Self-organization of nonmagnetic spheres by magnetic field

Two-dimensional crystallization of nonmagnetic gold spheres was achieved by the application of a high magnetic field. This phenomenon is based on the two different forces caused by a magnetic field; interactions between magnetic dipoles induced in the nonmagnetic spheres and magnetic force derived from field gradient. The former force is generally so weak and, hence, negligible. However, under an appropriate condition, we can achieve the subtle balance between the two forces. This phenomenon is a new class of self-assembling phenomena, and we believe that our achievement will be a milestone in the utilization of magnetic fields.