3475770]