Spherical sample holders to improve the susceptibility measurement of superparamagnetic materials

The design of two custom sample holders with a spherical cavity for commercial vibrating sample magnetometer systems is described. For such cavities, the magnetization \documentclass[12pt]{minimal}\begin{document}$\vec{M}$\end{document} M ⃗ and the internal magnetic field \documentclass[12pt]{minimal}\begin{document}$\vec{H_i}$\end{document} H i ⃗ of a sample are both homogeneous. Consequently, the material parameter M ( H i ) of a sample can be determined even for liquids and powders with a high magnetic susceptibility.