Static magnetometer suitable for weakly permeable magnetic fluids. Highlighting method of anisotropy assessment

Ferrofluids have a highly nonlinear magnetic behavior. Moreover, their colloidal nature may, in certain circumstances, make anisotropic by forming chains. A fine characterization of these liquids is essential. However, conventional measurement methods, setting in motion the samples tested are ineffective against these materials. The following article highlights a static method to draw the characteristic J(H) of a sample of ferrofluid. It consists in four parts. The first describes the measurement principle and the mathematical method involved. The second part of the article shows how the magnetometer was designed, implemented and calibrated. In the third part, the magnetometer is tested on a solid sample slightly permeable. Down results obtained are compared to measurement by extraction. Finally, a fourth part shows thanks to a numerical simulation that the device is able to highlight the isotropic or anisotropic nature of the test sample.