Measuring Magnetization Curves of Ferrofluids: Comparison of the Differential Sweep Method and a Vibrating-Sample Magnetometer

A setup design is proposed for measuring magnetization curves by the differential sweep method. On the described setup, a number of magnetization curves were measured for both classical magnetic fluids and samples obtained by their solidification. The measurement results are compared with the results obtained using a vibrating-sample magnetometer. It is shown that the vibrating-sample magnetometer gives significantly lower values compared to the differential method when measuring the magnetization of a magnetic fluid. When measuring the magnetization of a cured magnetic-fluid sample, a complete coincidence of the results obtained by both measurement methods is observed. The discovered phenomenon is explained by the aggregation of particles in the magnetic fluid under the influence of a magnetic field. Estimations of the relative delay in the movement of aggregates are consistent with the observed divergence in the magnetization magnitude.