Effects of Magnetic Fields on Feeble Magnetic Materials

We introduce magneto-Archimedes separation and the induced magnetic dipole interaction in feeble magnetic materials as a novel method for utilizing high magnetic fields. Under the magneto-Archimedes levitation condition, stable levitation position is materials dependent since it is determined by the differences in volume magnetic susceptibilities and densities between objects and their surroundings. Using this feature, we have successfully demonstrated a novel magnetic separation technique. When powder mixtures composed of feeble magnetic materials were levitated, the initial mixture immediately underwent separation into its component particle aggregates. It was also confirmed that this method is sensitive to both material density and magnetic susceptibility. Interactions among induced magnetic dipoles were observed in the systems of feeble magnetic substances. Usually, such interactions are too small to be observed and have been so far neglected. However, we focused on the interactions and succeeded in observing them by using elaborate experiments. Furthermore, by introducing this interaction to many-particle systems, we obtained some peculiar alignments. These phenomena would be useful to control materials structures, and to bring new applications of magnetic fields into various processes.